perf(PowerMeter): query PowerMeter on demand

In addition to the cyclic query of the power meters, they will be queried on demand when total power is requested and last update is older than 1 second.

include/PowerMeter.h

@@ -60,6 +60,8 @@ private:
 
     bool mqttInitDone = false;
 
+    void readPowerMeter();
+
     bool smlReadLoop();
     const std::list<OBISHandler> smlHandlerList{
         {{0x01, 0x00, 0x10, 0x07, 0x00, 0xff}, &smlOBISW, &_powerMeter1Power},

src/PowerMeter.cpp

@@ -96,6 +96,11 @@ void PowerMeterClass::onMqttMessage(const espMqttClientTypes::MessageProperties&
 
 float PowerMeterClass::getPowerTotal()
 {
+    CONFIG_T& config = Configuration.get();
+    if (!config.PowerMeter_Enabled
+            || (millis() - _lastPowerMeterUpdate) < (1000)) {
+        readPowerMeter();
+    }
     return _powerMeter1Power + _powerMeter2Power + _powerMeter3Power;
 }
 
@@ -137,6 +142,19 @@ void PowerMeterClass::loop()
         return;
     }
 
+    readPowerMeter();
+
+    MessageOutput.printf("PowerMeterClass: TotalPower: %5.2f\r\n", getPowerTotal());
+
+    mqtt();
+
+    _lastPowerMeterCheck = millis();
+}
+
+void PowerMeterClass::readPowerMeter()
+{
+    CONFIG_T& config = Configuration.get();
+    
     uint8_t _address = config.PowerMeter_SdmAddress;
 
     if (config.PowerMeter_Source == SOURCE_SDM1PH) {
@@ -169,12 +187,6 @@ void PowerMeterClass::loop()
             _lastPowerMeterUpdate = millis();
         }
     }
-
-    MessageOutput.printf("PowerMeterClass: TotalPower: %5.2f\r\n", getPowerTotal());
-
-    mqtt();
-
-    _lastPowerMeterCheck = millis();
 }
 
 bool PowerMeterClass::smlReadLoop()