You have provided no information on what hardware you have in the interface cabinet, how many chambers you have, how many inputs/outputs there are per chamber etc. It is very difficult to advise on how to proceed.
The only advice that I can provide given the information that I have is to run the MED-PC Hardware Configuration Utility (Start | Programs | MED Associates | MED-PC IV | Hardware Configuration Utility).
When the program starts go to Define | Guided Sequence.
If you have a standard setup of all SmartCtrl or all SuperPort cards, then answering the questions in the Guided Sequence should setup the DTA file correctly for you.
If you have a setup that contains a mix of different cards, then it would be best for you to call MED Associates when you can be in front of the computer. They will help walk you through setting up the DTA file and also make sure that all of the cards are configured correctly.
Gary