The I-8077 Digital Input/Output Simulator Module are designed to be an aid to program development. Use the I-8077 to simulator real world inputs/outputs during your design and debug process. The I-8077 enables the program development to cause a change in input/output status at will to simulate a system active. And you can monitor status of Digital input/output on the Led. When it becomes time to move to real hardware or control program, replace the I-8077 with the appropriate digital input/output module. The logic of your program will remain the same.