Pinout For Serial Ports
What is the pinout for my serial port? What pins do I need to connect for a loop back test?
RS-232 is the single ended serial protocol and RS-485 and RS-422 are differential serial protocol. The pinout for RS-232, RS-422 and RS-485 is shown below figure.
A loopback test is a test in which a signal in sent from a communications device and returned (looped back) to it as a way to determine whether the device is working right. The figures below will show you what pins you need to connect to perform loopback test on RS-232 and RS-422/RS-485 respectively.
RS-422 and RS-485
Example Program: Serial Loop Back Test for LabVIEW
KnowledgeBase 2WR9LNHW: How Do I Do a Loop Back Test with a 485 Port in Two Wire Mode?
- Serial ports.bmp
- RS-232 loopback.bmp - RS-485 and 422 Loopback.bmp
Report Date: 04/24/2007
Last Updated: 12/28/2015
Document ID: 48NB9TBH