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P1 Smart Meter~

Reading serial data from a P1 smart meter using a Wemos with Tasmota installed.

Tested on the following smart meters:

  • Kaifa MA105C
  • De Landis + Gyr, E350 (ZCF110)
  • Sanxing SX631 (S34U18)

Schematics~

The transistor makes sure that the RxD signal is converted and inverted to 3.3V. According to the DSMR v5.0.2 P1 specification the P1 connector on the meter provides 5V DC output for the OSM (Other Service Module) connected to this port, which is able to continuously supply maximum current of 250mA. A Wemos D1 mini module draws way less than 100mA so it is perfectly safe to use this as a power source. It can be powered through the 5V pin just inserting a protection diode.

Tasmota Settings~

In the Configuration -> Configure Module page, select module Generic (18)

From the web console set the serial delimiter to 10 (newline). This makes Tasmota publish each line of the telegram separately to mqtt.

  • SerialDelimiter 10
  • SerialSend 1

For more details see serial-bridge.

Should you run into problems with serial buffer overflows, then try to increase the serial buffer size using SerialBuffer 520. This will not be automatically persisted, so try the command first and when the device works fine after having increased the serial buffer size, then try to add a rule like:

Rule1 ON Power1#Boot DO SerialBuffer 520 ENDON

Example output~

Below an example of the telegram message published (per line) to mqtt. From here your HA system can process the data required for your needs.

09:16:17 MQT: tele/wemos-9/RESULT = {"SerialReceived":"/KFM5KAIFA-METER\r"}
09:16:17 MQT: tele/wemos-9/RESULT = {"SerialReceived":"\r"}
09:16:17 MQT: tele/wemos-9/RESULT = {"SerialReceived":"1-3:0.2.8(42)\r"}
09:16:17 MQT: tele/wemos-9/RESULT = {"SerialReceived":"0-0:1.0.0(200913101618S)\r"}
09:16:17 MQT: tele/wemos-9/RESULT = {"SerialReceived":"0-0:96.1.1(4530303235303030303639363432393136)\r"}
09:16:17 MQT: tele/wemos-9/RESULT = {"SerialReceived":"1-0:1.8.1(005779.835*kWh)\r"}
09:16:17 MQT: tele/wemos-9/RESULT = {"SerialReceived":"1-0:1.8.2(005583.617*kWh)\r"}
09:16:17 MQT: tele/wemos-9/RESULT = {"SerialReceived":"1-0:2.8.1(000000.000*kWh)\r"}
09:16:17 MQT: tele/wemos-9/RESULT = {"SerialReceived":"1-0:2.8.2(000000.000*kWh)\r"}
09:16:17 MQT: tele/wemos-9/RESULT = {"SerialReceived":"0-0:96.14.0(0001)\r"}
09:16:17 MQT: tele/wemos-9/RESULT = {"SerialReceived":"1-0:1.7.0(00.498*kW)\r"}
09:16:17 MQT: tele/wemos-9/RESULT = {"SerialReceived":"1-0:2.7.0(00.000*kW)\r"}
09:16:17 MQT: tele/wemos-9/RESULT = {"SerialReceived":"0-0:96.7.21(00000)\r"}
09:16:17 MQT: tele/wemos-9/RESULT = {"SerialReceived":"0-0:96.7.9(00000)\r"}
09:16:17 MQT: tele/wemos-9/RESULT = {"SerialReceived":"1-0:99.97.0(1)(0-0:96.7.19)(000101000001W)(2147483647*s)\r"}
09:16:17 MQT: tele/wemos-9/RESULT = {"SerialReceived":"1-0:32.32.0(00000)\r"}
09:16:17 MQT: tele/wemos-9/RESULT = {"SerialReceived":"1-0:32.36.0(00000)\r"}
09:16:17 MQT: tele/wemos-9/RESULT = {"SerialReceived":"0-0:96.13.1()\r"}
09:16:17 MQT: tele/wemos-9/RESULT = {"SerialReceived":"0-0:96.13.0()\r"}
09:16:17 MQT: tele/wemos-9/RESULT = {"SerialReceived":"1-0:31.7.0(002*A)\r"}
09:16:17 MQT: tele/wemos-9/RESULT = {"SerialReceived":"1-0:21.7.0(00.496*kW)\r"}
09:16:17 MQT: tele/wemos-9/RESULT = {"SerialReceived":"1-0:22.7.0(00.000*kW)\r"}
09:16:17 MQT: tele/wemos-9/RESULT = {"SerialReceived":"0-1:24.1.0(003)\r"}
09:16:17 MQT: tele/wemos-9/RESULT = {"SerialReceived":"0-1:96.1.0(4730303332353631323736373836373136)\r"}
09:16:17 MQT: tele/wemos-9/RESULT = {"SerialReceived":"0-1:24.2.1(200913100000S)(04139.079*m3)\r"}
09:16:17 MQT: tele/wemos-9/RESULT = {"SerialReceived":"!F798\r"}

Description of each line~

see also DSMR 5.0 - P1 Companion Standard

Header information - {"SerialReceived":"/KFM5KAIFA-METER"}
Empty line - {"SerialReceived":""}
Version information for P1 output - {"SerialReceived":"1-3:0.2.8(42)"}
Date-time stamp of the P1 message - {"SerialReceived":"0-0:1.0.0(181227093413W)"}
Equipment identifier - {"SerialReceived":"0-0:96.1.1(4530303235303030303639363432393136)"}
electricityUsedTariff1 >> Meter Reading electricity delivered to client (Tariff 1) in 0,001 kWh - {"SerialReceived":"1-0:1.8.1(002293.192*kWh)"}
electricityUsedTariff2 >> Meter Reading electricity delivered to client (Tariff 2) in 0,001 kWh - {"SerialReceived":"1-0:1.8.2(002523.640*kWh)"}
Meter Reading electricity delivered by client (Tariff 1) in 0,001 kWh - {"SerialReceived":"1-0:2.8.1(000000.000*kWh)"}
Meter Reading electricity delivered by client (Tariff 2) in 0,001 kWh - {"SerialReceived":"1-0:2.8.2(000000.000*kWh)"}
electricityActiveTariff >> Tariff indicator electricity. The tariff indicator can also be used to switch tariff dependent loads e.g boilers. This is the responsibility of the P1 user - {"SerialReceived":"0-0:96.14.0(0002)"}
Actual electricity power delivered (+P) in 1 Watt resolution - {"SerialReceived":"1-0:1.7.0(00.474*kW)"}
Actual electricity power received (-P) in 1 Watt resolution - {"SerialReceived":"1-0:2.7.0(00.000*kW)"}
Number of power failures in any phase - {"SerialReceived":"0-0:96.7.21(00000)"}
Number of long power failures in any phase - {"SerialReceived":"0-0:96.7.9(00000)"}
Power Failure Event Log (long power failures) - {"SerialReceived":"1-0:99.97.0(1)(0-0:96.7.19)(000101000001W)(2147483647*s)"}
Number of voltage sags in phase L1 - {"SerialReceived":"1-0:32.32.0(00000)"}
Number of voltage swells in phase L1 - {"SerialReceived":"1-0:32.36.0(00000)"}
Text message max 1024 characters. - {"SerialReceived":"0-0:96.13.1()"}
Text message max 1024 characters. - {"SerialReceived":"0-0:96.13.0()"}
Instantaneous current L1 in A resolution - {"SerialReceived":"1-0:31.7.0(002*A)"}
Instantaneous active power L1 (+P) in W resolution - {"SerialReceived":"1-0:21.7.0(00.474*kW)"}
Instantaneous active power L1 (-P) in W resolution - {"SerialReceived":"1-0:22.7.0(00.000*kW)"}
Device-Type - {"SerialReceived":"0-1:24.1.0(003)"}
Equipment identifier (Gas) - {"SerialReceived":"0-1:96.1.0(4730303332353631323736373836373136)"}
GasMeterReadingFiveMinutes >> Last 5-minute value (temperature converted), gas delivered to client in m3, including decimal values and capture time - {"SerialReceived":"0-1:24.2.1(181227090000W)(02910.491*m3)"}
{"SerialReceived":"!5E3E"}
Also see Tasmota's Smart Meter Interface if you want to have these OBIS lines translated in selected sensors populatinng MQTT payloads.

Additional info * Kaifa Meters (Dutch) * DSMR 5.0 - P1 Companion Standard

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