Reading register from Siemens LOGO! PLC via ModBus

Hi, I’m trying to read one of the analog inputs from my PLC

Does anyone what to put into the config-file to be able to read the “AI” inputs?


anything that will help me will be much appreciated.

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Hello @fesklord,

I have a LOGO where input registers are temperatures, they are short integer so if I read 321 it means 32.1°C.

I divide my configuration.yaml so I have to edit 3 files:

  • configuration.yaml:

    modbus: !include modbus.yaml
    template: !include templates.yaml
  • modbus.yaml (please note the host is your LOGO IP address, I store mine in the secrets.yaml file):

    - name: "Siemens LOGO"
      type: tcp
      host: !sercret siemens_logo_ip
      port: 502
        - name: "MyLOGO1"
          unique_id: mylogo1
          input_type: input
          slave: 1
          address: 0
          count: 8
          data_type: custom
          structure: ">8h"

    Note: structure:">8h" means I have reading 8 short number of 2 bytes each with big endian ending. You can read about Python structure here.

  • As I read all 8 input registers at once and then use a template to separate the values, then I have less modbus requests made to the LOGO. So I divide the values in templates.yaml:

    - name: Heater temperature
      state: "{{ states('sensor.mylogo1').split(',')[0] | multiply(0.1) }}"
      state_class: measurement
      unit_of_measurement: °C
    - name: External temperature
      state: "{{ states('sensor.mylogo1').split(',')[1] | multiply(0.1) }}"
      state_class: measurement
      unit_of_measurement: °C
    # and so on until states('sensor.mylogo1').split(',')[7]

I hope that helps and do not hesitate to reach out if you have any question.

@cloom, thank you!

1 Like