APC SmartUPS Serial Cable Pinout

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.apc-smart-ups-serial-pinout


6 comments on “APC SmartUPS Serial Cable Pinout”

  1. Hi, you have the SmartUPS cable slightly wrong. The picture is correct, but you have counted the pins on the male connector incorrectly. The correct table should be:
    Fem Male
    2 2
    3 1
    5 9


  2. Mr Ball (posted on 7/3/2009) is correct you should correct the db9 male side pin numbers. Other wise nice diagram!

  3. I’ve got with my APC 620 a cable imprinted 940-0024c with your pin assignments, just to confirm. Checked for R of 10K, but no resistors found.

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