How to know DCE equipment /what serial cable to buy


Active Member
How do you know per application whether to use null modem or straight through?

PC <-> PC = null modem
PC <-> DCE = straight through

My Equipment: elk serial expander / global cache / pc
Down the road, hopefully a denon and other controllable AV equipment...

So, on the GC/Elk/Denon - Are these all considered "DCE"?
such that PC to any of them would be stright through?
between each other would be null?

The two types of serial equipment are DCE and DTE. The primary difference is if they transmit on pin 2 versus pin 3. I find it very difficult to keep serial cables organized and tagged, so when I am testing something I just use whatever cable I have handy. If it doesn't work, I add a null modem adapter. It has to work one way, with or without the adapters, so you always have a 50/50 shot of getting it right the first time, assuming baud, etc are correct. If you are wiring something permanently, then you can acquire the proper cable, if desired. but there are lots of online sources for these around $2 each.