ESPHome config for Dingtian 4CH Relay (dtwonder DT-R004) + Modbus NPN IO extender module

dingtian-4ch.yaml

esphome:
  name: dingtian-4ch
  friendly_name: Dingtian 4CH
  comment: "ESP32-D0WD v1.0"
  # Change NPN module modbus speed to 19200
  # Baud rate corresponds to the number: 0: 1200  1: 2400  2: 4800  3: 9600  4: 19200
  #on_boot:
  #  ## configure controller settings at setup
  #  ## make sure priority is lower than setup_priority of modbus_controller
  #  priority: -100
  #  then:
  #    - lambda: |-
  #        esphome::modbus_controller::ModbusController *controller = id(npn);
  #        esphome::modbus_controller::ModbusCommandItem cmd = esphome::modbus_controller::ModbusCommandItem::create_write_single_command(
  #          controller, 0x00FF, 0x0004);
  #        delay(200);
  #        controller->queue_command(cmd);
  #        ESP_LOGI("ModbusLambda", "New address set");

esp32:
  board: esp32dev
  framework:
    type: esp-idf

# Enable logging
logger:

# Enable Home Assistant API
api:
  encryption:
    key: !secret encryption_key

ota:
  password: !secret ota_password

#wifi:
#  ssid: !secret wifi_ssid
#  password: !secret wifi_password

ethernet:
  type: JL1101
  mdc_pin: GPIO23
  mdio_pin: GPIO18
  phy_addr: 0
  clk_mode: GPIO17_OUT
  power_pin: GPIO0

uart:
  id: mod_bus
  tx_pin: 1
  rx_pin: 3
  baud_rate: 19200
  stop_bits: 1
  parity: NONE
  data_bits: 8
  debug:
    direction: BOTH

modbus:
  flow_control_pin: 13
  id: modbus1

modbus_controller:
  - id: npn
    address: 0x1
    modbus_id: modbus1
    setup_priority: -10
    update_interval: 500ms

status_led:
  pin:
    number: GPIO15
    inverted: true

sensor:
  - platform: modbus_controller
    modbus_controller_id: npn
    id: io_range_1
    name: "IO Range 1"
    address: 0x00C0
    register_type: holding
    value_type: U_WORD
    internal: true
  - platform: modbus_controller
    modbus_controller_id: npn
    id: io_range_2
    name: "IO Range 2"
    address: 0x00C1
    register_type: holding
    value_type: U_WORD
    internal: true

binary_sensor:
  - platform: gpio
    name: "Factory Button"
    internal: true
    pin:
      number: GPIO34
      inverted: true
    on_press:
      then:
        - switch.toggle: restart_switch

  - name: "Main Input 1"
    id: m_io_1
    platform: gpio
    pin:
      number: GPIO36
      inverted: true
  - name: "Main Input 2"
    id: m_io_2
    platform: gpio
    pin:
      number: GPIO39
      inverted: true
  - name: "Main Input 3"
    id: m_io_3
    platform: gpio
    pin:
      number: GPIO33
      inverted: true
  - name: "Main Input 4"
    id: m_io_4
    platform: gpio
    pin:
      number: GPIO35
      inverted: true

  # Modbus NPN module inputs
  # Range 1
  - platform: template
    id: io_01
    name: "Input 01"
    lambda: |-
      return ((int(id(io_range_1).state) >> 0) & 1);
  - platform: template
    id: io_02
    name: "Input 02"
    lambda: |-
      return ((int(id(io_range_1).state) >> 1) & 1);
  - platform: template
    id: io_03
    name: "Input 03"
    lambda: |-
      return ((int(id(io_range_1).state) >> 2) & 1);
  - platform: template
    id: io_04
    name: "Input 04"
    lambda: |-
      return ((int(id(io_range_1).state) >> 3) & 1);
  - platform: template
    id: io_05
    name: "Input 05"
    lambda: |-
      return ((int(id(io_range_1).state) >> 4) & 1);
  - platform: template
    id: io_06
    name: "Input 06"
    lambda: |-
      return ((int(id(io_range_1).state) >> 5) & 1);
  - platform: template
    id: io_07
    name: "Input 07"
    lambda: |-
      return ((int(id(io_range_1).state) >> 6) & 1);
  - platform: template
    id: io_08
    name: "Input 08"
    lambda: |-
      return ((int(id(io_range_1).state) >> 7) & 1);
  - platform: template
    id: io_09
    name: "Input 09"
    lambda: |-
      return ((int(id(io_range_1).state) >> 8) & 1);
  - platform: template
    id: io_10
    name: "Input 10"
    lambda: |-
      return ((int(id(io_range_1).state) >> 9) & 1);
  - platform: template
    id: io_11
    name: "Input 11"
    lambda: |-
      return ((int(id(io_range_1).state) >> 10) & 1);
  - platform: template
    id: io_12
    name: "Input 12"
    lambda: |-
      return ((int(id(io_range_1).state) >> 11) & 1);
  - platform: template
    id: io_13
    name: "Input 13"
    lambda: |-
      return ((int(id(io_range_1).state) >> 12) & 1);
  - platform: template
    id: io_14
    name: "Input 14"
    lambda: |-
      return ((int(id(io_range_1).state) >> 13) & 1);
  - platform: template
    id: io_15
    name: "Input 15"
    lambda: |-
      return ((int(id(io_range_1).state) >> 14) & 1);
  - platform: template
    id: io_16
    name: "Input 16"
    lambda: |-
      return ((int(id(io_range_1).state) >> 15) & 1);
  # Range 2
  - platform: template
    id: io_17
    name: "Input 17"
    lambda: |-
      return ((int(id(io_range_2).state) >> 0) & 1);
  - platform: template
    id: io_18
    name: "Input 18"
    lambda: |-
      return ((int(id(io_range_2).state) >> 1) & 1);
  - platform: template
    id: io_19
    name: "Input 19"
    lambda: |-
      return ((int(id(io_range_2).state) >> 2) & 1);
  - platform: template
    id: io_20
    name: "Input 20"
    lambda: |-
      return ((int(id(io_range_2).state) >> 3) & 1);
  - platform: template
    id: io_21
    name: "Input 21"
    lambda: |-
      return ((int(id(io_range_2).state) >> 4) & 1);
  - platform: template
    id: io_22
    name: "Input 22"
    lambda: |-
      return ((int(id(io_range_2).state) >> 5) & 1);
  - platform: template
    id: io_23
    name: "Input 23"
    lambda: |-
      return ((int(id(io_range_2).state) >> 6) & 1);
  - platform: template
    id: io_24
    name: "Input 24"
    lambda: |-
      return ((int(id(io_range_2).state) >> 7) & 1);
  - platform: template
    id: io_25
    name: "Input 25"
    lambda: |-
      return ((int(id(io_range_2).state) >> 8) & 1);
  - platform: template
    id: io_26
    name: "Input 26"
    lambda: |-
      return ((int(id(io_range_2).state) >> 9) & 1);
  - platform: template
    id: io_27
    name: "Input 27"
    lambda: |-
      return ((int(id(io_range_2).state) >> 10) & 1);
  - platform: template
    id: io_28
    name: "Input 28"
    lambda: |-
      return ((int(id(io_range_2).state) >> 11) & 1);
  - platform: template
    id: io_29
    name: "Input 29"
    lambda: |-
      return ((int(id(io_range_2).state) >> 12) & 1);
  - platform: template
    id: io_30
    name: "Input 30"
    lambda: |-
      return ((int(id(io_range_2).state) >> 13) & 1);
  - platform: template
    id: io_31
    name: "Input 31"
    lambda: |-
      return ((int(id(io_range_2).state) >> 14) & 1);
  - platform: template
    id: io_32
    name: "Input 32"
    lambda: |-
      return ((int(id(io_range_2).state) >> 15) & 1);

switch:
  - name: "Relay 4"
    platform: gpio
    pin: GPIO12
  - name: "Relay 3"
    platform: gpio
    pin: GPIO32
  - name: "Relay 2"
    platform: gpio
    pin: GPIO2
  - name: "Relay 1"
    platform: gpio
    pin: GPIO16
  
  - platform: restart
    name: "Restart"
    internal: true
    id: restart_switch

I tried to flash my 4-ch board, but there seems a secure boot fuse to be set, and it's not possible to erase the device.

How did you flash the esp32?

They send it locked by default, but if you will add a comment to the order to send you a version with test firmware for your own flashing, then it will be ok.
I fell into this trap as well for the first time :(
The only way I found is to solder a new, clean ESP module if you don't want to order a new one.

ok, found this answer on serveral other locations now. Well I do have some blank ESP32 laying arround. So I need to swap...