switch:
  - platform: modbus_controller
    modbus_controller_id: ${cid}
    name: ${name}
    register_type: holding
    address: ${dev_addr}
    write_lambda: |-
      bool open = (x == 1);
      payload.push_back(${dev_addr});  // device address
      payload.push_back(0x6);  // write function
      payload.push_back(0); // relay select
      payload.push_back(${register_addr});  // 
      payload.push_back(open ? 0x01 : 0x02); // Command
      payload.push_back(0x00);
      return true;