While each legacy interface has its own settings file, the communication settings are the same in each file. 
The settings file for each interface is the program name with an extension of "FIL".

Read this Wikipedia article if you need help understanding serial ports.

This is an example of the communication settings found at the bottom of each of the interface settings files:

Setting	Description
WINPORTNO	This is the port number into which the interface is physically connected or the virtual port configured by the customer's technician. Serial port numbers are assigned by the operating system and it's the responsibility of the customer or the customer's technician to determine the specific port number into which the serial cable has been plugged. This setting begins at 0, so Com1 = 0, Com2 = 1, etc.
WINBAUDRT	This is the baud rate of the interface and is determined by the 3rd party system. 9600 is the maximum baud rate supported.
WINPARITY	This is the parity of the interface and is determined by the 3rd party system. The settings are N = None, E = Even, O = Odd, M = Mark, S = Space N is the most common setting, followed by E.
WINDATALN	This is the data bits length and is determined by the 3rd party system. The settings are 7 and 8. 8 is the most common setting. 7 is used along with a WINPARITY setting of E or O.
WINSTOPBT	This is the stop bits setting of the interface and is determined by the 3rd party system. The settings are 1 and 2. 1 is the most common setting. 2 is rarely used and usually only with very old systems.
WINRDMETH	This setting should always be blank.
WINRDTERM	This setting should always be -2.

You'll often hear the phrases like, "9600, eight, none and one" or "1200, seven, even and one" when referring to serial communication settings. These are common ways of referring to the communication settings of the interface and mean:
"9600, eight, none and one"
Baud = 9600
Data Bits = 8
Parity = N
Stop Bits = 1

"1200, seven, even and one"
Baud = 1200
Data Bits = 7
Parity = E
Stop Bits = 1

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Troubleshooting the connection

There are only a couple things you can do to troubleshoot serial communication. After you make a change to a setting, safe the file and restart the interface.

1. The first, and most critical step, is to determine the proper serial port number. Without certainty, you may be wasting your time with all other troubleshooting.
2. The second step, after being certain of the serial port number, is to try different Baud Rate, Data Bits, Parity and Stop Bits. Often, you'll at least get garbage if the correct serial port setting is being used. Garbage is usually an indication of an incorrect baud rate, but could be caused by a discrepancy in the other settings as well. 
3. For troubleshooting help when a technician isn't available, try this page. Troubleshooting Serial Connections