Test with openmv-485(modbus)-plc,ide told me:crc not match。

test with openmv-485(modbus)-pc(imitate by soft), it is ok.
test with openmv-485(modbus)-PLC modbus (inovance AM403 ),ide told me:crc not match。
test with PLC modbus (inovance AM403 )–modbus sensor.it is ok.
every test is 9600,N,8,2:no parity, stop=2,slave id=2, plc is master

import time
from pyb import UART
from modbus import ModbusRTU
uart = UART(3,9600, parity=None, stop=2, timeout=1, timeout_char=4)
modbus = ModbusRTU(uart, slave_id=2,register_num=9999)

    if modbus.any():
        modbus.REGISTER[0] = 1000
        modbus.REGISTER[1] += 1
        modbus.REGISTER[3] += 3
        # image processing in there

what should i do now?

Modbus is an external library. We don’t support it. You can look at the library module to figure out what it’s doing. But, it’s user added code.

roger that