I can't get my PLC to talk to my MI HMI, what can I do?

1) Check the cabling is correct, and the correct pin outs are being used
both ends, HMI and PLC.
2) Check that the port setup (baud rate, parity, data bits, stop bits)
match both ends. In some PLCs these items are configurable, so check
that everything matches.
3) Check that the 'device address' configured in the device properties
matches the device address (or node id) of the PLC.
4) Check that you are connecting to the correct port on the HMI.
5) Check that the protocol you have selected is correct for the PLC and
port on the PLC.
6) If the protocol is RS232 (or if you have an RS232RS485 converter),
try connecting the HMI port to a PC running HyperTerminal. Verify that
the HMI is transmitting characters that look sensible.
7) Try configuring an intermessage delay within the port settings in
Configuration Manager. It may be the HMI is transmitting too quickly for
the PLC.