I replaced my old APC SmartUPS 620 with an updated model. I had lost the serial cable that allows you to communicate with the UPS via a computer for the old unit. The new unit came with the serial cable and for a while, I was looking for the correct pinout so I could build a cable myself. So I wanted to get the pin out documented. The cable is a male to female DB9 cable. Well I got my voltmeter and using the continuity setting I mapped the pinout. It would not be difficult to create this cable. Many of the cables DB9 serial cables I had laying around were female to female and it was hard finding a male end. Hopefully, this will help others out there that need this cable and don’t want to pay $30 for it.
UPDATE: I have updated the diagram based on the comments I got on this post. Apparently, I counted the male pins incorrectly so I made the correction. Thanks for your feedback.