So, if I want to use that serial output for a 4th serial controlled device, exactly what do I need and where do I get it? I assume that this port can be used in the same manner that I have used the other 3 ports, but it just needs a different connect on one end, correct? I need a 9 pin serial connector on one end and appropriate wires on the other end. Perhaps it should have been clear to me from the responses above but I'm still not sure how to do that. Thanks, for your patience.
Marc