1

Currently, I'm using pymodbus to read data from a few slave devices. I discovered that even if the connecting fails, the script would still continue regardless instead of just failing. I want it to just fail properly so that I can catch the error itself.

Below is the function I made for establishing a connection.

def init485(port_in, baudrate_in):
    client = ModbusClient(method="rtu", port=port_in, stopbits=1 ,bytesize=8 ,parity="N", baudrate=baudrate_in, timeout=3) 
    connection = client.connect()
    print("Connecting to", port_in, "...")
    sleep(5)
    if (connection is True):
        print("Connection successful at", getcurrenttime())
    else:
        print("Failed to connect. Please check if settings are correct.")
        sleep(2)
    return connection, client

And below that is the try-except within a while loop.

while True:
    try:
        c = init485("/dev/ttyUSB0", 9600)
        connection = c[0]
        mb_client = c[1]
        while (connection is True):
            ...
    except:
        mb_client.close()
        print("Failed")
        sleep(60)

The idea is that if the connection to the port fails, it'd catch and print "Failed". Right now, it's just stuck in the while loop. Is there a way to make it work? The error I want to catch is this:

ERROR:pymodbus.client.sync:could not open port '/dev/ttyUSB0': FileNotFoundError(2, 'The system cannot find the path specified.', None, 3)
Amerul Atiq
  • 51
  • 4
  • 1
    From what I'm reading, It doesn't look like that is possible yet in that way, however there is another method to do so which is specified in the following, however it is said to be "unpythonic" Reference: https://github.com/riptideio/pymodbus/issues/298 – damaredayo Sep 08 '21 at 10:29

0 Answers0