COMM1 is just a RS232 port that uses only Tx, Rx and GND (2,3,5). You need to make a cable to connect to your MODBUS or OMRON slave. It is either:
2 - 2
3 - 3
5 - 5
or
2 - 3
3 - 2
5 - 5
The next thing to do is to use the SETBAUD function to set the baudrate of COMM1 to the same as your slave. (Alternatively, you can also set your slave's baud rate and communication to that of the PLC, which is by default 38,400, 8, 1, noparity.
To talk to a MODBUS slave, use the READMODBUS (11, x,x) or WRITEMODBUS ?11, x, x, x
To talk to OMRON slave, use the NETCMD$.
Please read the documentation on how to use the NETCMD$, READMODBUS and WRITEMODUS commands in your programmer's reference.
