I am doing a project on PC-based control process. I am using the NuDam 7050 card as a digital I/O card, to interface between the PC and a load. The other port on the 7050 card is used up, except the port (R)+Vs, I do not know what the port is used for and how should it be connect up and to where. Please kindly leave me your comments and the best an solution to my problem. Thank you.