ESPHome modbus not functional - Printable Version

ESPHome modbus not functional - Printable Version

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+--- Thread: ESPHome modbus not functional (/showthread.php?tid=9804)

ESPHome modbus not functional - Bergoglio - 09-06-2026

Hello, we recently bought and set up the KC868-A8S with a Midea heat pump. ESPHome was used to set up the switches, binary sensors and modbus. The first two work as intended, while the modbus seemingly not being able to read or send requests properly.

Here is the chunk of the code that relates to and might influence the modbus and one of the sensors:

Code:
esphome:

  name: centralina-freddo

  friendly_name: Centralina freddo

esp32:

  variant: ESP32

  flash_size: 4MB

  board: esp32dev

logger:

api:

  encryption:

    key: [cencored for privacy]

ota:

  - platform: esphome

    password: [cencored for privacy]

i2c:

  - id: bus_a

    sda: GPIO4

    scl: GPIO5

    scan: true

ethernet:

  type: LAN8720

  clk:

    pin: GPIO17

    mode: CLK_OUT

  mdc_pin: GPIO23

  mdio_pin: GPIO18

  phy_addr: 0

uart:

  - id: uart_1

    tx_pin: GPIO33

    rx_pin: GPIO32

    baud_rate: 9600

    stop_bits: 1

    parity: NONE

    data_bits: 8

    rx_full_threshold: 8B

    debug:

      direction: BOTH

modbus:

  - id: modbus_1

    uart_id: uart_1

    role: client

modbus_controller:

  - id: modbus_controller_1

    address: 0x01

    modbus_id: modbus_1

    setup_priority: -10

    update_interval: 15s

sensor:

  - platform: modbus_controller

    name: "Temp. Esterna (PdC)"

    id: pdc_esterna_TP

    modbus_controller_id: modbus_controller_1

    address: 107

    register_type: holding

    unit_of_measurement: °C

    device_class: temperature

    state_class: measurement

    value_type: S_WORD

    accuracy_decimals: 1

Attempted fixes (that did not work):

phisically inverting the A and B connections
changing the modbus controller adress
changing the sensor adress to hexadecimal
changing the register type
changing the value type
adding accuracy decimals
changing th esp variant from inf to dev
changing the api to be more generic
inverting the tx and rx pins
changing the parity to even and odd
changing the amount of data bits
changing the amount of rx_full_threshold
removing the client role
removing the uart id
changing the update interval
decreasing the turnaround time to 50ms

At the moment, with this code, the log output repeats these lines:

Quote:[19:49:26.943][W][modbus:1214]: Clearing buffer of 21 bytes - timeout after partial response 1188899ms after last send
[19:49:26.954][D][uart_debug:113]: <<< 7E:66:66:00:66:F8:FE:18:E6:FE:E6:F8:FE:FE:E6:06:FE:E6:F8:FE:FE

Quote:[19:50:11.845][D][modbus:1118]: Frame already active for 1 with 2 requests pending, refused
[19:50:11.847][D][modbus_controller:204]: Poll refused by hub for range 0x68

We are unsure of what to do, and I am out of ideas on how to fix this.
All the GPIOs are correct. They have been checked.

Any help would be appreciated,
Thank you

RE: ESPHome modbus not functional - admin - 09-06-2026

just config esphome yaml according to sensor's protocol.