Modbus Controller

The modbus_controller component creates a RS485 connection to control a modbus device

Warning

If you are using the Logger Component uart logging might interfere especially on esp8266. You can disable the uart logging with the baud_rate: 0 option.

../_images/modbus.png

The modbus_controller component uses the modbus component

Hardware setup

I’m using a RS 485 module connected to an ESP32

../_images/rs485.jpg

See [How is this RS485 Module Working?](https://electronics.stackexchange.com/questions/244425/how-is-this-rs485-module-working) on stackexchange for more details

The controller connects to the UART of the MCU. For ESP32 GPIO PIN 16 to TXD PIN 17 to RXD are the default ports but any other pins can be used as well . 3.3V to VCC and GND to GND.

Configuration variables:

  • modbus_id (Optional, ID): Manually specify the ID of the modbus hub.

  • address (Required, ID): The modbus address of the device Specify the modbus device address of the.

  • command_throttle (Optional, int): minimum time in milliseconds between 2 requests to the device. Default is 0ms Because some modbus devices limit the rate of requests the interval between sending requests to the device can be modified.

Getting started with Home Assistant

The following code create a modbus_controller hub talking to a modbus device at address 1 with 115200 bps

Modbus sensors can be directly defined (inline) under the modbus_controller hub or as standalone components Technically there is no difference between the “inline” and the standard definitions approach.

esphome:
  name: solarstation
  platform: ESP32
  board: esp32dev

substitutions:
  updates: 30s

wifi:
  ssid: !secret wifi_sid
  password: !secret wifi_password
  reboot_timeout: 2min

logger:
  level: INFO
  baud_rate: 0

api:
  password: !secret api_password

uart:
  id: mod_bus
  tx_pin: 17
  rx_pin: 16
  baud_rate: 115200
  stop_bits: 1

modbus:
  flow_control_pin: 5
  id: modbus1

modbus_controller:
  - id: epever
    ## the Modbus device addr
    address: 0x1
    modbus_id: modbus1
    setup_priority: -10

text_sensor:
  - name: "rtc_clock"
    platform: modbus_controller
    modbus_controller_id: epever
    id: rtc_clock
    internal: true
    register_type: holding
    address: 0x9013
    register_count: 3
    raw_encode: HEXBYTES
    response_size: 6

switch:
  - platform: modbus_controller
    modbus_controller_id: epever
    id: reset_to_fabric_default
    name: "Reset to Factory Default"
    register_type: coil
    address: 0x15
    bitmask: 1

sensor:
  - platform: modbus_controller
    modbus_controller_id: epever
    name: "Battery Capacity"
    id: battery_capacity
    register_type: holding
    address: 0x9001
    unit_of_measurement: "AH"
    value_type: U_WORD

Protocol decoding example

sensors:
  - platform: modbus_controller
    modbus_controller_id: epever
    id: array_rated_voltage
    name: "array_rated_voltage"
    address: 0x3000
    unit_of_measurement: "V"
    register_type: read
    value_type: U_WORD
    accuracy_decimals: 1
    skip_updates: 60
    filters:
      - multiply: 0.01

  - platform: modbus_controller
    modbus_controller_id: epever
    id: array_rated_current
    name: "array_rated_current"
    address: 0x3001
    unit_of_measurement: "V"
    register_type: read
    value_type: U_WORD
    accuracy_decimals: 2
    filters:
      - multiply: 0.01

  - platform: modbus_controller
    modbus_controller_id: epever
    id: array_rated_power
    name: "array_rated_power"
    address: 0x3002
    unit_of_measurement: "W"
    register_type: read
    value_type: U_DWORD_R
    accuracy_decimals: 1
    filters:
      - multiply: 0.01

  -platform: modbus_controller
    modbus_controller_id: epever
    id: battery_rated_voltage
    name: "battery_rated_voltage"
    address: 0x3004
    unit_of_measurement: "V"
    register_type: read
    value_type: U_WORD
    accuracy_decimals: 1
    filters:
      - multiply: 0.01

  - platform: modbus_controller
    modbus_controller_id: epever
    id: battery_rated_current
    name: "battery_rated_current"
    address: 0x3005
    unit_of_measurement: "A"
    register_type: read
    value_type: U_WORD
    accuracy_decimals: 1
    filters:
      - multiply: 0.01

  - platform: modbus_controller
    modbus_controller_id: epever
    id: battery_rated_power
    name: "battery_rated_power"
    address: 0x3006
    unit_of_measurement: "W"
    register_type: read
    value_type: U_DWORD_R
    accuracy_decimals: 1
    filters:
      - multiply: 0.01

  - platform: modbus_controller
    modbus_controller_id: epever id: charging_mode
    name: "charging_mode"
    address: 0x3008
    unit_of_measurement: ""
    register_type: read
    value_type: U_WORD
    accuracy_decimals: 0

To minimize the required transactions all registers with the same base address are read in one request. The response is mapped to the sensor based on register_count and offset in bytes.

Request

data

description

0x1 (01)

device address

0x4 (04)

function code 4 (Read Input Registers)

0x30 (48)

start address high byte

0x0 (00)

start address low byte

0x0 (00)

number of registers to read high byte

0x9 (09)

number of registers to read low byte

0x3f (63)

crc

0xc (12)

crc

Response

offset

data

value (type)

description

H

0x1 (01)

device address

H

0x4 (04)

function code

H

0x12 (18)

byte count

0

0x27 (39)

U_WORD

array_rated_voltage high byte

1

0x10 (16)

0x2710 (100000)

array_rated_voltage low byte

2

0x7 (7)

U_WORD

array_rated_current high byte

3

0xd0 (208)

0x7d0 (2000)

array_rated_current low byte

4

0xcb (203)

U_DWORD_R

array_rated_power high byte of low word

5

0x20 (32)

spans 2 register

array_rated_power low byte of low word

6

0x0 (0)

array_rated_power high byte of high word

7

0x0 (0)

0x0000CB20 (52000)

array_rated_power low byte of high word

8

0x9 (09)

U_WORD

battery_rated_voltage high byte

9

0x60 (96)

0x960 (2400)

battery_rated_voltage low byte

10

0x7 (07)

U_WORD

battery_rated_current high word

11

0xd0 (208)

0x7d0 (2000)

battery_rated_current high word

12

0xcb (203)

U_DWORD_R

battery_rated_power high byte of low word

13

0x20 (32)

spans 2 register

battery_rated_power low byte of low word

14

0x0 (0)

battery_rated_power high byte of high word

15

0x0 (0)

0x0000CB20 (52000)

battery_rated_power low byte of high word

16

0x0 (0)

U_WORD

charging_mode high byte

17

0x2 (02)

0x2 (MPPT)

charging_mode low byte

C

0x2f (47)

crc

C

0x31 (49)

crc

Note

Write support is only implemented for switches. However the C++ code provides the required API to write to a modbus device.

These methods can be called from a lambda.

Here is an example how to set config values to for an EPEVER Trace AN controller. The code synchronizes the localtime of MCU to the epever controller The time is set by writing 12 bytes to register 0x9013. Then battery charge settings are sent.

esphome:
  name: solarstation-test
  platform: ESP32
  board: esp32dev

  ## send config values at startup
  ## configure rtc clock and battery charge settings
  on_boot:
    priority: -100
    then:
      - lambda: |-

on_boot:
  ## configure controller settings at setup
  ## make sure priority is lower than setup_priority of modbus_controller
  priority: -100
  then:
    - lambda: |-
        // get local time and sync to controller
        time_t now = ::time(nullptr);
        struct tm *time_info = ::localtime(&now);
        int seconds = time_info->tm_sec;
        int minutes = time_info->tm_min;
        int hour = time_info->tm_hour;
        int day = time_info->tm_mday;
        int month = time_info->tm_mon + 1;
        int year = time_info->tm_year % 100;
        esphome::modbus_controller::ModbusController *controller = id(epever);
        // if there is no internet connection localtime returns year 70
        if (year != 70) {
          // create the payload
          std::vector<uint16_t> rtc_data = {uint16_t((minutes << 8) | seconds), uint16_t((day << 8) | hour),
                                            uint16_t((year << 8) | month)};
          // Create a modbus command item with the time information as the payload
          esphome::modbus_controller::ModbusCommandItem set_rtc_command =
              esphome::modbus_controller::ModbusCommandItem::create_write_multiple_command(controller, 0x9013, 3, rtc_data);
          // Submit the command to the send queue
          epever->queue_command(set_rtc_command);
          ESP_LOGI("ModbusLambda", "EPSOLAR RTC set to %02d:%02d:%02d %02d.%02d.%04d", hour, minutes, seconds, day, month,
                  year + 2000);
        }
        // Battery settings
        // Note: these values are examples only and apply my AGM Battery
        std::vector<uint16_t> battery_settings1 = {
            0,       // 9000 Battery Type 0 =  User
            0x0073,  // 9001 Battery Cap 0x55 == 115AH
            0x012C,  // 9002 Temp compensation -3V /°C/2V
            0x05DC,  // 9003 0x5DC == 1500 Over Voltage Disconnect Voltage 15,0
            0x058C,  // 9004 0x58C == 1480 Charging Limit Voltage 14,8
            0x058C,  // 9005 Over Voltage Reconnect Voltage 14,8
            0x05BF,  // 9006 Equalize Charging Voltage 14,6
            0x05BE,  // 9007 Boost Charging Voltage 14,7
            0x0550,  // 9008 Float Charging Voltage 13,6
            0x0528,   // 9009 Boost Reconnect Charging Voltage 13,2
            0x04C4,  // 900A Low Voltage Reconnect Voltage 12,2
            0x04B0,  // 900B Under Voltage Warning Reconnect Voltage 12,0
            0x04BA,  // 900c Under Volt. Warning Volt 12,1
            0x04BA,  // 900d Low Volt. Disconnect Volt. 11.8
            0x04BA   // 900E Discharging Limit Voltage 11.8
        };

        // Boost and equalization periods
        std::vector<uint16_t> battery_settings2 = {
            0x0000,  // 906B Equalize Duration (min.) 0
            0x0075   // 906C Boost Duration (aka absorb) 117 mins
        };
        esphome::modbus_controller::ModbusCommandItem set_battery1_command =
            esphome::modbus_controller::ModbusCommandItem::create_write_multiple_command(controller, 0x9000, battery_settings1.size() ,
                                                                                        battery_settings1);

        esphome::modbus_controller::ModbusCommandItem set_battery2_command =
            esphome::modbus_controller::ModbusCommandItem::create_write_multiple_command(controller, 0x906B, battery_settings3.size(),
                                                                                        battery_settings2);
        delay(200) ;
        controller->queue_command(set_battery1_command);
        delay(200) ;
        controller->queue_command(set_battery2_command);
        ESP_LOGI("ModbusLambda", "EPSOLAR Battery set");



uart:
  id: mod_bus
  tx_pin: 19
  rx_pin: 18
  baud_rate: 115200
  stop_bits: 1

modbus:
  #flow_control_pin: 23
  send_wait_time: 200ms
  id: mod_bus_epever

modbus_controller:
  - id: epever
    ## the Modbus device addr
    address: 0x1
    modbus_id: mod_bus_epever
    command_throttle: 0ms
    setup_priority: -10
    update_interval: ${updates}

sensor:
  - platform: modbus_controller
    modbus_controller_id: epever
    id: array_rated_voltage
    name: "array_rated_voltage"
    address: 0x3000
    unit_of_measurement: "V"
    register_type: read
    value_type: U_WORD
    accuracy_decimals: 1
    filters:
      - multiply: 0.01

  - platform: modbus_controller
    modbus_controller_id: epever
    id: array_rated_current
    name: "array_rated_current"
    address: 0x3001
    unit_of_measurement: "A"
    register_type: read
    value_type: U_WORD
    accuracy_decimals: 2
    filters:
      - multiply: 0.01

  - platform: modbus_controller
    modbus_controller_id: epever
    id: array_rated_power
    name: "array_rated_power"
    address: 0x3002
    unit_of_measurement: "W"
    register_type: read
    value_type: U_DWORD_R
    accuracy_decimals: 1
    filters:
      - multiply: 0.01

See Also