Ecosyste.ms: Awesome
An open API service indexing awesome lists of open source software.
https://github.com/gmasse/esp-modbus-mqtt
A Modbus RTU (RS-485) to MQTT Gateway (based on ESP32)
https://github.com/gmasse/esp-modbus-mqtt
esp32 home-automation iot modbus mqtt platformio
Last synced: 6 days ago
JSON representation
A Modbus RTU (RS-485) to MQTT Gateway (based on ESP32)
- Host: GitHub
- URL: https://github.com/gmasse/esp-modbus-mqtt
- Owner: gmasse
- License: gpl-3.0
- Created: 2020-03-07T13:37:42.000Z (over 4 years ago)
- Default Branch: master
- Last Pushed: 2024-05-07T23:46:23.000Z (6 months ago)
- Last Synced: 2024-10-15T03:21:39.972Z (22 days ago)
- Topics: esp32, home-automation, iot, modbus, mqtt, platformio
- Language: C++
- Homepage:
- Size: 453 KB
- Stars: 81
- Watchers: 10
- Forks: 28
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
## Circuit
Auto-switching UART-to-RS485 converter:
```
VCC ---------------+
|
+-------x-------+
(PIN27) RXD <------| RX |
| UART B|----------<> B
(PIN26) TXD ------>| TX TO |
ESP32 | RS-485 | RS485 bus side
| |
| A|----------<> A
| |
+-------x-------+
|
GND
```
Manual switching UART-to-RS485 converter:
```
VCC ---------------+
|
+-------x-------+
(PIN27) RXD <------| R |
| UART B|----------<> B
(PIN26) TXD ------>| D TO |
ESP32 | RS-485 | RS485 bus side
(PIN25) RTS --+--->| DE |
| | A|----------<> A
+----| /RE |
+-------x-------+
|
GND
```
NB: ESP32 pins are configurable at compilation time.
## Modbus
Device acts as Modbus Master, regurlaly polling a list of registers from a Modbus Slave.
List of Modbus parameters (in `platformio.ini` file):
- `modbus_rxd`: RX/R pin number (default: `27`)
- `modbus_txd`: TX/D pin number (default: `26`)
- `modbus_rts`: DE/RE pin number (default: `25`). If you don't need RTS, use `NOT_A_PIN` value.
- `modbus_baudrate` (default: `9600`)
- `modbus_unit`: Modbus Slave ID (default: `10`);
- `modbus_retries`: if a Modbus request fails, number of retries before passing to the next register (default: `2`)
- `modbus_scanrate`: the device will attempt to poll the slave every XX seconds (default: `30`)
Registers list is defined by the array `registers[]` in `src/modbus_registers.h`.
A very simple example would be:
```
const modbus_register_t registers[] = {
{ 123, MODBUS_TYPE_HOLDING, REGISTER_TYPE_U16, "value_123" },
{ 124, MODBUS_TYPE_HOLDING, REGISTER_TYPE_U16, "value_124" }
};
```
Where:
- `123` and `124` are register address to read,
- `MODBUS_TYPE_HOLDING` is the Modbus object type to read,
- `REGISTER_TYPE_U16` is the expected format of the returned value,
- `value_123` and `value_124` are the name in the JSON MQTT message
#### Supported Modbus objects:
- `HOLDING` type is supported and has been tested
- `INPUT`, `COIL`, `DISCRETE` and `COUNT` has not been tested but should work
#### Supported returned Value:
- `REGISTER_TYPE_U16`: unsigned 16-bit integer
- `REGISTER_TYPE_BITFIELD`: a sequence of 16 (or less) single bits; the first item maps the least significant bit
- `REGISTER_TYPE_DIEMATIC_ONE_DECIMAL`: a specific De-Dietrich signed decimal implementation
- `REGISTER_TYPE_DEBUG`: hexadecimal value only visible in INFO logs (not sent in MQTT message)
- other types are not supported (TODO src/modbus_base.cpp:readModbusRegisterToJson)
## MQTT
MQTT parameters are passed through environment variables:
- `PIO_MQTT_HOST_IP`: MQTT broker IPv4
- `PIO_MQTT_PORT`: MQTT broker port
- `PIO_MQTT_TOPIC`: root prefix of the published topic
With `PIO_MQTT_TOPIC=MyTopic`, based on the register list example above, the published MQTT message will be:
```
Topic: MyTopic/ESP-MM-ABCDEF012345/data
Message: {"value_123":0,"value_124":65536}
```
Where `ABCDEF012345` is the ESP unique Chip ID.
## Compilation
```
git clone https://github.com/gmasse/esp-modbus-mqtt.git
cd esp-modbus-mqtt
python3 -m venv venv
source venv/bin/activate
pip install -U platformio
hash -r
cp platformio.ini.dist platformio.ini
(edit platformio.ini if needed)
export PIO_FIRMWARE_URL="http://domain.com/firmware.bin"
export PIO_MQTT_HOST_IP=11.22.33.44
export PIO_MQTT_PORT=1883
export PIO_MQTT_TOPIC=mytopic
platformio run
```
Built firmware will be at `.pio/build/fm-devkit/firmware.bin`
You can upload to ESP with: `platformio run upload`
## TODO
- [ ] Configuration (Wifi credentials) Reset
- [ ] Factory Firmware (https://docs.espressif.com/projects/esp-idf/en/latest/api-guides/bootloader.html)
- [ ] Secure Boot
- [ ] Moving to ESP-IDF Framework
- [ ] Log level update at runtime
## FAQ
#### Passing environment variables via VS Code
Edit `.vscode/settings.json` and add the following lines:
```
"terminal.integrated.env.osx": {
"PIO_FIRMWARE_URL": "https://url/firmware.bin",
"PIO_MQTT_HOST_IP": "11.22.33.44",
"PIO_MQTT_PORT": "1883",
"PIO_MQTT_TOPIC": "mytopic"
},
```
#### Flashing firmware
```
cp .plateformio/packages/framework-arduinoespressif32/tools/sdk/bin/bootloader_dio_40m.bin .
cp .platformio/packages/framework-arduinoespressif32/tools/partitions/default.bin .
esptool.py --chip esp32 --port /dev/ttyUSB1 --baud 460800 \
--before default_reset --after hard_reset write_flash -z \
--flash_mode dio --flash_freq 40m --flash_size detect \
0x1000 bootloader_dio_40m.bin 0x8000 default.bin 0x10000 firmware.bin
```