Troubleshooting ESP32 and Modbus Integration 🙏

ESPHome
1

Hey everyone,

I’m relatively new to the scene and don’t have much experience with electronics and programming, but I’m currently working on a project that involves an ESP32 microcontroller, a specific pinout configuration, and a power meter. However, I’ve encountered an issue and could really use some guidance. Here’s what I have:

  1. ESP32 with the following pinout: ESP32_DevKit_C_V4_Pinout.pdf (shopify.com)

  2. A power meter with the instructions available here: Eastron SDM220M* User Manual (xn–stromzhler-v5a.eu) an TTL to RS485 module:

    image
    image1440×1440 81.5 KB

  3. I have wired everything according to this diagram (of course the ESP and the power meter are connected to power supply):

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    image1019×348 82.7 KB

In my ESPHome configuration, I have the following code for this setup:

esphome:
  name: rs485
  friendly_name: Rs485

esp32:
  board: esp32dev
  framework:
    type: arduino

# Enable logging
logger:
  baud_rate: 0

uart:
  id: mod_bus
  tx_pin: GPIO1
  rx_pin: GPIO3
  baud_rate: 9600
  stop_bits: 2

modbus:
  flow_control_pin: GPIO0
  id: modbus1

modbus_controller:
  - id: controller
    ## the Modbus device addr
    address: 0x1
    modbus_id: modbus1

sensor:
  - platform: modbus_controller
    modbus_controller_id: controller
    name: "Currents sum"
    id: currents_sum
    address: 30049
    register_type: holding
    value_type: U_DWORD
    unit_of_measurement: "A"
    

# Enable Home Assistant API
api:
  encryption:
    key: "P/LTB5girwA0bT84O0lL7bLzGszImPRhWTBNQaSTeIs="

ota:
  password: "410734d9197a1988aea69177ccb0269c"

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

  # Enable fallback hotspot (captive portal) in case wifi connection fails
  ap:
    ssid: "Rs485 Fallback Hotspot"
    password: "lRKwYkASr0kA"

captive_portal:

However, when I check the logs, I see the following error message:
[D][modbus_controller:032]: Modbus command to device=1 register=0x1683 countdown=0 no response received - removed from send queue

Additionally, the entity associated with the power meter shows a status of “Unknown.”

I’m trying to figure out what I might be doing wrong here. Any tips or suggestions would be greatly appreciated. Thank you in advance!

Best regards, Felix

1 Like
2

First, try reversing the TX and RX lines from the ESP32 to the RS485 board. Some of these boards are mis-labelled.

3

Hello, sadly this doesn’t change anything :frowning:
Is it normal that when I set 0x0006 as the sensor address, the resulting error message has 0x06 as its address?

4

Better use a XY-017 as it only needs 3.3 V volt power instead of 5V of the one you have now
Also it doesn’t need the flow control pin anymore
Inexpensive RS485 interface board for ESP8266/ESP32/Arduino | Жизнь, бизнес и IT (bizkit.ru)
RS485 naar RX-TX TTL 3.3V 5V omvormer module SP3485 (domoticx.nl)

I have made many espboards with this ttl to rs485 and found no problems.
With the other board i have had many CRC errors.

You might want to try sdm_meter
Eastron SDM Energy Monitor — ESPHome

esphome/sdm_meter_registers.h at dev · esphome/esphome · GitHub

5

Yea will try that.
Untill these arrive, no solution. :frowning:

6

if it is the 3.3v vs 5v i wonder is a logic level shifter would help? i know i have quite a few laying around and my local electronics store has them in stock… saves waiting for parts from overseas

7

I have some xy-017 at home. If you live in the Netherlands/Belgium i could send one.
Also have fully assembled PCB’s with esp32 (mh-et-live)

Not tested with a level shifter, as it is another component added to the material lists :wink:

8

Update:
It somehow started to work perfectly. ¯_(ツ)_/¯
Maybe I forgot to connect DE and RE

1 Like
9

May i ask how you connected DE and RE? to which pins on the ESP 32?

10

It looks like he connected GPIO0 (flow_control_pin) to RE and bridged RE and DE.
Another ref: microcontroller - Correctly using RE and DE with RS485 - Electrical Engineering Stack Exchange