Make energy readings optional (#91)

README.md

@@ -203,8 +203,8 @@ Meters provide data about power and energy consumption. Available meter implemen
     model: sdm
     uri: rs485.fritz.box:23
     id: 2
-    power: PowerL1
-    energy: Export
+    power: Power # reading as understood by MBMD, leave empty for power default value
+    energy: Export # optional reading for total energy values, specify for charge meter
   ```
 
 - `sma`: SMA Home Manager and SMA Energy Meter. Power reading is configured out of the box but can be customizied if necessary. To obtain energy readings define the desired Obis code (Import Energy: "1:1.8.0", Export Energy: "1:2.8.0"):
@@ -214,7 +214,7 @@ Meters provide data about power and energy consumption. Available meter implemen
     type: sdm
     uri: 192.168.1.4
     power: # leave empty for mixed import/export energy
-    energy: # leave empty to disable or chose obis 1:1.8.0/1:2.8.0
+    energy: # leave empty to disable or choose obis 1:1.8.0/1:2.8.0
   ```
 
 - `default`: default meter implementation where meter readings- `power` and `energy` are configured using [plugin](#plugins)

meter/modbus.go

@@ -81,24 +81,24 @@ func NewModbusFromConfig(log *util.Logger, other map[string]interface{}) api.Met
 		}
 	}
 
-	// energy reading
-	if cc.Energy == "" {
-		cc.Energy = "Sum"
-	}
-
-	energyM, err := meters.MeasurementString(cc.Energy)
-	if err != nil {
-		log.FATAL.Fatalf("invalid measurement for energy: %s", cc.Energy)
-	}
-
-	// for RS485 check if producer supports the measurement
-	m.opEnergy = rs485.Operation{IEC61850: energyM}
-	if dev, ok := device.(*rs485.RS485); ok {
-		m.opEnergy = modbus.RS485FindDeviceOp(dev, energyM)
-
-		if m.opEnergy.IEC61850 == 0 {
-			log.FATAL.Fatalf("unsupported measurement for energy: %s", cc.Energy)
+	// decorate energy reading
+	if cc.Energy != "" {
+		energyM, err := meters.MeasurementString(cc.Energy)
+		if err != nil {
+			log.FATAL.Fatalf("invalid measurement for energy: %s", cc.Energy)
 		}
+
+		// for RS485 check if producer supports the measurement
+		m.opEnergy = rs485.Operation{IEC61850: energyM}
+		if dev, ok := device.(*rs485.RS485); ok {
+			m.opEnergy = modbus.RS485FindDeviceOp(dev, energyM)
+
+			if m.opEnergy.IEC61850 == 0 {
+				log.FATAL.Fatalf("unsupported measurement for energy: %s", cc.Energy)
+			}
+		}
+
+		return &ModbusEnergy{m}
 	}
 
 	return m
@@ -131,7 +131,12 @@ func (m *Modbus) CurrentPower() (float64, error) {
 	return m.floatGetter(m.opPower)
 }
 
+// ModbusEnergy decorates Modbus with api.MeterEnergy interface
+type ModbusEnergy struct {
+	*Modbus
+}
+
 // TotalEnergy implements the Meter.TotalEnergy interface
-func (m *Modbus) TotalEnergy() (float64, error) {
+func (m *ModbusEnergy) TotalEnergy() (float64, error) {
 	return m.floatGetter(m.opEnergy)
 }

provider/modbus.go

@@ -19,6 +19,7 @@ type Modbus struct {
 	op      rs485.Operation
 }
 
+// ModbusSettings combine physical modbus configuration and MBMD model
 type ModbusSettings struct {
 	Model             string
 	modbus.Connection `mapstructure:",squash"`
@@ -49,7 +50,7 @@ func NewModbusFromConfig(log *util.Logger, typ string, other map[string]interfac
 		conn.Slave(cc.ID)
 		err = device.Initialize(conn.ModbusClient())
 
-		// silence Kostal implementation errors
+		// silence KOSTAL implementation errors
 		if _, partial := err.(meters.SunSpecPartiallyInitialized); partial {
 			err = nil
 		}