Micropython Modbus library

Forked from Exo Sense Py, based on PyCom Modbus and extended with other functionalities to become a powerfull micropython library

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Installation

Change network settings

The network settings are defined in the config_network.py file. It is possible to use a single network, trying to connect to different networks or creating an AccessPoint.

Copy files

Copy all python files (plus index.html) in this repo to the device.

ampy

ampy has several drawbacks compared to rshell, consider using rshell

python3 -m venv .venv
source .venv/bin/activate

pip install adafruit-ampy

Place a file named .ampy in the local directory, as proposed on the ampy README

nano .ampy

# Please fill in your own port, baud rate, and delay
AMPY_PORT=/dev/cu.wchusbserial1410

AMPY_BAUD=115200

# Fix for macOS users' "Could not enter raw repl"; try 2.0 and lower from there:
AMPY_DELAY=0.5

Perform the following command to copy all files and folders to the device

ampy mkdir lib
ampy mkdir lib/uModbus

ampy put lib/uModbus/*.py lib/uModbus

ampy put boot.py
ampy put config.py
ampy put config_network.py
ampy put index.html
ampy put main.py
ampy put modbus.py
ampy put time_helper.py
ampy put webserver.py
ampy put wifi_helper.py

rshell

python3 -m venv .venv
source .venv/bin/activate

pip install rshell

Open the remote shell with the following command

rshell -p /dev/tty.wchusbserial1410 -b 115200 --editor nano

Perform the following command to copy all files and folders to the device

mkdir /pyboard/lib
mkdir /pyboard/lib/uModbus

cp lib/uModbus/* /pyboard/lib/uModbus
cp *.py /pyboard
cp index.html /pyboard

Usage

Start a REPL (may perform a soft reboot), wait for network connection and start performing Modbus requests to the device

Device configuration

All configuration parameters are in the config.py file.

To access this file on the module join its WiFi network or AccessPoint. A Web server will be enabled by default. Use a Web browser to connect to 192.168.4.1 using the credentials specified in the config.py configuration file.

Refer to config_network.py for the default WiFi and AccessPoint credentials.

Download the configuration file, edit it and re-upload it. If using the Web interface, after the upload, the device will automatically restart using the new configuration, otherwise, on the next power-on, it will start with the new configuration.

Register configuration

The available registers are defined by a JSON file, which can be up/downloaded from the device by a simple and lightweight webserver.

Configure it to work as Modbus RTU slave or Modbus TCP server, by setting MB_RTU_ADDRESS or MB_TCP_IP to a valid value. If both are set, the TCP configuration will be ignored. If neither are, it will boot as not configured and endup in the REPL.

When configured as Modbus TCP server, the configuration Web interface will be available at the configured IP address.

Modbus functions

Refer to the following table for the list of supported Modbus functions.

ID	Description
1	Read coils
2	Read discrete inputs
3	Read holding registers
4	Read input registers
5	Write single coil
6	Write single register
15	Write multiple coils
16	Write multiple registers