MicroPython Modbus library
MicroPython ModBus TCP and RTU library supporting client and host mode
General
Forked from Exo Sense Py, based on PyCom Modbus and extended with other functionalities to become a powerfull MicroPython library
The latest documentation is available at MicroPython Modbus ReadTheDocs
Quickstart
Install package on board with pip
Request coil status
TCP
RTU
Install additional MicroPython packages
Usage
Supported Modbus functions
Credits
Quickstart
This is a quickstart to install the micropython-modbus
library on a
MicroPython board.
A more detailed guide of the development environment can be found in SETUP. Further details about the usage can be found in USAGE
python3 -m venv .venv
source .venv/bin/activate
pip install 'rshell>=0.0.30,<1.0.0'
Install package on board with pip
rshell -p /dev/tty.SLAB_USBtoUART --editor nano
Inside the rshell open a REPL and execute these commands inside the REPL
import machine
import network
import time
import upip
station = network.WLAN(network.STA_IF)
station.active(True)
station.connect('SSID', 'PASSWORD')
time.sleep(1)
print('Device connected to network: {}'.format(station.isconnected()))
upip.install('micropython-modbus')
print('Installation completed')
machine.soft_reset()
Request coil status
After a successful installation of the package and reboot of the system as described in the installation section the following commands can be used to request a coil state of a target/client device. Further usage examples can be found in the examples folder and in the Micropython section of USAGE
TCP
from ummodbus.tcp import ModbusTCPMaster
tcp_device = ModbusTCPMaster(
slave_ip='172.24.0.2', # IP address of the target/client/slave device
slave_port=502, # TCP port of the target/client/slave device
# timeout=5.0 # optional, timeout in seconds, default 5.0
)
# address of the target/client/slave device on the bus
slave_addr = 10
coil_address = 123
coil_qty = 1
coil_status = host.read_coils(
slave_addr=slave_addr,
starting_addr=coil_address,
coil_qty=coil_qty)
print('Status of coil {}: {}'.format(coil_status, coil_address))
RTU
from umodbus.serial import ModbusRTU
host = ModbusRTU(
addr=1, # address of this Master/Host on bus
# baudrate=9600, # optional, default 9600
# data_bits=8, # optional, default 8
# stop_bits=1, # optional, default 1
# parity=None, # optional, default None
pins=(25, 26) # (TX, RX)
)
# address of the target/client/slave device on the bus
slave_addr = 10
coil_address = 123
coil_qty = 1
coil_status = host.read_coils(
slave_addr=slave_addr,
starting_addr=coil_address,
coil_qty=coil_qty)
print('Status of coil {}: {}'.format(coil_status, coil_address))
Install additional MicroPython packages
To use this package with the provided boot.py
and
main.py
file, additional modules are required,
which are not part of this repo/package. To install these modules on the
device, connect to a network and install them via upip
as follows
import upip
upip.install('micropython-brainelectronics-helpers')
Check also the README of the brainelectronics MicroPython modules and the SETUP guide
Usage
See USAGE
Supported 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 |
Credits
Big thank you to giampiero7 for the initial implementation of this library.
sfera-labs - Initial work - giampiero7
pycom - Initial Modbus work - pycom-modbus
pfalcon - Initial MicroPython unittest module - micropython-unittest