diff --git a/include/MqttSettings.h b/include/MqttSettings.h
index 6a22af4..2434253 100644
--- a/include/MqttSettings.h
+++ b/include/MqttSettings.h
@@ -19,7 +19,7 @@ public:
     void subscribe(const String& topic, const uint8_t qos, const espMqttClientTypes::OnMessageCallback& cb);
     void unsubscribe(const String& topic);
 
-    String getPrefix();
+    String getPrefix() const;
 
 private:
     void NetworkEvent(network_event event);
diff --git a/include/NetworkSettings.h b/include/NetworkSettings.h
index 3fd26e5..8d4de18 100644
--- a/include/NetworkSettings.h
+++ b/include/NetworkSettings.h
@@ -42,16 +42,16 @@ public:
     void init(Scheduler* scheduler);
     void applyConfig();
     void enableAdminMode();
-    String getApName();
+    String getApName() const;
 
-    IPAddress localIP();
-    IPAddress subnetMask();
-    IPAddress gatewayIP();
-    IPAddress dnsIP(const uint8_t dns_no = 0);
-    String macAddress();
+    IPAddress localIP() const;
+    IPAddress subnetMask() const;
+    IPAddress gatewayIP() const;
+    IPAddress dnsIP(const uint8_t dns_no = 0) const;
+    String macAddress() const;
     static String getHostname();
-    bool isConnected();
-    network_mode NetworkMode();
+    bool isConnected() const;
+    network_mode NetworkMode() const;
 
     bool onEvent(NetworkEventCb cbEvent, const network_event event = network_event::NETWORK_EVENT_MAX);
     void raiseEvent(const network_event event);
diff --git a/include/PinMapping.h b/include/PinMapping.h
index 2360a67..e0db88b 100644
--- a/include/PinMapping.h
+++ b/include/PinMapping.h
@@ -47,9 +47,9 @@ public:
     bool init(const String& deviceMapping);
     PinMapping_t& get();
 
-    bool isValidNrf24Config();
-    bool isValidCmt2300Config();
-    bool isValidEthConfig();
+    bool isValidNrf24Config() const;
+    bool isValidCmt2300Config() const;
+    bool isValidEthConfig() const;
 
 private:
     PinMapping_t _pinMapping;
diff --git a/include/SunPosition.h b/include/SunPosition.h
index 67a1970..42f818e 100644
--- a/include/SunPosition.h
+++ b/include/SunPosition.h
@@ -10,17 +10,17 @@ public:
     SunPositionClass();
     void init(Scheduler* scheduler);
 
-    bool isDayPeriod();
-    bool isSunsetAvailable();
-    bool sunsetTime(struct tm* info);
-    bool sunriseTime(struct tm* info);
+    bool isDayPeriod() const;
+    bool isSunsetAvailable() const;
+    bool sunsetTime(struct tm* info) const;
+    bool sunriseTime(struct tm* info) const;
     void setDoRecalc(const bool doRecalc);
 
 private:
     void loop();
     void updateSunData();
-    bool checkRecalcDayChanged();
-    bool getSunTime(struct tm* info, const uint32_t offset);
+    bool checkRecalcDayChanged() const;
+    bool getSunTime(struct tm* info, const uint32_t offset) const;
 
     Task _loopTask;
 
diff --git a/lib/Hoymiles/src/Hoymiles.cpp b/lib/Hoymiles/src/Hoymiles.cpp
index bffa808..186910d 100644
--- a/lib/Hoymiles/src/Hoymiles.cpp
+++ b/lib/Hoymiles/src/Hoymiles.cpp
@@ -232,7 +232,7 @@ void HoymilesClass::removeInverterBySerial(const uint64_t serial)
     }
 }
 
-size_t HoymilesClass::getNumInverters()
+size_t HoymilesClass::getNumInverters() const
 {
     return _inverters.size();
 }
@@ -247,12 +247,12 @@ HoymilesRadio_CMT* HoymilesClass::getRadioCmt()
     return _radioCmt.get();
 }
 
-bool HoymilesClass::isAllRadioIdle()
+bool HoymilesClass::isAllRadioIdle() const
 {
     return _radioNrf.get()->isIdle() && _radioCmt.get()->isIdle();
 }
 
-uint32_t HoymilesClass::PollInterval()
+uint32_t HoymilesClass::PollInterval() const
 {
     return _pollInterval;
 }
diff --git a/lib/Hoymiles/src/Hoymiles.h b/lib/Hoymiles/src/Hoymiles.h
index fd467af..733817f 100644
--- a/lib/Hoymiles/src/Hoymiles.h
+++ b/lib/Hoymiles/src/Hoymiles.h
@@ -28,15 +28,15 @@ public:
     std::shared_ptr<InverterAbstract> getInverterBySerial(const uint64_t serial);
     std::shared_ptr<InverterAbstract> getInverterByFragment(const fragment_t* fragment);
     void removeInverterBySerial(const uint64_t serial);
-    size_t getNumInverters();
+    size_t getNumInverters() const;
 
     HoymilesRadio_NRF* getRadioNrf();
     HoymilesRadio_CMT* getRadioCmt();
 
-    uint32_t PollInterval();
+    uint32_t PollInterval() const;
     void setPollInterval(const uint32_t interval);
 
-    bool isAllRadioIdle();
+    bool isAllRadioIdle() const;
 
 private:
     std::vector<std::shared_ptr<InverterAbstract>> _inverters;
diff --git a/lib/Hoymiles/src/HoymilesRadio.cpp b/lib/Hoymiles/src/HoymilesRadio.cpp
index 086d0ef..8e49f98 100644
--- a/lib/Hoymiles/src/HoymilesRadio.cpp
+++ b/lib/Hoymiles/src/HoymilesRadio.cpp
@@ -6,7 +6,7 @@
 #include "Hoymiles.h"
 #include "crc.h"
 
-serial_u HoymilesRadio::DtuSerial()
+serial_u HoymilesRadio::DtuSerial() const
 {
     return _dtuSerial;
 }
@@ -28,7 +28,7 @@ serial_u HoymilesRadio::convertSerialToRadioId(const serial_u serial)
     return radioId;
 }
 
-bool HoymilesRadio::checkFragmentCrc(const fragment_t* fragment)
+bool HoymilesRadio::checkFragmentCrc(const fragment_t* fragment) const
 {
     const uint8_t crc = crc8(fragment->fragment, fragment->len - 1);
     return (crc == fragment->fragment[fragment->len - 1]);
@@ -124,17 +124,17 @@ void HoymilesRadio::dumpBuf(const uint8_t buf[], const uint8_t len, const bool a
     }
 }
 
-bool HoymilesRadio::isInitialized()
+bool HoymilesRadio::isInitialized() const
 {
     return _isInitialized;
 }
 
-bool HoymilesRadio::isIdle()
+bool HoymilesRadio::isIdle() const
 {
     return !_busyFlag;
 }
 
-bool HoymilesRadio::isQueueEmpty()
+bool HoymilesRadio::isQueueEmpty() const
 {
     return _commandQueue.size() == 0;
 }
diff --git a/lib/Hoymiles/src/HoymilesRadio.h b/lib/Hoymiles/src/HoymilesRadio.h
index 980a203..08ac08f 100644
--- a/lib/Hoymiles/src/HoymilesRadio.h
+++ b/lib/Hoymiles/src/HoymilesRadio.h
@@ -9,12 +9,12 @@
 
 class HoymilesRadio {
 public:
-    serial_u DtuSerial();
+    serial_u DtuSerial() const;
     virtual void setDtuSerial(const uint64_t serial);
 
-    bool isIdle();
-    bool isQueueEmpty();
-    bool isInitialized();
+    bool isIdle() const;
+    bool isQueueEmpty() const;
+    bool isInitialized() const;
 
     void enqueCommand(std::shared_ptr<CommandAbstract> cmd)
     {
@@ -31,7 +31,7 @@ protected:
     static serial_u convertSerialToRadioId(const serial_u serial);
     static void dumpBuf(const uint8_t buf[], const uint8_t len, const bool appendNewline = true);
 
-    bool checkFragmentCrc(const fragment_t* fragment);
+    bool checkFragmentCrc(const fragment_t* fragment) const;
     virtual void sendEsbPacket(CommandAbstract* cmd) = 0;
     void sendRetransmitPacket(const uint8_t fragment_id);
     void sendLastPacketAgain();
diff --git a/lib/Hoymiles/src/HoymilesRadio_CMT.cpp b/lib/Hoymiles/src/HoymilesRadio_CMT.cpp
index 062bc12..b3d7dd4 100644
--- a/lib/Hoymiles/src/HoymilesRadio_CMT.cpp
+++ b/lib/Hoymiles/src/HoymilesRadio_CMT.cpp
@@ -178,12 +178,12 @@ void HoymilesRadio_CMT::setInverterTargetFrequency(const uint32_t frequency)
     cmtSwitchDtuFreq(_inverterTargetFrequency);
 }
 
-uint32_t HoymilesRadio_CMT::getInverterTargetFrequency()
+uint32_t HoymilesRadio_CMT::getInverterTargetFrequency() const
 {
     return _inverterTargetFrequency;
 }
 
-bool HoymilesRadio_CMT::isConnected()
+bool HoymilesRadio_CMT::isConnected() const
 {
     if (!_isInitialized) {
         return false;
diff --git a/lib/Hoymiles/src/HoymilesRadio_CMT.h b/lib/Hoymiles/src/HoymilesRadio_CMT.h
index 78af3ac..8a4bb1f 100644
--- a/lib/Hoymiles/src/HoymilesRadio_CMT.h
+++ b/lib/Hoymiles/src/HoymilesRadio_CMT.h
@@ -22,9 +22,9 @@ public:
     void loop();
     void setPALevel(const int8_t paLevel);
     void setInverterTargetFrequency(const uint32_t frequency);
-    uint32_t getInverterTargetFrequency();
+    uint32_t getInverterTargetFrequency() const;
 
-    bool isConnected();
+    bool isConnected() const;
 
     static uint32_t getMinFrequency();
     static uint32_t getMaxFrequency();
diff --git a/lib/Hoymiles/src/HoymilesRadio_NRF.cpp b/lib/Hoymiles/src/HoymilesRadio_NRF.cpp
index a69d31c..9cb2cc5 100644
--- a/lib/Hoymiles/src/HoymilesRadio_NRF.cpp
+++ b/lib/Hoymiles/src/HoymilesRadio_NRF.cpp
@@ -115,7 +115,7 @@ void HoymilesRadio_NRF::setDtuSerial(const uint64_t serial)
     openReadingPipe();
 }
 
-bool HoymilesRadio_NRF::isConnected()
+bool HoymilesRadio_NRF::isConnected() const
 {
     if (!_isInitialized) {
         return false;
@@ -123,7 +123,7 @@ bool HoymilesRadio_NRF::isConnected()
     return _radio->isChipConnected();
 }
 
-bool HoymilesRadio_NRF::isPVariant()
+bool HoymilesRadio_NRF::isPVariant() const
 {
     if (!_isInitialized) {
         return false;
diff --git a/lib/Hoymiles/src/HoymilesRadio_NRF.h b/lib/Hoymiles/src/HoymilesRadio_NRF.h
index 22798b8..a23c1e0 100644
--- a/lib/Hoymiles/src/HoymilesRadio_NRF.h
+++ b/lib/Hoymiles/src/HoymilesRadio_NRF.h
@@ -19,8 +19,8 @@ public:
 
     virtual void setDtuSerial(const uint64_t serial);
 
-    bool isConnected();
-    bool isPVariant();
+    bool isConnected() const;
+    bool isPVariant() const;
 
 private:
     void ARDUINO_ISR_ATTR handleIntr();
diff --git a/lib/Hoymiles/src/commands/ActivePowerControlCommand.cpp b/lib/Hoymiles/src/commands/ActivePowerControlCommand.cpp
index 09c2df7..8e34d91 100644
--- a/lib/Hoymiles/src/commands/ActivePowerControlCommand.cpp
+++ b/lib/Hoymiles/src/commands/ActivePowerControlCommand.cpp
@@ -42,7 +42,7 @@ ActivePowerControlCommand::ActivePowerControlCommand(const uint64_t target_addre
     setTimeout(2000);
 }
 
-String ActivePowerControlCommand::getCommandName()
+String ActivePowerControlCommand::getCommandName() const
 {
     return "ActivePowerControl";
 }
@@ -83,7 +83,7 @@ bool ActivePowerControlCommand::handleResponse(InverterAbstract* inverter, const
     return true;
 }
 
-float ActivePowerControlCommand::getLimit()
+float ActivePowerControlCommand::getLimit() const
 {
     const uint16_t l = (((uint16_t)_payload[12] << 8) | _payload[13]);
     return l / 10;
diff --git a/lib/Hoymiles/src/commands/ActivePowerControlCommand.h b/lib/Hoymiles/src/commands/ActivePowerControlCommand.h
index 2318348..b509a09 100644
--- a/lib/Hoymiles/src/commands/ActivePowerControlCommand.h
+++ b/lib/Hoymiles/src/commands/ActivePowerControlCommand.h
@@ -14,12 +14,12 @@ class ActivePowerControlCommand : public DevControlCommand {
 public:
     explicit ActivePowerControlCommand(const uint64_t target_address = 0, const uint64_t router_address = 0);
 
-    virtual String getCommandName();
+    virtual String getCommandName() const;
 
     virtual bool handleResponse(InverterAbstract* inverter, const fragment_t fragment[], const uint8_t max_fragment_id);
     virtual void gotTimeout(InverterAbstract* inverter);
 
     void setActivePowerLimit(const float limit, const PowerLimitControlType type = RelativNonPersistent);
-    float getLimit();
+    float getLimit() const;
     PowerLimitControlType getType();
 };
\ No newline at end of file
diff --git a/lib/Hoymiles/src/commands/AlarmDataCommand.cpp b/lib/Hoymiles/src/commands/AlarmDataCommand.cpp
index 1192a16..8416b1e 100644
--- a/lib/Hoymiles/src/commands/AlarmDataCommand.cpp
+++ b/lib/Hoymiles/src/commands/AlarmDataCommand.cpp
@@ -31,7 +31,7 @@ AlarmDataCommand::AlarmDataCommand(const uint64_t target_address, const uint64_t
     setTimeout(750);
 }
 
-String AlarmDataCommand::getCommandName()
+String AlarmDataCommand::getCommandName() const
 {
     return "AlarmData";
 }
diff --git a/lib/Hoymiles/src/commands/AlarmDataCommand.h b/lib/Hoymiles/src/commands/AlarmDataCommand.h
index d9f2931..1b61d5c 100644
--- a/lib/Hoymiles/src/commands/AlarmDataCommand.h
+++ b/lib/Hoymiles/src/commands/AlarmDataCommand.h
@@ -7,7 +7,7 @@ class AlarmDataCommand : public MultiDataCommand {
 public:
     explicit AlarmDataCommand(const uint64_t target_address = 0, const uint64_t router_address = 0, const time_t time = 0);
 
-    virtual String getCommandName();
+    virtual String getCommandName() const;
 
     virtual bool handleResponse(InverterAbstract* inverter, const fragment_t fragment[], const uint8_t max_fragment_id);
     virtual void gotTimeout(InverterAbstract* inverter);
diff --git a/lib/Hoymiles/src/commands/ChannelChangeCommand.cpp b/lib/Hoymiles/src/commands/ChannelChangeCommand.cpp
index 636c952..da111ab 100644
--- a/lib/Hoymiles/src/commands/ChannelChangeCommand.cpp
+++ b/lib/Hoymiles/src/commands/ChannelChangeCommand.cpp
@@ -32,7 +32,7 @@ ChannelChangeCommand::ChannelChangeCommand(const uint64_t target_address, const
     setTimeout(10);
 }
 
-String ChannelChangeCommand::getCommandName()
+String ChannelChangeCommand::getCommandName() const
 {
     return "ChannelChangeCommand";
 }
@@ -42,7 +42,7 @@ void ChannelChangeCommand::setChannel(const uint8_t channel)
     _payload[12] = channel;
 }
 
-uint8_t ChannelChangeCommand::getChannel()
+uint8_t ChannelChangeCommand::getChannel() const
 {
     return _payload[12];
 }
diff --git a/lib/Hoymiles/src/commands/ChannelChangeCommand.h b/lib/Hoymiles/src/commands/ChannelChangeCommand.h
index f114f0e..be598b9 100644
--- a/lib/Hoymiles/src/commands/ChannelChangeCommand.h
+++ b/lib/Hoymiles/src/commands/ChannelChangeCommand.h
@@ -7,10 +7,10 @@ class ChannelChangeCommand : public CommandAbstract {
 public:
     explicit ChannelChangeCommand(const uint64_t target_address = 0, const uint64_t router_address = 0, const uint8_t channel = 0);
 
-    virtual String getCommandName();
+    virtual String getCommandName() const;
 
     void setChannel(const uint8_t channel);
-    uint8_t getChannel();
+    uint8_t getChannel() const;
 
     virtual bool handleResponse(InverterAbstract* inverter, const fragment_t fragment[], const uint8_t max_fragment_id);
 
diff --git a/lib/Hoymiles/src/commands/CommandAbstract.cpp b/lib/Hoymiles/src/commands/CommandAbstract.cpp
index 2395032..5f612b4 100644
--- a/lib/Hoymiles/src/commands/CommandAbstract.cpp
+++ b/lib/Hoymiles/src/commands/CommandAbstract.cpp
@@ -56,7 +56,7 @@ void CommandAbstract::dumpDataPayload(Print* stream)
     stream->println("");
 }
 
-uint8_t CommandAbstract::getDataSize()
+uint8_t CommandAbstract::getDataSize() const
 {
     return _payload_size + 1; // Original payload plus crc8
 }
@@ -66,7 +66,7 @@ void CommandAbstract::setTargetAddress(const uint64_t address)
     convertSerialToPacketId(&_payload[1], address);
     _targetAddress = address;
 }
-uint64_t CommandAbstract::getTargetAddress()
+uint64_t CommandAbstract::getTargetAddress() const
 {
     return _targetAddress;
 }
@@ -77,7 +77,7 @@ void CommandAbstract::setRouterAddress(const uint64_t address)
     _routerAddress = address;
 }
 
-uint64_t CommandAbstract::getRouterAddress()
+uint64_t CommandAbstract::getRouterAddress() const
 {
     return _routerAddress;
 }
@@ -87,7 +87,7 @@ void CommandAbstract::setTimeout(const uint32_t timeout)
     _timeout = timeout;
 }
 
-uint32_t CommandAbstract::getTimeout()
+uint32_t CommandAbstract::getTimeout() const
 {
     return _timeout;
 }
@@ -97,7 +97,7 @@ void CommandAbstract::setSendCount(const uint8_t count)
     _sendCount = count;
 }
 
-uint8_t CommandAbstract::getSendCount()
+uint8_t CommandAbstract::getSendCount() const
 {
     return _sendCount;
 }
@@ -126,12 +126,12 @@ void CommandAbstract::gotTimeout(InverterAbstract* inverter)
 {
 }
 
-uint8_t CommandAbstract::getMaxResendCount()
+uint8_t CommandAbstract::getMaxResendCount() const
 {
     return MAX_RESEND_COUNT;
 }
 
-uint8_t CommandAbstract::getMaxRetransmitCount()
+uint8_t CommandAbstract::getMaxRetransmitCount() const
 {
     return MAX_RETRANSMIT_COUNT;
 }
diff --git a/lib/Hoymiles/src/commands/CommandAbstract.h b/lib/Hoymiles/src/commands/CommandAbstract.h
index 9ce0d6b..fd90130 100644
--- a/lib/Hoymiles/src/commands/CommandAbstract.h
+++ b/lib/Hoymiles/src/commands/CommandAbstract.h
@@ -19,21 +19,21 @@ public:
     const uint8_t* getDataPayload();
     void dumpDataPayload(Print* stream);
 
-    uint8_t getDataSize();
+    uint8_t getDataSize() const;
 
     void setTargetAddress(const uint64_t address);
-    uint64_t getTargetAddress();
+    uint64_t getTargetAddress() const;
 
     void setRouterAddress(const uint64_t address);
-    uint64_t getRouterAddress();
+    uint64_t getRouterAddress() const;
 
     void setTimeout(const uint32_t timeout);
-    uint32_t getTimeout();
+    uint32_t getTimeout() const;
 
-    virtual String getCommandName() = 0;
+    virtual String getCommandName() const = 0;
 
     void setSendCount(const uint8_t count);
-    uint8_t getSendCount();
+    uint8_t getSendCount() const;
     uint8_t incrementSendCount();
 
     virtual CommandAbstract* getRequestFrameCommand(const uint8_t frame_no);
@@ -42,10 +42,10 @@ public:
     virtual void gotTimeout(InverterAbstract* inverter);
 
     // Sets the amount how often the specific command is resent if all fragments where missing
-    virtual uint8_t getMaxResendCount();
+    virtual uint8_t getMaxResendCount() const;
 
     // Sets the amount how often a missing fragment is re-requested if it was not available
-    virtual uint8_t getMaxRetransmitCount();
+    virtual uint8_t getMaxRetransmitCount() const;
 
 protected:
     uint8_t _payload[RF_LEN];
diff --git a/lib/Hoymiles/src/commands/DevInfoAllCommand.cpp b/lib/Hoymiles/src/commands/DevInfoAllCommand.cpp
index cab65ab..be16dbb 100644
--- a/lib/Hoymiles/src/commands/DevInfoAllCommand.cpp
+++ b/lib/Hoymiles/src/commands/DevInfoAllCommand.cpp
@@ -29,7 +29,7 @@ DevInfoAllCommand::DevInfoAllCommand(const uint64_t target_address, const uint64
     setTimeout(200);
 }
 
-String DevInfoAllCommand::getCommandName()
+String DevInfoAllCommand::getCommandName() const
 {
     return "DevInfoAll";
 }
diff --git a/lib/Hoymiles/src/commands/DevInfoAllCommand.h b/lib/Hoymiles/src/commands/DevInfoAllCommand.h
index 5878e2f..7ad4e18 100644
--- a/lib/Hoymiles/src/commands/DevInfoAllCommand.h
+++ b/lib/Hoymiles/src/commands/DevInfoAllCommand.h
@@ -7,7 +7,7 @@ class DevInfoAllCommand : public MultiDataCommand {
 public:
     explicit DevInfoAllCommand(const uint64_t target_address = 0, const uint64_t router_address = 0, const time_t time = 0);
 
-    virtual String getCommandName();
+    virtual String getCommandName() const;
 
     virtual bool handleResponse(InverterAbstract* inverter, const fragment_t fragment[], const uint8_t max_fragment_id);
 };
\ No newline at end of file
diff --git a/lib/Hoymiles/src/commands/DevInfoSimpleCommand.cpp b/lib/Hoymiles/src/commands/DevInfoSimpleCommand.cpp
index 8703df0..7fccf19 100644
--- a/lib/Hoymiles/src/commands/DevInfoSimpleCommand.cpp
+++ b/lib/Hoymiles/src/commands/DevInfoSimpleCommand.cpp
@@ -29,7 +29,7 @@ DevInfoSimpleCommand::DevInfoSimpleCommand(const uint64_t target_address, const
     setTimeout(200);
 }
 
-String DevInfoSimpleCommand::getCommandName()
+String DevInfoSimpleCommand::getCommandName() const
 {
     return "DevInfoSimple";
 }
diff --git a/lib/Hoymiles/src/commands/DevInfoSimpleCommand.h b/lib/Hoymiles/src/commands/DevInfoSimpleCommand.h
index 6bedec5..56a20c9 100644
--- a/lib/Hoymiles/src/commands/DevInfoSimpleCommand.h
+++ b/lib/Hoymiles/src/commands/DevInfoSimpleCommand.h
@@ -7,7 +7,7 @@ class DevInfoSimpleCommand : public MultiDataCommand {
 public:
     explicit DevInfoSimpleCommand(const uint64_t target_address = 0, const uint64_t router_address = 0, const time_t time = 0);
 
-    virtual String getCommandName();
+    virtual String getCommandName() const;
 
     virtual bool handleResponse(InverterAbstract* inverter, const fragment_t fragment[], const uint8_t max_fragment_id);
 };
\ No newline at end of file
diff --git a/lib/Hoymiles/src/commands/GridOnProFilePara.cpp b/lib/Hoymiles/src/commands/GridOnProFilePara.cpp
index 6e1a97b..5b7b0ff 100644
--- a/lib/Hoymiles/src/commands/GridOnProFilePara.cpp
+++ b/lib/Hoymiles/src/commands/GridOnProFilePara.cpp
@@ -30,7 +30,7 @@ GridOnProFilePara::GridOnProFilePara(const uint64_t target_address, const uint64
     setTimeout(500);
 }
 
-String GridOnProFilePara::getCommandName()
+String GridOnProFilePara::getCommandName() const
 {
     return "GridOnProFilePara";
 }
diff --git a/lib/Hoymiles/src/commands/GridOnProFilePara.h b/lib/Hoymiles/src/commands/GridOnProFilePara.h
index b2927c0..ff1c457 100644
--- a/lib/Hoymiles/src/commands/GridOnProFilePara.h
+++ b/lib/Hoymiles/src/commands/GridOnProFilePara.h
@@ -7,7 +7,7 @@ class GridOnProFilePara : public MultiDataCommand {
 public:
     explicit GridOnProFilePara(const uint64_t target_address = 0, const uint64_t router_address = 0, const time_t time = 0);
 
-    virtual String getCommandName();
+    virtual String getCommandName() const;
 
     virtual bool handleResponse(InverterAbstract* inverter, const fragment_t fragment[], const uint8_t max_fragment_id);
 };
\ No newline at end of file
diff --git a/lib/Hoymiles/src/commands/MultiDataCommand.cpp b/lib/Hoymiles/src/commands/MultiDataCommand.cpp
index e752660..af714ea 100644
--- a/lib/Hoymiles/src/commands/MultiDataCommand.cpp
+++ b/lib/Hoymiles/src/commands/MultiDataCommand.cpp
@@ -55,7 +55,7 @@ void MultiDataCommand::setDataType(const uint8_t data_type)
     _payload[10] = data_type;
     udpateCRC();
 }
-uint8_t MultiDataCommand::getDataType()
+uint8_t MultiDataCommand::getDataType() const
 {
     return _payload[10];
 }
@@ -69,7 +69,7 @@ void MultiDataCommand::setTime(const time_t time)
     udpateCRC();
 }
 
-time_t MultiDataCommand::getTime()
+time_t MultiDataCommand::getTime() const
 {
     return (time_t)(_payload[12] << 24)
         | (time_t)(_payload[13] << 16)
diff --git a/lib/Hoymiles/src/commands/MultiDataCommand.h b/lib/Hoymiles/src/commands/MultiDataCommand.h
index 6698fec..2a01a30 100644
--- a/lib/Hoymiles/src/commands/MultiDataCommand.h
+++ b/lib/Hoymiles/src/commands/MultiDataCommand.h
@@ -10,7 +10,7 @@ public:
     explicit MultiDataCommand(const uint64_t target_address = 0, const uint64_t router_address = 0, const uint8_t data_type = 0, const time_t time = 0);
 
     void setTime(const time_t time);
-    time_t getTime();
+    time_t getTime() const;
 
     CommandAbstract* getRequestFrameCommand(const uint8_t frame_no);
 
@@ -18,7 +18,7 @@ public:
 
 protected:
     void setDataType(const uint8_t data_type);
-    uint8_t getDataType();
+    uint8_t getDataType() const;
     void udpateCRC();
     static uint8_t getTotalFragmentSize(const fragment_t fragment[], const uint8_t max_fragment_id);
 
diff --git a/lib/Hoymiles/src/commands/PowerControlCommand.cpp b/lib/Hoymiles/src/commands/PowerControlCommand.cpp
index 6940c24..749b340 100644
--- a/lib/Hoymiles/src/commands/PowerControlCommand.cpp
+++ b/lib/Hoymiles/src/commands/PowerControlCommand.cpp
@@ -39,7 +39,7 @@ PowerControlCommand::PowerControlCommand(const uint64_t target_address, const ui
     setTimeout(2000);
 }
 
-String PowerControlCommand::getCommandName()
+String PowerControlCommand::getCommandName() const
 {
     return "PowerControl";
 }
diff --git a/lib/Hoymiles/src/commands/PowerControlCommand.h b/lib/Hoymiles/src/commands/PowerControlCommand.h
index dd2ae8d..1f13c06 100644
--- a/lib/Hoymiles/src/commands/PowerControlCommand.h
+++ b/lib/Hoymiles/src/commands/PowerControlCommand.h
@@ -7,7 +7,7 @@ class PowerControlCommand : public DevControlCommand {
 public:
     explicit PowerControlCommand(const uint64_t target_address = 0, const uint64_t router_address = 0);
 
-    virtual String getCommandName();
+    virtual String getCommandName() const;
 
     virtual bool handleResponse(InverterAbstract* inverter, const fragment_t fragment[], const uint8_t max_fragment_id);
     virtual void gotTimeout(InverterAbstract* inverter);
diff --git a/lib/Hoymiles/src/commands/RealTimeRunDataCommand.cpp b/lib/Hoymiles/src/commands/RealTimeRunDataCommand.cpp
index cd38a5d..8e1c8dd 100644
--- a/lib/Hoymiles/src/commands/RealTimeRunDataCommand.cpp
+++ b/lib/Hoymiles/src/commands/RealTimeRunDataCommand.cpp
@@ -30,7 +30,7 @@ RealTimeRunDataCommand::RealTimeRunDataCommand(const uint64_t target_address, co
     setTimeout(500);
 }
 
-String RealTimeRunDataCommand::getCommandName()
+String RealTimeRunDataCommand::getCommandName() const
 {
     return "RealTimeRunData";
 }
diff --git a/lib/Hoymiles/src/commands/RealTimeRunDataCommand.h b/lib/Hoymiles/src/commands/RealTimeRunDataCommand.h
index b5b5d6c..fe4309a 100644
--- a/lib/Hoymiles/src/commands/RealTimeRunDataCommand.h
+++ b/lib/Hoymiles/src/commands/RealTimeRunDataCommand.h
@@ -7,7 +7,7 @@ class RealTimeRunDataCommand : public MultiDataCommand {
 public:
     explicit RealTimeRunDataCommand(const uint64_t target_address = 0, const uint64_t router_address = 0, const time_t time = 0);
 
-    virtual String getCommandName();
+    virtual String getCommandName() const;
 
     virtual bool handleResponse(InverterAbstract* inverter, const fragment_t fragment[], const uint8_t max_fragment_id);
     virtual void gotTimeout(InverterAbstract* inverter);
diff --git a/lib/Hoymiles/src/commands/RequestFrameCommand.cpp b/lib/Hoymiles/src/commands/RequestFrameCommand.cpp
index f88e51d..832dfae 100644
--- a/lib/Hoymiles/src/commands/RequestFrameCommand.cpp
+++ b/lib/Hoymiles/src/commands/RequestFrameCommand.cpp
@@ -32,7 +32,7 @@ RequestFrameCommand::RequestFrameCommand(const uint64_t target_address, const ui
     _payload_size = 10;
 }
 
-String RequestFrameCommand::getCommandName()
+String RequestFrameCommand::getCommandName() const
 {
     return "RequestFrame";
 }
@@ -42,7 +42,7 @@ void RequestFrameCommand::setFrameNo(const uint8_t frame_no)
     _payload[9] = frame_no | 0x80;
 }
 
-uint8_t RequestFrameCommand::getFrameNo()
+uint8_t RequestFrameCommand::getFrameNo() const
 {
     return _payload[9] & (~0x80);
 }
diff --git a/lib/Hoymiles/src/commands/RequestFrameCommand.h b/lib/Hoymiles/src/commands/RequestFrameCommand.h
index 2856b89..6ac40c9 100644
--- a/lib/Hoymiles/src/commands/RequestFrameCommand.h
+++ b/lib/Hoymiles/src/commands/RequestFrameCommand.h
@@ -7,10 +7,10 @@ class RequestFrameCommand : public SingleDataCommand {
 public:
     explicit RequestFrameCommand(const uint64_t target_address = 0, const uint64_t router_address = 0, uint8_t frame_no = 0);
 
-    virtual String getCommandName();
+    virtual String getCommandName() const;
 
     void setFrameNo(const uint8_t frame_no);
-    uint8_t getFrameNo();
+    uint8_t getFrameNo() const;
 
     virtual bool handleResponse(InverterAbstract* inverter, const fragment_t fragment[], const uint8_t max_fragment_id);
 };
\ No newline at end of file
diff --git a/lib/Hoymiles/src/commands/SystemConfigParaCommand.cpp b/lib/Hoymiles/src/commands/SystemConfigParaCommand.cpp
index 541bd63..6c5fe1f 100644
--- a/lib/Hoymiles/src/commands/SystemConfigParaCommand.cpp
+++ b/lib/Hoymiles/src/commands/SystemConfigParaCommand.cpp
@@ -30,7 +30,7 @@ SystemConfigParaCommand::SystemConfigParaCommand(const uint64_t target_address,
     setTimeout(200);
 }
 
-String SystemConfigParaCommand::getCommandName()
+String SystemConfigParaCommand::getCommandName() const
 {
     return "SystemConfigPara";
 }
diff --git a/lib/Hoymiles/src/commands/SystemConfigParaCommand.h b/lib/Hoymiles/src/commands/SystemConfigParaCommand.h
index 1520fd3..a5a750b 100644
--- a/lib/Hoymiles/src/commands/SystemConfigParaCommand.h
+++ b/lib/Hoymiles/src/commands/SystemConfigParaCommand.h
@@ -7,7 +7,7 @@ class SystemConfigParaCommand : public MultiDataCommand {
 public:
     explicit SystemConfigParaCommand(const uint64_t target_address = 0, const uint64_t router_address = 0, const time_t time = 0);
 
-    virtual String getCommandName();
+    virtual String getCommandName() const;
 
     virtual bool handleResponse(InverterAbstract* inverter, const fragment_t fragment[], const uint8_t max_fragment_id);
     virtual void gotTimeout(InverterAbstract* inverter);
diff --git a/lib/Hoymiles/src/inverters/HMS_1CH.cpp b/lib/Hoymiles/src/inverters/HMS_1CH.cpp
index c6e463e..312cf63 100644
--- a/lib/Hoymiles/src/inverters/HMS_1CH.cpp
+++ b/lib/Hoymiles/src/inverters/HMS_1CH.cpp
@@ -38,17 +38,17 @@ bool HMS_1CH::isValidSerial(const uint64_t serial)
     return preSerial == 0x1124;
 }
 
-String HMS_1CH::typeName()
+String HMS_1CH::typeName() const
 {
     return "HMS-300/350/400/450/500-1T";
 }
 
-const byteAssign_t* HMS_1CH::getByteAssignment()
+const byteAssign_t* HMS_1CH::getByteAssignment() const
 {
     return byteAssignment;
 }
 
-uint8_t HMS_1CH::getByteAssignmentSize()
+uint8_t HMS_1CH::getByteAssignmentSize() const
 {
     return sizeof(byteAssignment) / sizeof(byteAssignment[0]);
 }
\ No newline at end of file
diff --git a/lib/Hoymiles/src/inverters/HMS_1CH.h b/lib/Hoymiles/src/inverters/HMS_1CH.h
index 0ec9226..a5a64c1 100644
--- a/lib/Hoymiles/src/inverters/HMS_1CH.h
+++ b/lib/Hoymiles/src/inverters/HMS_1CH.h
@@ -8,7 +8,7 @@ class HMS_1CH : public HMS_Abstract {
 public:
     explicit HMS_1CH(HoymilesRadio* radio, const uint64_t serial);
     static bool isValidSerial(const uint64_t serial);
-    String typeName();
-    const byteAssign_t* getByteAssignment();
-    uint8_t getByteAssignmentSize();
+    String typeName() const;
+    const byteAssign_t* getByteAssignment() const;
+    uint8_t getByteAssignmentSize() const;
 };
\ No newline at end of file
diff --git a/lib/Hoymiles/src/inverters/HMS_1CHv2.cpp b/lib/Hoymiles/src/inverters/HMS_1CHv2.cpp
index efb396b..b6a9d93 100644
--- a/lib/Hoymiles/src/inverters/HMS_1CHv2.cpp
+++ b/lib/Hoymiles/src/inverters/HMS_1CHv2.cpp
@@ -38,17 +38,17 @@ bool HMS_1CHv2::isValidSerial(const uint64_t serial)
     return preSerial == 0x1125;
 }
 
-String HMS_1CHv2::typeName()
+String HMS_1CHv2::typeName() const
 {
     return "HMS-500-1T v2";
 }
 
-const byteAssign_t* HMS_1CHv2::getByteAssignment()
+const byteAssign_t* HMS_1CHv2::getByteAssignment() const
 {
     return byteAssignment;
 }
 
-uint8_t HMS_1CHv2::getByteAssignmentSize()
+uint8_t HMS_1CHv2::getByteAssignmentSize() const
 {
     return sizeof(byteAssignment) / sizeof(byteAssignment[0]);
 }
\ No newline at end of file
diff --git a/lib/Hoymiles/src/inverters/HMS_1CHv2.h b/lib/Hoymiles/src/inverters/HMS_1CHv2.h
index 42ff56c..c831d12 100644
--- a/lib/Hoymiles/src/inverters/HMS_1CHv2.h
+++ b/lib/Hoymiles/src/inverters/HMS_1CHv2.h
@@ -8,7 +8,7 @@ class HMS_1CHv2 : public HMS_Abstract {
 public:
     explicit HMS_1CHv2(HoymilesRadio* radio, const uint64_t serial);
     static bool isValidSerial(const uint64_t serial);
-    String typeName();
-    const byteAssign_t* getByteAssignment();
-    uint8_t getByteAssignmentSize();
+    String typeName() const;
+    const byteAssign_t* getByteAssignment() const;
+    uint8_t getByteAssignmentSize() const;
 };
\ No newline at end of file
diff --git a/lib/Hoymiles/src/inverters/HMS_2CH.cpp b/lib/Hoymiles/src/inverters/HMS_2CH.cpp
index f2cebb6..d038e77 100644
--- a/lib/Hoymiles/src/inverters/HMS_2CH.cpp
+++ b/lib/Hoymiles/src/inverters/HMS_2CH.cpp
@@ -45,17 +45,17 @@ bool HMS_2CH::isValidSerial(const uint64_t serial)
     return preSerial == 0x1144;
 }
 
-String HMS_2CH::typeName()
+String HMS_2CH::typeName() const
 {
     return "HMS-600/700/800/900/1000-2T";
 }
 
-const byteAssign_t* HMS_2CH::getByteAssignment()
+const byteAssign_t* HMS_2CH::getByteAssignment() const
 {
     return byteAssignment;
 }
 
-uint8_t HMS_2CH::getByteAssignmentSize()
+uint8_t HMS_2CH::getByteAssignmentSize() const
 {
     return sizeof(byteAssignment) / sizeof(byteAssignment[0]);
 }
\ No newline at end of file
diff --git a/lib/Hoymiles/src/inverters/HMS_2CH.h b/lib/Hoymiles/src/inverters/HMS_2CH.h
index 3b7bc5a..9f1ed91 100644
--- a/lib/Hoymiles/src/inverters/HMS_2CH.h
+++ b/lib/Hoymiles/src/inverters/HMS_2CH.h
@@ -8,7 +8,7 @@ class HMS_2CH : public HMS_Abstract {
 public:
     explicit HMS_2CH(HoymilesRadio* radio, const uint64_t serial);
     static bool isValidSerial(const uint64_t serial);
-    String typeName();
-    const byteAssign_t* getByteAssignment();
-    uint8_t getByteAssignmentSize();
+    String typeName() const;
+    const byteAssign_t* getByteAssignment() const;
+    uint8_t getByteAssignmentSize() const;
 };
\ No newline at end of file
diff --git a/lib/Hoymiles/src/inverters/HMS_4CH.cpp b/lib/Hoymiles/src/inverters/HMS_4CH.cpp
index 721a322..eff44ab 100644
--- a/lib/Hoymiles/src/inverters/HMS_4CH.cpp
+++ b/lib/Hoymiles/src/inverters/HMS_4CH.cpp
@@ -59,17 +59,17 @@ bool HMS_4CH::isValidSerial(const uint64_t serial)
     return preSerial == 0x1164;
 }
 
-String HMS_4CH::typeName()
+String HMS_4CH::typeName() const
 {
     return "HMS-1600/1800/2000-4T";
 }
 
-const byteAssign_t* HMS_4CH::getByteAssignment()
+const byteAssign_t* HMS_4CH::getByteAssignment() const
 {
     return byteAssignment;
 }
 
-uint8_t HMS_4CH::getByteAssignmentSize()
+uint8_t HMS_4CH::getByteAssignmentSize() const
 {
     return sizeof(byteAssignment) / sizeof(byteAssignment[0]);
 }
\ No newline at end of file
diff --git a/lib/Hoymiles/src/inverters/HMS_4CH.h b/lib/Hoymiles/src/inverters/HMS_4CH.h
index 706b1f3..9d49de0 100644
--- a/lib/Hoymiles/src/inverters/HMS_4CH.h
+++ b/lib/Hoymiles/src/inverters/HMS_4CH.h
@@ -7,7 +7,7 @@ class HMS_4CH : public HMS_Abstract {
 public:
     explicit HMS_4CH(HoymilesRadio* radio, const uint64_t serial);
     static bool isValidSerial(const uint64_t serial);
-    String typeName();
-    const byteAssign_t* getByteAssignment();
-    uint8_t getByteAssignmentSize();
+    String typeName() const;
+    const byteAssign_t* getByteAssignment() const;
+    uint8_t getByteAssignmentSize() const;
 };
\ No newline at end of file
diff --git a/lib/Hoymiles/src/inverters/HMT_4CH.cpp b/lib/Hoymiles/src/inverters/HMT_4CH.cpp
index 4483732..717099b 100644
--- a/lib/Hoymiles/src/inverters/HMT_4CH.cpp
+++ b/lib/Hoymiles/src/inverters/HMT_4CH.cpp
@@ -68,17 +68,17 @@ bool HMT_4CH::isValidSerial(const uint64_t serial)
     return preSerial == 0x1361;
 }
 
-String HMT_4CH::typeName()
+String HMT_4CH::typeName() const
 {
     return F("HMT-1600/1800/2000-4T");
 }
 
-const byteAssign_t* HMT_4CH::getByteAssignment()
+const byteAssign_t* HMT_4CH::getByteAssignment() const
 {
     return byteAssignment;
 }
 
-uint8_t HMT_4CH::getByteAssignmentSize()
+uint8_t HMT_4CH::getByteAssignmentSize() const
 {
     return sizeof(byteAssignment) / sizeof(byteAssignment[0]);
 }
diff --git a/lib/Hoymiles/src/inverters/HMT_4CH.h b/lib/Hoymiles/src/inverters/HMT_4CH.h
index 07949e7..01d3289 100644
--- a/lib/Hoymiles/src/inverters/HMT_4CH.h
+++ b/lib/Hoymiles/src/inverters/HMT_4CH.h
@@ -7,7 +7,7 @@ class HMT_4CH : public HMT_Abstract {
 public:
     explicit HMT_4CH(HoymilesRadio* radio, const uint64_t serial);
     static bool isValidSerial(const uint64_t serial);
-    String typeName();
-    const byteAssign_t* getByteAssignment();
-    uint8_t getByteAssignmentSize();
+    String typeName() const;
+    const byteAssign_t* getByteAssignment() const;
+    uint8_t getByteAssignmentSize() const;
 };
\ No newline at end of file
diff --git a/lib/Hoymiles/src/inverters/HMT_6CH.cpp b/lib/Hoymiles/src/inverters/HMT_6CH.cpp
index 9e0758e..6cbd209 100644
--- a/lib/Hoymiles/src/inverters/HMT_6CH.cpp
+++ b/lib/Hoymiles/src/inverters/HMT_6CH.cpp
@@ -82,17 +82,17 @@ bool HMT_6CH::isValidSerial(const uint64_t serial)
     return preSerial == 0x1382;
 }
 
-String HMT_6CH::typeName()
+String HMT_6CH::typeName() const
 {
     return F("HMT-1800/2250-6T");
 }
 
-const byteAssign_t* HMT_6CH::getByteAssignment()
+const byteAssign_t* HMT_6CH::getByteAssignment() const
 {
     return byteAssignment;
 }
 
-uint8_t HMT_6CH::getByteAssignmentSize()
+uint8_t HMT_6CH::getByteAssignmentSize() const
 {
     return sizeof(byteAssignment) / sizeof(byteAssignment[0]);
 }
diff --git a/lib/Hoymiles/src/inverters/HMT_6CH.h b/lib/Hoymiles/src/inverters/HMT_6CH.h
index e1d934e..6b72800 100644
--- a/lib/Hoymiles/src/inverters/HMT_6CH.h
+++ b/lib/Hoymiles/src/inverters/HMT_6CH.h
@@ -7,7 +7,7 @@ class HMT_6CH : public HMT_Abstract {
 public:
     explicit HMT_6CH(HoymilesRadio* radio, const uint64_t serial);
     static bool isValidSerial(const uint64_t serial);
-    String typeName();
-    const byteAssign_t* getByteAssignment();
-    uint8_t getByteAssignmentSize();
+    String typeName() const;
+    const byteAssign_t* getByteAssignment() const;
+    uint8_t getByteAssignmentSize() const;
 };
\ No newline at end of file
diff --git a/lib/Hoymiles/src/inverters/HM_1CH.cpp b/lib/Hoymiles/src/inverters/HM_1CH.cpp
index 463658f..7b23207 100644
--- a/lib/Hoymiles/src/inverters/HM_1CH.cpp
+++ b/lib/Hoymiles/src/inverters/HM_1CH.cpp
@@ -51,17 +51,17 @@ bool HM_1CH::isValidSerial(const uint64_t serial)
     return false;
 }
 
-String HM_1CH::typeName()
+String HM_1CH::typeName() const
 {
     return "HM-300/350/400-1T";
 }
 
-const byteAssign_t* HM_1CH::getByteAssignment()
+const byteAssign_t* HM_1CH::getByteAssignment() const
 {
     return byteAssignment;
 }
 
-uint8_t HM_1CH::getByteAssignmentSize()
+uint8_t HM_1CH::getByteAssignmentSize() const
 {
     return sizeof(byteAssignment) / sizeof(byteAssignment[0]);
 }
\ No newline at end of file
diff --git a/lib/Hoymiles/src/inverters/HM_1CH.h b/lib/Hoymiles/src/inverters/HM_1CH.h
index fd6cb76..a35b4e5 100644
--- a/lib/Hoymiles/src/inverters/HM_1CH.h
+++ b/lib/Hoymiles/src/inverters/HM_1CH.h
@@ -8,7 +8,7 @@ class HM_1CH : public HM_Abstract {
 public:
     explicit HM_1CH(HoymilesRadio* radio, const uint64_t serial);
     static bool isValidSerial(const uint64_t serial);
-    String typeName();
-    const byteAssign_t* getByteAssignment();
-    uint8_t getByteAssignmentSize();
+    String typeName() const;
+    const byteAssign_t* getByteAssignment() const;
+    uint8_t getByteAssignmentSize() const;
 };
\ No newline at end of file
diff --git a/lib/Hoymiles/src/inverters/HM_2CH.cpp b/lib/Hoymiles/src/inverters/HM_2CH.cpp
index 9a251f2..2f56ec3 100644
--- a/lib/Hoymiles/src/inverters/HM_2CH.cpp
+++ b/lib/Hoymiles/src/inverters/HM_2CH.cpp
@@ -59,17 +59,17 @@ bool HM_2CH::isValidSerial(const uint64_t serial)
     return false;
 }
 
-String HM_2CH::typeName()
+String HM_2CH::typeName() const
 {
     return "HM-600/700/800-2T";
 }
 
-const byteAssign_t* HM_2CH::getByteAssignment()
+const byteAssign_t* HM_2CH::getByteAssignment() const
 {
     return byteAssignment;
 }
 
-uint8_t HM_2CH::getByteAssignmentSize()
+uint8_t HM_2CH::getByteAssignmentSize() const
 {
     return sizeof(byteAssignment) / sizeof(byteAssignment[0]);
 }
\ No newline at end of file
diff --git a/lib/Hoymiles/src/inverters/HM_2CH.h b/lib/Hoymiles/src/inverters/HM_2CH.h
index fb3c1d6..1fd5449 100644
--- a/lib/Hoymiles/src/inverters/HM_2CH.h
+++ b/lib/Hoymiles/src/inverters/HM_2CH.h
@@ -7,7 +7,7 @@ class HM_2CH : public HM_Abstract {
 public:
     explicit HM_2CH(HoymilesRadio* radio, const uint64_t serial);
     static bool isValidSerial(const uint64_t serial);
-    String typeName();
-    const byteAssign_t* getByteAssignment();
-    uint8_t getByteAssignmentSize();
+    String typeName() const;
+    const byteAssign_t* getByteAssignment() const;
+    uint8_t getByteAssignmentSize() const;
 };
\ No newline at end of file
diff --git a/lib/Hoymiles/src/inverters/HM_4CH.cpp b/lib/Hoymiles/src/inverters/HM_4CH.cpp
index 446581f..bcad253 100644
--- a/lib/Hoymiles/src/inverters/HM_4CH.cpp
+++ b/lib/Hoymiles/src/inverters/HM_4CH.cpp
@@ -72,17 +72,17 @@ bool HM_4CH::isValidSerial(const uint64_t serial)
     return false;
 }
 
-String HM_4CH::typeName()
+String HM_4CH::typeName() const
 {
     return "HM-1000/1200/1500-4T";
 }
 
-const byteAssign_t* HM_4CH::getByteAssignment()
+const byteAssign_t* HM_4CH::getByteAssignment() const
 {
     return byteAssignment;
 }
 
-uint8_t HM_4CH::getByteAssignmentSize()
+uint8_t HM_4CH::getByteAssignmentSize() const
 {
     return sizeof(byteAssignment) / sizeof(byteAssignment[0]);
 }
\ No newline at end of file
diff --git a/lib/Hoymiles/src/inverters/HM_4CH.h b/lib/Hoymiles/src/inverters/HM_4CH.h
index 3cd822c..e54f332 100644
--- a/lib/Hoymiles/src/inverters/HM_4CH.h
+++ b/lib/Hoymiles/src/inverters/HM_4CH.h
@@ -7,7 +7,7 @@ class HM_4CH : public HM_Abstract {
 public:
     explicit HM_4CH(HoymilesRadio* radio, const uint64_t serial);
     static bool isValidSerial(const uint64_t serial);
-    String typeName();
-    const byteAssign_t* getByteAssignment();
-    uint8_t getByteAssignmentSize();
+    String typeName() const;
+    const byteAssign_t* getByteAssignment() const;
+    uint8_t getByteAssignmentSize() const;
 };
\ No newline at end of file
diff --git a/lib/Hoymiles/src/inverters/InverterAbstract.cpp b/lib/Hoymiles/src/inverters/InverterAbstract.cpp
index 45aded8..4267680 100644
--- a/lib/Hoymiles/src/inverters/InverterAbstract.cpp
+++ b/lib/Hoymiles/src/inverters/InverterAbstract.cpp
@@ -35,12 +35,12 @@ void InverterAbstract::init()
     _statisticsParser.get()->setByteAssignment(getByteAssignment(), getByteAssignmentSize());
 }
 
-uint64_t InverterAbstract::serial()
+uint64_t InverterAbstract::serial() const
 {
     return _serial.u64;
 }
 
-const String& InverterAbstract::serialString()
+const String& InverterAbstract::serialString() const
 {
     return _serialString;
 }
@@ -55,7 +55,7 @@ void InverterAbstract::setName(const char* name)
     _name[len] = '\0';
 }
 
-const char* InverterAbstract::name()
+const char* InverterAbstract::name() const
 {
     return _name;
 }
@@ -82,7 +82,7 @@ void InverterAbstract::setEnablePolling(const bool enabled)
     _enablePolling = enabled;
 }
 
-bool InverterAbstract::getEnablePolling()
+bool InverterAbstract::getEnablePolling() const
 {
     return _enablePolling;
 }
@@ -92,7 +92,7 @@ void InverterAbstract::setEnableCommands(const bool enabled)
     _enableCommands = enabled;
 }
 
-bool InverterAbstract::getEnableCommands()
+bool InverterAbstract::getEnableCommands() const
 {
     return _enableCommands;
 }
@@ -102,7 +102,7 @@ void InverterAbstract::setReachableThreshold(const uint8_t threshold)
     _reachableThreshold = threshold;
 }
 
-uint8_t InverterAbstract::getReachableThreshold()
+uint8_t InverterAbstract::getReachableThreshold() const
 {
     return _reachableThreshold;
 }
@@ -112,7 +112,7 @@ void InverterAbstract::setZeroValuesIfUnreachable(const bool enabled)
     _zeroValuesIfUnreachable = enabled;
 }
 
-bool InverterAbstract::getZeroValuesIfUnreachable()
+bool InverterAbstract::getZeroValuesIfUnreachable() const
 {
     return _zeroValuesIfUnreachable;
 }
@@ -122,7 +122,7 @@ void InverterAbstract::setZeroYieldDayOnMidnight(const bool enabled)
     _zeroYieldDayOnMidnight = enabled;
 }
 
-bool InverterAbstract::getZeroYieldDayOnMidnight()
+bool InverterAbstract::getZeroYieldDayOnMidnight() const
 {
     return _zeroYieldDayOnMidnight;
 }
diff --git a/lib/Hoymiles/src/inverters/InverterAbstract.h b/lib/Hoymiles/src/inverters/InverterAbstract.h
index 6ffc3f9..d2fdb21 100644
--- a/lib/Hoymiles/src/inverters/InverterAbstract.h
+++ b/lib/Hoymiles/src/inverters/InverterAbstract.h
@@ -32,31 +32,31 @@ class InverterAbstract {
 public:
     explicit InverterAbstract(HoymilesRadio* radio, const uint64_t serial);
     void init();
-    uint64_t serial();
-    const String& serialString();
+    uint64_t serial() const;
+    const String& serialString() const;
     void setName(const char* name);
-    const char* name();
-    virtual String typeName() = 0;
-    virtual const byteAssign_t* getByteAssignment() = 0;
-    virtual uint8_t getByteAssignmentSize() = 0;
+    const char* name() const;
+    virtual String typeName() const = 0;
+    virtual const byteAssign_t* getByteAssignment() const = 0;
+    virtual uint8_t getByteAssignmentSize() const = 0;
 
     bool isProducing();
     bool isReachable();
 
     void setEnablePolling(const bool enabled);
-    bool getEnablePolling();
+    bool getEnablePolling() const;
 
     void setEnableCommands(const bool enabled);
-    bool getEnableCommands();
+    bool getEnableCommands() const;
 
     void setReachableThreshold(const uint8_t threshold);
-    uint8_t getReachableThreshold();
+    uint8_t getReachableThreshold() const;
 
     void setZeroValuesIfUnreachable(const bool enabled);
-    bool getZeroValuesIfUnreachable();
+    bool getZeroValuesIfUnreachable() const;
 
     void setZeroYieldDayOnMidnight(const bool enabled);
-    bool getZeroYieldDayOnMidnight();
+    bool getZeroYieldDayOnMidnight() const;
 
     void clearRxFragmentBuffer();
     void addRxFragment(const uint8_t fragment[], const uint8_t len);
diff --git a/lib/Hoymiles/src/parser/AlarmLogParser.cpp b/lib/Hoymiles/src/parser/AlarmLogParser.cpp
index ad7db85..415dd1b 100644
--- a/lib/Hoymiles/src/parser/AlarmLogParser.cpp
+++ b/lib/Hoymiles/src/parser/AlarmLogParser.cpp
@@ -191,7 +191,7 @@ void AlarmLogParser::appendFragment(const uint8_t offset, const uint8_t* payload
     _alarmLogLength += len;
 }
 
-uint8_t AlarmLogParser::getEntryCount()
+uint8_t AlarmLogParser::getEntryCount() const
 {
     if (_alarmLogLength < 2) {
         return 0;
@@ -204,7 +204,7 @@ void AlarmLogParser::setLastAlarmRequestSuccess(const LastCommandSuccess status)
     _lastAlarmRequestSuccess = status;
 }
 
-LastCommandSuccess AlarmLogParser::getLastAlarmRequestSuccess()
+LastCommandSuccess AlarmLogParser::getLastAlarmRequestSuccess() const
 {
     return _lastAlarmRequestSuccess;
 }
@@ -266,7 +266,7 @@ void AlarmLogParser::getLogEntry(const uint8_t entryId, AlarmLogEntry_t* entry,
     }
 }
 
-String AlarmLogParser::getLocaleMessage(const AlarmMessage_t* msg, const AlarmMessageLocale_t locale)
+String AlarmLogParser::getLocaleMessage(const AlarmMessage_t* msg, const AlarmMessageLocale_t locale) const
 {
     if (locale == AlarmMessageLocale_t::DE) {
         return msg->Message_de[0] != '\0' ? msg->Message_de : msg->Message_en;
diff --git a/lib/Hoymiles/src/parser/AlarmLogParser.h b/lib/Hoymiles/src/parser/AlarmLogParser.h
index 2477af5..2c4264b 100644
--- a/lib/Hoymiles/src/parser/AlarmLogParser.h
+++ b/lib/Hoymiles/src/parser/AlarmLogParser.h
@@ -42,17 +42,17 @@ public:
     void clearBuffer();
     void appendFragment(const uint8_t offset, const uint8_t* payload, const uint8_t len);
 
-    uint8_t getEntryCount();
+    uint8_t getEntryCount() const;
     void getLogEntry(const uint8_t entryId, AlarmLogEntry_t* entry, const AlarmMessageLocale_t locale = AlarmMessageLocale_t::EN);
 
     void setLastAlarmRequestSuccess(const LastCommandSuccess status);
-    LastCommandSuccess getLastAlarmRequestSuccess();
+    LastCommandSuccess getLastAlarmRequestSuccess() const;
 
     void setMessageType(const AlarmMessageType_t type);
 
 private:
     static int getTimezoneOffset();
-    String getLocaleMessage(const AlarmMessage_t* msg, const AlarmMessageLocale_t locale);
+    String getLocaleMessage(const AlarmMessage_t* msg, const AlarmMessageLocale_t locale) const;
 
     uint8_t _payloadAlarmLog[ALARM_LOG_PAYLOAD_SIZE];
     uint8_t _alarmLogLength = 0;
diff --git a/lib/Hoymiles/src/parser/DevInfoParser.cpp b/lib/Hoymiles/src/parser/DevInfoParser.cpp
index 59cb523..d4f5990 100644
--- a/lib/Hoymiles/src/parser/DevInfoParser.cpp
+++ b/lib/Hoymiles/src/parser/DevInfoParser.cpp
@@ -91,7 +91,7 @@ void DevInfoParser::appendFragmentSimple(const uint8_t offset, const uint8_t* pa
     _devInfoSimpleLength += len;
 }
 
-uint32_t DevInfoParser::getLastUpdateAll()
+uint32_t DevInfoParser::getLastUpdateAll() const
 {
     return _lastUpdateAll;
 }
@@ -102,7 +102,7 @@ void DevInfoParser::setLastUpdateAll(const uint32_t lastUpdate)
     setLastUpdate(lastUpdate);
 }
 
-uint32_t DevInfoParser::getLastUpdateSimple()
+uint32_t DevInfoParser::getLastUpdateSimple() const
 {
     return _lastUpdateSimple;
 }
@@ -113,7 +113,7 @@ void DevInfoParser::setLastUpdateSimple(const uint32_t lastUpdate)
     setLastUpdate(lastUpdate);
 }
 
-uint16_t DevInfoParser::getFwBuildVersion()
+uint16_t DevInfoParser::getFwBuildVersion() const
 {
     HOY_SEMAPHORE_TAKE();
     const uint16_t ret = (((uint16_t)_payloadDevInfoAll[0]) << 8) | _payloadDevInfoAll[1];
@@ -121,7 +121,7 @@ uint16_t DevInfoParser::getFwBuildVersion()
     return ret;
 }
 
-time_t DevInfoParser::getFwBuildDateTime()
+time_t DevInfoParser::getFwBuildDateTime() const
 {
     struct tm timeinfo = {};
     HOY_SEMAPHORE_TAKE();
@@ -137,7 +137,7 @@ time_t DevInfoParser::getFwBuildDateTime()
     return timegm(&timeinfo);
 }
 
-uint16_t DevInfoParser::getFwBootloaderVersion()
+uint16_t DevInfoParser::getFwBootloaderVersion() const
 {
     HOY_SEMAPHORE_TAKE();
     const uint16_t ret = (((uint16_t)_payloadDevInfoAll[8]) << 8) | _payloadDevInfoAll[9];
@@ -145,7 +145,7 @@ uint16_t DevInfoParser::getFwBootloaderVersion()
     return ret;
 }
 
-uint32_t DevInfoParser::getHwPartNumber()
+uint32_t DevInfoParser::getHwPartNumber() const
 {
     HOY_SEMAPHORE_TAKE();
     const uint16_t hwpn_h = (((uint16_t)_payloadDevInfoSimple[2]) << 8) | _payloadDevInfoSimple[3];
@@ -155,7 +155,7 @@ uint32_t DevInfoParser::getHwPartNumber()
     return ((uint32_t)hwpn_h << 16) | ((uint32_t)hwpn_l);
 }
 
-String DevInfoParser::getHwVersion()
+String DevInfoParser::getHwVersion() const
 {
     char buf[8];
     HOY_SEMAPHORE_TAKE();
@@ -164,7 +164,7 @@ String DevInfoParser::getHwVersion()
     return buf;
 }
 
-uint16_t DevInfoParser::getMaxPower()
+uint16_t DevInfoParser::getMaxPower() const
 {
     const uint8_t idx = getDevIdx();
     if (idx == 0xff) {
@@ -173,7 +173,7 @@ uint16_t DevInfoParser::getMaxPower()
     return devInfo[idx].maxPower;
 }
 
-String DevInfoParser::getHwModelName()
+String DevInfoParser::getHwModelName() const
 {
     const uint8_t idx = getDevIdx();
     if (idx == 0xff) {
@@ -182,7 +182,7 @@ String DevInfoParser::getHwModelName()
     return devInfo[idx].modelName;
 }
 
-bool DevInfoParser::containsValidData()
+bool DevInfoParser::containsValidData() const
 {
     const time_t t = getFwBuildDateTime();
 
@@ -192,7 +192,7 @@ bool DevInfoParser::containsValidData()
     return info.tm_year > (2016 - 1900);
 }
 
-uint8_t DevInfoParser::getDevIdx()
+uint8_t DevInfoParser::getDevIdx() const
 {
     uint8_t ret = 0xff;
     uint8_t pos;
diff --git a/lib/Hoymiles/src/parser/DevInfoParser.h b/lib/Hoymiles/src/parser/DevInfoParser.h
index 2225301..89c40f8 100644
--- a/lib/Hoymiles/src/parser/DevInfoParser.h
+++ b/lib/Hoymiles/src/parser/DevInfoParser.h
@@ -13,27 +13,27 @@ public:
     void clearBufferSimple();
     void appendFragmentSimple(const uint8_t offset, const uint8_t* payload, const uint8_t len);
 
-    uint32_t getLastUpdateAll();
+    uint32_t getLastUpdateAll() const;
     void setLastUpdateAll(const uint32_t lastUpdate);
 
-    uint32_t getLastUpdateSimple();
+    uint32_t getLastUpdateSimple() const;
     void setLastUpdateSimple(const uint32_t lastUpdate);
 
-    uint16_t getFwBuildVersion();
-    time_t getFwBuildDateTime();
-    uint16_t getFwBootloaderVersion();
+    uint16_t getFwBuildVersion() const;
+    time_t getFwBuildDateTime() const;
+    uint16_t getFwBootloaderVersion() const;
 
-    uint32_t getHwPartNumber();
-    String getHwVersion();
+    uint32_t getHwPartNumber() const;
+    String getHwVersion() const;
 
-    uint16_t getMaxPower();
-    String getHwModelName();
+    uint16_t getMaxPower() const;
+    String getHwModelName() const;
 
-    bool containsValidData();
+    bool containsValidData() const;
 
 private:
-    time_t timegm(const struct tm* tm);
-    uint8_t getDevIdx();
+    static time_t timegm(const struct tm* tm);
+    uint8_t getDevIdx() const;
 
     uint32_t _lastUpdateAll = 0;
     uint32_t _lastUpdateSimple = 0;
diff --git a/lib/Hoymiles/src/parser/GridProfileParser.cpp b/lib/Hoymiles/src/parser/GridProfileParser.cpp
index d523715..9bd0dd6 100644
--- a/lib/Hoymiles/src/parser/GridProfileParser.cpp
+++ b/lib/Hoymiles/src/parser/GridProfileParser.cpp
@@ -297,7 +297,7 @@ void GridProfileParser::appendFragment(const uint8_t offset, const uint8_t* payl
     _gridProfileLength += len;
 }
 
-String GridProfileParser::getProfileName()
+String GridProfileParser::getProfileName() const
 {
     for (auto& ptype : _profileTypes) {
         if (ptype.lIdx == _payloadGridProfile[0] && ptype.hIdx == _payloadGridProfile[1]) {
@@ -307,7 +307,7 @@ String GridProfileParser::getProfileName()
     return "Unknown";
 }
 
-String GridProfileParser::getProfileVersion()
+String GridProfileParser::getProfileVersion() const
 {
     char buffer[10];
     HOY_SEMAPHORE_TAKE();
@@ -316,7 +316,7 @@ String GridProfileParser::getProfileVersion()
     return buffer;
 }
 
-std::vector<uint8_t> GridProfileParser::getRawData()
+std::vector<uint8_t> GridProfileParser::getRawData() const
 {
     std::vector<uint8_t> ret;
     HOY_SEMAPHORE_TAKE();
@@ -327,7 +327,7 @@ std::vector<uint8_t> GridProfileParser::getRawData()
     return ret;
 }
 
-std::list<GridProfileSection_t> GridProfileParser::getProfile()
+std::list<GridProfileSection_t> GridProfileParser::getProfile() const
 {
     std::list<GridProfileSection_t> l;
 
diff --git a/lib/Hoymiles/src/parser/GridProfileParser.h b/lib/Hoymiles/src/parser/GridProfileParser.h
index 4178400..370463d 100644
--- a/lib/Hoymiles/src/parser/GridProfileParser.h
+++ b/lib/Hoymiles/src/parser/GridProfileParser.h
@@ -36,12 +36,12 @@ public:
     void clearBuffer();
     void appendFragment(const uint8_t offset, const uint8_t* payload, const uint8_t len);
 
-    String getProfileName();
-    String getProfileVersion();
+    String getProfileName() const;
+    String getProfileVersion() const;
 
-    std::vector<uint8_t> getRawData();
+    std::vector<uint8_t> getRawData() const;
 
-    std::list<GridProfileSection_t> getProfile();
+    std::list<GridProfileSection_t> getProfile() const;
 
 private:
     static uint8_t getSectionSize(const uint8_t section_id, const uint8_t section_version);
diff --git a/lib/Hoymiles/src/parser/Parser.cpp b/lib/Hoymiles/src/parser/Parser.cpp
index 450e585..96681ce 100644
--- a/lib/Hoymiles/src/parser/Parser.cpp
+++ b/lib/Hoymiles/src/parser/Parser.cpp
@@ -10,7 +10,7 @@ Parser::Parser()
     HOY_SEMAPHORE_GIVE(); // release before first use
 }
 
-uint32_t Parser::getLastUpdate()
+uint32_t Parser::getLastUpdate() const
 {
     return _lastUpdate;
 }
diff --git a/lib/Hoymiles/src/parser/Parser.h b/lib/Hoymiles/src/parser/Parser.h
index f2cdd1f..dda0ef8 100644
--- a/lib/Hoymiles/src/parser/Parser.h
+++ b/lib/Hoymiles/src/parser/Parser.h
@@ -17,7 +17,7 @@ typedef enum {
 class Parser {
 public:
     Parser();
-    uint32_t getLastUpdate();
+    uint32_t getLastUpdate() const;
     void setLastUpdate(const uint32_t lastUpdate);
 
     void beginAppendFragment();
diff --git a/lib/Hoymiles/src/parser/PowerCommandParser.cpp b/lib/Hoymiles/src/parser/PowerCommandParser.cpp
index dee97f3..dc8dc79 100644
--- a/lib/Hoymiles/src/parser/PowerCommandParser.cpp
+++ b/lib/Hoymiles/src/parser/PowerCommandParser.cpp
@@ -9,12 +9,12 @@ void PowerCommandParser::setLastPowerCommandSuccess(const LastCommandSuccess sta
     _lastLimitCommandSuccess = status;
 }
 
-LastCommandSuccess PowerCommandParser::getLastPowerCommandSuccess()
+LastCommandSuccess PowerCommandParser::getLastPowerCommandSuccess() const
 {
     return _lastLimitCommandSuccess;
 }
 
-uint32_t PowerCommandParser::getLastUpdateCommand()
+uint32_t PowerCommandParser::getLastUpdateCommand() const
 {
     return _lastUpdateCommand;
 }
diff --git a/lib/Hoymiles/src/parser/PowerCommandParser.h b/lib/Hoymiles/src/parser/PowerCommandParser.h
index eaefd4b..b448692 100644
--- a/lib/Hoymiles/src/parser/PowerCommandParser.h
+++ b/lib/Hoymiles/src/parser/PowerCommandParser.h
@@ -5,8 +5,8 @@
 class PowerCommandParser : public Parser {
 public:
     void setLastPowerCommandSuccess(const LastCommandSuccess status);
-    LastCommandSuccess getLastPowerCommandSuccess();
-    uint32_t getLastUpdateCommand();
+    LastCommandSuccess getLastPowerCommandSuccess() const;
+    uint32_t getLastUpdateCommand() const;
     void setLastUpdateCommand(const uint32_t lastUpdate);
 
 private:
diff --git a/lib/Hoymiles/src/parser/StatisticsParser.cpp b/lib/Hoymiles/src/parser/StatisticsParser.cpp
index c1cecf8..df6e585 100644
--- a/lib/Hoymiles/src/parser/StatisticsParser.cpp
+++ b/lib/Hoymiles/src/parser/StatisticsParser.cpp
@@ -121,7 +121,7 @@ void StatisticsParser::endAppendFragment()
     }
 }
 
-const byteAssign_t* StatisticsParser::getAssignmentByChannelField(const ChannelType_t type, const ChannelNum_t channel, const FieldId_t fieldId)
+const byteAssign_t* StatisticsParser::getAssignmentByChannelField(const ChannelType_t type, const ChannelNum_t channel, const FieldId_t fieldId) const
 {
     for (uint8_t i = 0; i < _byteAssignmentSize; i++) {
         if (_byteAssignment[i].type == type && _byteAssignment[i].ch == channel && _byteAssignment[i].fieldId == fieldId) {
@@ -233,25 +233,25 @@ String StatisticsParser::getChannelFieldValueString(const ChannelType_t type, co
         static_cast<unsigned int>(getChannelFieldDigits(type, channel, fieldId)));
 }
 
-bool StatisticsParser::hasChannelFieldValue(const ChannelType_t type, const ChannelNum_t channel, const FieldId_t fieldId)
+bool StatisticsParser::hasChannelFieldValue(const ChannelType_t type, const ChannelNum_t channel, const FieldId_t fieldId) const
 {
     const byteAssign_t* pos = getAssignmentByChannelField(type, channel, fieldId);
     return pos != nullptr;
 }
 
-const char* StatisticsParser::getChannelFieldUnit(const ChannelType_t type, const ChannelNum_t channel, const FieldId_t fieldId)
+const char* StatisticsParser::getChannelFieldUnit(const ChannelType_t type, const ChannelNum_t channel, const FieldId_t fieldId) const
 {
     const byteAssign_t* pos = getAssignmentByChannelField(type, channel, fieldId);
     return units[pos->unitId];
 }
 
-const char* StatisticsParser::getChannelFieldName(const ChannelType_t type, const ChannelNum_t channel, const FieldId_t fieldId)
+const char* StatisticsParser::getChannelFieldName(const ChannelType_t type, const ChannelNum_t channel, const FieldId_t fieldId) const
 {
     const byteAssign_t* pos = getAssignmentByChannelField(type, channel, fieldId);
     return fields[pos->fieldId];
 }
 
-uint8_t StatisticsParser::getChannelFieldDigits(const ChannelType_t type, const ChannelNum_t channel, const FieldId_t fieldId)
+uint8_t StatisticsParser::getChannelFieldDigits(const ChannelType_t type, const ChannelNum_t channel, const FieldId_t fieldId) const
 {
     const byteAssign_t* pos = getAssignmentByChannelField(type, channel, fieldId);
     return pos->digits;
@@ -276,7 +276,7 @@ void StatisticsParser::setChannelFieldOffset(const ChannelType_t type, const Cha
     }
 }
 
-std::list<ChannelType_t> StatisticsParser::getChannelTypes()
+std::list<ChannelType_t> StatisticsParser::getChannelTypes() const
 {
     return {
         TYPE_AC,
@@ -285,12 +285,12 @@ std::list<ChannelType_t> StatisticsParser::getChannelTypes()
     };
 }
 
-const char* StatisticsParser::getChannelTypeName(const ChannelType_t type)
+const char* StatisticsParser::getChannelTypeName(const ChannelType_t type) const
 {
     return channelsTypes[type];
 }
 
-std::list<ChannelNum_t> StatisticsParser::getChannelsByType(const ChannelType_t type)
+std::list<ChannelNum_t> StatisticsParser::getChannelsByType(const ChannelType_t type) const
 {
     std::list<ChannelNum_t> l;
     for (uint8_t i = 0; i < _byteAssignmentSize; i++) {
@@ -302,7 +302,7 @@ std::list<ChannelNum_t> StatisticsParser::getChannelsByType(const ChannelType_t
     return l;
 }
 
-uint16_t StatisticsParser::getStringMaxPower(const uint8_t channel)
+uint16_t StatisticsParser::getStringMaxPower(const uint8_t channel) const
 {
     return _stringMaxPower[channel];
 }
@@ -324,7 +324,7 @@ void StatisticsParser::incrementRxFailureCount()
     _rxFailureCount++;
 }
 
-uint32_t StatisticsParser::getRxFailureCount()
+uint32_t StatisticsParser::getRxFailureCount() const
 {
     return _rxFailureCount;
 }
@@ -345,7 +345,7 @@ void StatisticsParser::setLastUpdate(const uint32_t lastUpdate)
     setLastUpdateFromInternal(lastUpdate);
 }
 
-uint32_t StatisticsParser::getLastUpdateFromInternal()
+uint32_t StatisticsParser::getLastUpdateFromInternal() const
 {
     return _lastUpdateFromInternal;
 }
@@ -355,7 +355,7 @@ void StatisticsParser::setLastUpdateFromInternal(const uint32_t lastUpdate)
     _lastUpdateFromInternal = lastUpdate;
 }
 
-bool StatisticsParser::getYieldDayCorrection()
+bool StatisticsParser::getYieldDayCorrection() const
 {
     return _enableYieldDayCorrection;
 }
diff --git a/lib/Hoymiles/src/parser/StatisticsParser.h b/lib/Hoymiles/src/parser/StatisticsParser.h
index 9354628..2893cbd 100644
--- a/lib/Hoymiles/src/parser/StatisticsParser.h
+++ b/lib/Hoymiles/src/parser/StatisticsParser.h
@@ -113,31 +113,31 @@ public:
     // Returns 1 based amount of expected bytes of statistic data
     uint8_t getExpectedByteCount();
 
-    const byteAssign_t* getAssignmentByChannelField(const ChannelType_t type, const ChannelNum_t channel, const FieldId_t fieldId);
+    const byteAssign_t* getAssignmentByChannelField(const ChannelType_t type, const ChannelNum_t channel, const FieldId_t fieldId) const;
     fieldSettings_t* getSettingByChannelField(const ChannelType_t type, const ChannelNum_t channel, const FieldId_t fieldId);
 
     float getChannelFieldValue(const ChannelType_t type, const ChannelNum_t channel, const FieldId_t fieldId);
     String getChannelFieldValueString(const ChannelType_t type, const ChannelNum_t channel, const FieldId_t fieldId);
-    bool hasChannelFieldValue(const ChannelType_t type, const ChannelNum_t channel, const FieldId_t fieldId);
-    const char* getChannelFieldUnit(const ChannelType_t type, const ChannelNum_t channel, const FieldId_t fieldId);
-    const char* getChannelFieldName(const ChannelType_t type, const ChannelNum_t channel, const FieldId_t fieldId);
-    uint8_t getChannelFieldDigits(const ChannelType_t type, const ChannelNum_t channel, const FieldId_t fieldId);
+    bool hasChannelFieldValue(const ChannelType_t type, const ChannelNum_t channel, const FieldId_t fieldId) const;
+    const char* getChannelFieldUnit(const ChannelType_t type, const ChannelNum_t channel, const FieldId_t fieldId) const;
+    const char* getChannelFieldName(const ChannelType_t type, const ChannelNum_t channel, const FieldId_t fieldId) const;
+    uint8_t getChannelFieldDigits(const ChannelType_t type, const ChannelNum_t channel, const FieldId_t fieldId) const;
 
     bool setChannelFieldValue(const ChannelType_t type, const ChannelNum_t channel, const FieldId_t fieldId, float value);
 
     float getChannelFieldOffset(const ChannelType_t type, const ChannelNum_t channel, const FieldId_t fieldId);
     void setChannelFieldOffset(const ChannelType_t type, const ChannelNum_t channel, const FieldId_t fieldId, const float offset);
 
-    std::list<ChannelType_t> getChannelTypes();
-    const char* getChannelTypeName(const ChannelType_t type);
-    std::list<ChannelNum_t> getChannelsByType(const ChannelType_t type);
+    std::list<ChannelType_t> getChannelTypes() const;
+    const char* getChannelTypeName(const ChannelType_t type) const;
+    std::list<ChannelNum_t> getChannelsByType(const ChannelType_t type) const;
 
-    uint16_t getStringMaxPower(const uint8_t channel);
+    uint16_t getStringMaxPower(const uint8_t channel) const;
     void setStringMaxPower(const uint8_t channel, const uint16_t power);
 
     void resetRxFailureCount();
     void incrementRxFailureCount();
-    uint32_t getRxFailureCount();
+    uint32_t getRxFailureCount() const;
 
     void zeroRuntimeData();
     void zeroDailyData();
@@ -147,10 +147,10 @@ public:
     void setLastUpdate(const uint32_t lastUpdate);
 
     // Update time when internal data structure changes (from inverter and by internal manipulation)
-    uint32_t getLastUpdateFromInternal();
+    uint32_t getLastUpdateFromInternal() const;
     void setLastUpdateFromInternal(const uint32_t lastUpdate);
 
-    bool getYieldDayCorrection();
+    bool getYieldDayCorrection() const;
     void setYieldDayCorrection(const bool enabled);
 private:
     void zeroFields(const FieldId_t* fields);
diff --git a/lib/Hoymiles/src/parser/SystemConfigParaParser.cpp b/lib/Hoymiles/src/parser/SystemConfigParaParser.cpp
index 3ad336b..e866e87 100644
--- a/lib/Hoymiles/src/parser/SystemConfigParaParser.cpp
+++ b/lib/Hoymiles/src/parser/SystemConfigParaParser.cpp
@@ -28,7 +28,7 @@ void SystemConfigParaParser::appendFragment(const uint8_t offset, const uint8_t*
     _payloadLength += len;
 }
 
-float SystemConfigParaParser::getLimitPercent()
+float SystemConfigParaParser::getLimitPercent() const
 {
     HOY_SEMAPHORE_TAKE();
     const float ret = ((((uint16_t)_payload[2]) << 8) | _payload[3]) / 10.0;
@@ -49,12 +49,12 @@ void SystemConfigParaParser::setLastLimitCommandSuccess(const LastCommandSuccess
     _lastLimitCommandSuccess = status;
 }
 
-LastCommandSuccess SystemConfigParaParser::getLastLimitCommandSuccess()
+LastCommandSuccess SystemConfigParaParser::getLastLimitCommandSuccess() const
 {
     return _lastLimitCommandSuccess;
 }
 
-uint32_t SystemConfigParaParser::getLastUpdateCommand()
+uint32_t SystemConfigParaParser::getLastUpdateCommand() const
 {
     return _lastUpdateCommand;
 }
@@ -70,12 +70,12 @@ void SystemConfigParaParser::setLastLimitRequestSuccess(const LastCommandSuccess
     _lastLimitRequestSuccess = status;
 }
 
-LastCommandSuccess SystemConfigParaParser::getLastLimitRequestSuccess()
+LastCommandSuccess SystemConfigParaParser::getLastLimitRequestSuccess() const
 {
     return _lastLimitRequestSuccess;
 }
 
-uint32_t SystemConfigParaParser::getLastUpdateRequest()
+uint32_t SystemConfigParaParser::getLastUpdateRequest() const
 {
     return _lastUpdateRequest;
 }
@@ -86,7 +86,7 @@ void SystemConfigParaParser::setLastUpdateRequest(const uint32_t lastUpdate)
     setLastUpdate(lastUpdate);
 }
 
-uint8_t SystemConfigParaParser::getExpectedByteCount()
+uint8_t SystemConfigParaParser::getExpectedByteCount() const
 {
     return SYSTEM_CONFIG_PARA_SIZE;
 }
diff --git a/lib/Hoymiles/src/parser/SystemConfigParaParser.h b/lib/Hoymiles/src/parser/SystemConfigParaParser.h
index 0237879..847a5d1 100644
--- a/lib/Hoymiles/src/parser/SystemConfigParaParser.h
+++ b/lib/Hoymiles/src/parser/SystemConfigParaParser.h
@@ -10,21 +10,21 @@ public:
     void clearBuffer();
     void appendFragment(const uint8_t offset, const uint8_t* payload, const uint8_t len);
 
-    float getLimitPercent();
+    float getLimitPercent() const;
     void setLimitPercent(const float value);
 
     void setLastLimitCommandSuccess(const LastCommandSuccess status);
-    LastCommandSuccess getLastLimitCommandSuccess();
-    uint32_t getLastUpdateCommand();
+    LastCommandSuccess getLastLimitCommandSuccess() const;
+    uint32_t getLastUpdateCommand() const;
     void setLastUpdateCommand(const uint32_t lastUpdate);
 
     void setLastLimitRequestSuccess(const LastCommandSuccess status);
-    LastCommandSuccess getLastLimitRequestSuccess();
-    uint32_t getLastUpdateRequest();
+    LastCommandSuccess getLastLimitRequestSuccess() const;
+    uint32_t getLastUpdateRequest() const;
     void setLastUpdateRequest(const uint32_t lastUpdate);
 
     // Returns 1 based amount of expected bytes of data
-    uint8_t getExpectedByteCount();
+    uint8_t getExpectedByteCount() const;
 
 private:
     uint8_t _payload[SYSTEM_CONFIG_PARA_SIZE];
diff --git a/lib/TimeoutHelper/TimeoutHelper.cpp b/lib/TimeoutHelper/TimeoutHelper.cpp
index 327075d..3f00c2b 100644
--- a/lib/TimeoutHelper/TimeoutHelper.cpp
+++ b/lib/TimeoutHelper/TimeoutHelper.cpp
@@ -27,7 +27,7 @@ void TimeoutHelper::reset()
     startMillis = millis();
 }
 
-bool TimeoutHelper::occured()
+bool TimeoutHelper::occured() const
 {
     return millis() > (startMillis + timeout);
 }
\ No newline at end of file
diff --git a/lib/TimeoutHelper/TimeoutHelper.h b/lib/TimeoutHelper/TimeoutHelper.h
index 088bc2d..058de09 100644
--- a/lib/TimeoutHelper/TimeoutHelper.h
+++ b/lib/TimeoutHelper/TimeoutHelper.h
@@ -9,7 +9,7 @@ public:
     void set(const uint32_t ms);
     void extend(const uint32_t ms);
     void reset();
-    bool occured();
+    bool occured() const;
 
 private:
     uint32_t startMillis;
diff --git a/src/MqttSettings.cpp b/src/MqttSettings.cpp
index 7ac420c..d5fda2c 100644
--- a/src/MqttSettings.cpp
+++ b/src/MqttSettings.cpp
@@ -175,7 +175,7 @@ bool MqttSettingsClass::getConnected()
     return mqttClient->connected();
 }
 
-String MqttSettingsClass::getPrefix()
+String MqttSettingsClass::getPrefix() const
 {
     return Configuration.get().Mqtt.Topic;
 }
diff --git a/src/NetworkSettings.cpp b/src/NetworkSettings.cpp
index 5bfe08e..1597f41 100644
--- a/src/NetworkSettings.cpp
+++ b/src/NetworkSettings.cpp
@@ -179,7 +179,7 @@ void NetworkSettingsClass::enableAdminMode()
     setupMode();
 }
 
-String NetworkSettingsClass::getApName()
+String NetworkSettingsClass::getApName() const
 {
     return String(ACCESS_POINT_NAME + String(Utils::getChipId()));
 }
@@ -335,7 +335,7 @@ void NetworkSettingsClass::setStaticIp()
     }
 }
 
-IPAddress NetworkSettingsClass::localIP()
+IPAddress NetworkSettingsClass::localIP() const
 {
     switch (_networkMode) {
     case network_mode::Ethernet:
@@ -349,7 +349,7 @@ IPAddress NetworkSettingsClass::localIP()
     }
 }
 
-IPAddress NetworkSettingsClass::subnetMask()
+IPAddress NetworkSettingsClass::subnetMask() const
 {
     switch (_networkMode) {
     case network_mode::Ethernet:
@@ -363,7 +363,7 @@ IPAddress NetworkSettingsClass::subnetMask()
     }
 }
 
-IPAddress NetworkSettingsClass::gatewayIP()
+IPAddress NetworkSettingsClass::gatewayIP() const
 {
     switch (_networkMode) {
     case network_mode::Ethernet:
@@ -377,7 +377,7 @@ IPAddress NetworkSettingsClass::gatewayIP()
     }
 }
 
-IPAddress NetworkSettingsClass::dnsIP(const uint8_t dns_no)
+IPAddress NetworkSettingsClass::dnsIP(const uint8_t dns_no) const
 {
     switch (_networkMode) {
     case network_mode::Ethernet:
@@ -391,7 +391,7 @@ IPAddress NetworkSettingsClass::dnsIP(const uint8_t dns_no)
     }
 }
 
-String NetworkSettingsClass::macAddress()
+String NetworkSettingsClass::macAddress() const
 {
     switch (_networkMode) {
     case network_mode::Ethernet:
@@ -444,12 +444,12 @@ String NetworkSettingsClass::getHostname()
     return resultHostname;
 }
 
-bool NetworkSettingsClass::isConnected()
+bool NetworkSettingsClass::isConnected() const
 {
     return WiFi.localIP()[0] != 0 || ETH.localIP()[0] != 0;
 }
 
-network_mode NetworkSettingsClass::NetworkMode()
+network_mode NetworkSettingsClass::NetworkMode() const
 {
     return _networkMode;
 }
diff --git a/src/PinMapping.cpp b/src/PinMapping.cpp
index 68395b6..8d7062b 100644
--- a/src/PinMapping.cpp
+++ b/src/PinMapping.cpp
@@ -195,7 +195,7 @@ bool PinMappingClass::init(const String& deviceMapping)
     return false;
 }
 
-bool PinMappingClass::isValidNrf24Config()
+bool PinMappingClass::isValidNrf24Config() const
 {
     return _pinMapping.nrf24_clk >= 0
         && _pinMapping.nrf24_cs >= 0
@@ -205,7 +205,7 @@ bool PinMappingClass::isValidNrf24Config()
         && _pinMapping.nrf24_mosi >= 0;
 }
 
-bool PinMappingClass::isValidCmt2300Config()
+bool PinMappingClass::isValidCmt2300Config() const
 {
     return _pinMapping.cmt_clk >= 0
         && _pinMapping.cmt_cs >= 0
@@ -213,7 +213,7 @@ bool PinMappingClass::isValidCmt2300Config()
         && _pinMapping.cmt_sdio >= 0;
 }
 
-bool PinMappingClass::isValidEthConfig()
+bool PinMappingClass::isValidEthConfig() const
 {
     return _pinMapping.eth_enabled;
 }
\ No newline at end of file
diff --git a/src/SunPosition.cpp b/src/SunPosition.cpp
index 3a76687..db14dc5 100644
--- a/src/SunPosition.cpp
+++ b/src/SunPosition.cpp
@@ -29,7 +29,7 @@ void SunPositionClass::loop()
     }
 }
 
-bool SunPositionClass::isDayPeriod()
+bool SunPositionClass::isDayPeriod() const
 {
     if (!_isValidInfo) {
         return true;
@@ -41,7 +41,7 @@ bool SunPositionClass::isDayPeriod()
     return (minutesPastMidnight >= _sunriseMinutes) && (minutesPastMidnight < _sunsetMinutes);
 }
 
-bool SunPositionClass::isSunsetAvailable()
+bool SunPositionClass::isSunsetAvailable() const
 {
     return _isSunsetAvailable;
 }
@@ -51,7 +51,7 @@ void SunPositionClass::setDoRecalc(const bool doRecalc)
     _doRecalc = doRecalc;
 }
 
-bool SunPositionClass::checkRecalcDayChanged()
+bool SunPositionClass::checkRecalcDayChanged() const
 {
     time_t now;
     struct tm timeinfo;
@@ -124,7 +124,7 @@ void SunPositionClass::updateSunData()
     _isValidInfo = true;
 }
 
-bool SunPositionClass::getSunTime(struct tm* info, const uint32_t offset)
+bool SunPositionClass::getSunTime(struct tm* info, const uint32_t offset) const
 {
     // Get today's date
     time_t aTime = time(NULL);
@@ -142,12 +142,12 @@ bool SunPositionClass::getSunTime(struct tm* info, const uint32_t offset)
     return _isValidInfo;
 }
 
-bool SunPositionClass::sunsetTime(struct tm* info)
+bool SunPositionClass::sunsetTime(struct tm* info) const
 {
     return getSunTime(info, _sunsetMinutes);
 }
 
-bool SunPositionClass::sunriseTime(struct tm* info)
+bool SunPositionClass::sunriseTime(struct tm* info) const
 {
     return getSunTime(info, _sunriseMinutes);
 }