Modbus controller text sensor: response_size has no effect

[wowtor]

The problem

Modbus controller text sensor has a response_size attribute, but it seems to be unused. With response_size set to 2 and raw_encode to HEXBYTES, I expect a four character string, but I receive 8 characters, such as "00000000". If appreciated, I don't mind to create a pull request to fix this; see proposed change below.

Which version of ESPHome has the issue?

2023.12.9

What type of installation are you using?

Home Assistant Add-on

Which version of Home Assistant has the issue?

2024.1.6

What platform are you using?

ESP32

Board

esp-wrover-kit

Component causing the issue

modbus controller

Example YAML snippet

text_sensor:
  - platform: modbus_controller
    modbus_controller_id: "omnia_modbus"
    name: "Omnia current HVAC mode"
    id: "omnia_current_hvac_mode"
    register_type: holding
    register_count: 1
    response_size: 2
    address: 101
    entity_category: DIAGNOSTIC
    raw_encode: HEXBYTES
    filters:
      - map:
          - 0000 -> off
          - 0002 -> cool
          - 0003 -> heat

Anything in the logs that might be useful for us?

[09:01:59][D][text_sensor:064]: 'Omnia current HVAC mode': Sending state '00000000'

Additional information

Looking at the source code, it seems that the value for response_size is never used. The relevant snippet seems to be this:

  uint8_t max_items = this->response_bytes;
  uint8_t index = this->offset;
  char buffer[4];
  while ((max_items != 0) && index < data.size()) {
    uint8_t b = data[index];
    switch (this->encode_) {
      case RawEncoding::HEXBYTES:
        sprintf(buffer, "%02x", b);
        output << buffer;
        break;
      case RawEncoding::COMMA:
        sprintf(buffer, index != this->offset ? ",%d" : "%d", b);
        output << buffer;
        break;
      // Anything else no encoding
      case RawEncoding::NONE:
      default:
        output << (char) b;
        break;
    }

    index++;
  }

I expect the value max_items to be decreased, but in fact it never changes. If this is correct, I don't mind to create a pull request, to add a max_items--; at the end of the loop.

[github-actions[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[wowtor]

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