Water level sensor QDY30A modbus RS485 with ESP32 S2 mini

ESPHome
7

You were right with a flow control pin. I definitely need to write something to sensor - commands for reading. So I need a flow control pin for MAX485.

Finally my wiring:

2024-03-03 tank sensor wiring2.drawio
2024-03-03 tank sensor wiring2.drawio1920×860 86.3 KB

I have also switched the A and B (blue and yellow) wires from sensor to MAX485. Now it is working. Sensor is sending unit “cm”, but is measuring in “mm”. Measurements are very quick and very accurate (water level in the bucket 122mm, value returned: 122). Current draw by sensor is stable 5.7mA.

My final esphome yaml for those, who will look for working setup in a future:

substitutions:
  devicename: water-tank
  friendly_name: Water tank sensor
  device_description:  Water tank sensor (Carat 4m3)

esphome:
  name: ${devicename}
  friendly_name: ${friendly_name}
  comment: ${device_description}

esp32:
  board: lolin_s2_mini #Pinout: https://www.wemos.cc/en/latest/s2/s2_mini.html
  variant: esp32s2
  framework:
    type: arduino

wifi:
  networks:
  - ssid: !secret wifi_ssid
    password: !secret wifi_password
  # Enable fallback hotspot (captive portal) in case wifi connection fails
  ap:
    ssid: ${friendly_name} Hotspot
    password: !secret wifi_ap_password

ota:
  password: !secret ota_password

# Enable logging
logger: 
  level: DEBUG
  baud_rate: 0

captive_portal:

# restart 
button:
  - platform: restart
    name: Restart

sensor:
# Reports how long the device has been powered (in minutes)
  - platform: uptime
    name: Uptime
    filters:
      - lambda: return x / 60.0;
    unit_of_measurement: minutes

# water level sensor
# https://esphome.io/components/sensor/modbus_controller.html
  - platform: modbus_controller
    modbus_controller_id: qd
    name: "Water level"
    id: modbus_water_level
    register_type: holding
    address: 0x0004
    unit_of_measurement: "mm"
    value_type: S_WORD

# Reports the WiFi signal strength
  - platform: wifi_signal
    name: Wifi Signal
    update_interval: 60s

text_sensor:
  - platform: version
    name: ESPHome Version
  - platform: wifi_info
    ip_address: # exposes the IP Address when connected
      internal: true
      id: wifi_ip_addr
      name: "IP Address"

uart:
  id: mod_bus
  tx_pin: GPIO39
  rx_pin: GPIO37
  baud_rate: 9600
  data_bits: 8
  stop_bits: 1
  parity: NONE
  #debug: 

modbus:
  id: modbus1
  uart_id: mod_bus
  flow_control_pin: GPIO35

modbus_controller:
  - id: qd
    address: 0x01
    modbus_id: modbus1
    setup_priority: -10
    update_interval: 5s

status_led:
  pin:
    number: GPIO15

Thanks a lot to all!

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