mp_modbus

Modbus Lib for Micropython

mp_modbus_frame

Create a modbus frame (you shouldn't have to do it by yourself):

from mp_modbus_frame import modbus_rtu_frame, modbus_tcp_frame

# RTU
rtu_frame = modbus_rtu_frame(
    device_addr=1,    # slave address
    func_code=3,      # function code
    register=100,     # requested register
    length=2,         # number of requested registers
    fr_type="request" # type of frame
  )

# or parsing:
rtu_frame = modbus_rtu_frame.parse_frame(
  bytearray([0x01, 0x03, 0x00, 0x12, 0x00, 0x08, 0xe4, 0x09])
  )

# TCP
tcp_frame = modbus_tcp_frame(
    transaction_id=1, # transaction id
    unit_id=1,        # unit id
    device_addr=1,    # slave address
    func_code=3,      # function code
    register=100,     # requested register
    length=2,         # number of requested registers
    fr_type="request" # type of frame
  )  

# or parsing:
tcp_frame = modbus_tcp_frame.parse_frame(
  bytearray([0x00, 0x01, 0x00, 0x00, 0x00, 0x06, 0x01, 0x03, 
      0x00, 0x12, 0x00, 0x08])
  )

mp_modbus_master

RTU-Master or TCP-Client:

from mp_modbus_master import modbus_rtu_master, modbus_tcp_client

# RTU
rtu_master = modbus_rtu_master(
  uart_no=2, parity=0, tx_pin=12, rx_pin=13, en_pin=32
  )

frame = rtu_master.read_holding_registers(305, 1)
print(frame.data)

# TCP