APC Dumb UPS cable (simple)

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connector or cable wiring APC Part# 940-0020 (grey cable). Should work with APC PowerChute Plus software.

9 pin D-SUB male connector layout 9 pin D-SUB male connector to the UPS

9 pin D-SUB female connector diagram 9 pin D-SUB female connector to the computer

This cable can only be used on voltage-signalling UPSes, and provides the On Battery signal as well as kill UPS power (and may be Low Battery signal).

UPS Signal Name DB-9 Male (UPS end) DB-9 Female (PC end) PC Signal Name
Shutdown 1 4 DTR
AC Fail 2 8 CTS
Common 4,9 5 GND
         APC Part# - 940-0020B (investigated by apcupsd team) 
         Signal Computer                  UPS 
                DB9F                     DB9M 
          CTS    8   --------------------  2  On Battery 
          DTR    4   --------------------  1  Kill power 
          GND    5   ---------------*----  4  Ground 
                         ---        *----  9  Common 
          DCD    1  ----|///|-----------   5  Low Battery 
          RTS    7  ----|///| (probably a 
                         ---   semi-conductor) 

Note: sides swapped. Full scheme of 940-0020C isn’t yet known.

     APC Part# - 940-0020C (investigated by apcupsd team)      Signal Computer                  UPS             DB9F                     DB9M       CTS    8   --------------------  2  On Battery       DTR    4   --------------------  1  Kill power       GND    5   ---------------*----  4  Ground                                 |                                 *----  9  Common       RTS    7 -----[ 93.5K ohm ]----- 5  Low Battery                     or semi-conductor                    


  • Someone reports that the 20C is designed to mimic a mouse movement when it received an on battery signal from the Back-UPS. Therefore the computer will wake up and shutdown properly. The 20B cable does not have this functionality.


Category:Miscellaneous Cables


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