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9 pin D-SUB male connector layout
9 pin D-SUB male connector
APC Part# 940-0024C, # 940-0024B, # 940-0024D or 940-1524(black cable). Compatible with most APC UPSs that have a DB9 serial port. Should work with APC PowerChute or Apcupsd(UPS Server for Linux)

Should be compatible with: 

  • Back-UPS Pro    BP650, BP650S, BP650SC, BP420, BP420S, BP420SC, BP280S (also compatible with  940-0095B cable)
  • Smart-UPS 3G    SU420NET, SU620NET, SU700NET, SU1000NET, SU1400NET, SU2200NET, SU3000NET, SU2200XLNET, SU2200XLTNET, SU3000TNET, SU5000T, SU1400RMXL3U, SU2200RM3U, SU2200RMXL3U, SU2200RMXLNET, SU2200RMXLTNET, SU3000RM3U, SU3000RMNET, SU3000RMT3U, SU3000RMXL3U, SU5000, SU5000RMT5U
  • Smart-UPS 3.5G    SU700RM2U, SU1000RM2U, SU1400RM2U
  • Smart-UPS 3.6G(Serial)    SUA1000, SUA1500, SUA750XL, SUA1000XL
  • Smart-UPS 4.0G(Serial)    SUA2200, SUA2200RM2U, SUA3000, SUA3000RM2U, SUA3000RMT2U
  • Smart-UPS SC    SC420, SC620
  • Matrix    MX3000, MX5000, MX3000XR, MX5000XR


APC Part# 940-0024A, 940-0024B, 940-0024C, 940-0024D, 940-1524  cable scheme

According to APC forum, letter suffix is related to (change of?) manufacturer or revision, not wiring, and cables are electrically interchangable.

'Simple scheme' diagram further below looks correct for 940-0024 & A,B,C or D revisions and 940-1524 which is 15' long cable; and matches what viewed on a third-party site. 


Simple scheme (APC 940-1524D cable)

Signal Name
DB-9 Male
(UPS end)
DB-9 Female
(PC end)
Signal Name
TX / AC Fail 2 2 Rx, Received Data
RX / Shutdown 1 3 Tx, Transmitted Data
Common 9 5 GND

At the PC end: pins 1,4 (DCD, DTR) shorted; pins 7,8 (RTS, CTS) shorted.
DB-9 shells are also connected.

The 9,1,2 pins look OK for the basic mode, but the smart mode seems to need extra components.



Alternative scheme. Smart UPS Console Cable  APC part # is unknown.

DB 9 PC Male

UPS DB 9 Female


1 & 2


RX??  Short Pins 1 & 2 on PC side connect to Pin 2 on UPS side



TX ??



No Connection






No Connection

7 & 8


Short Pin 7 & 8 on PC side.

Terminal Set Up:

2400 baud 8 bit no parity 1 stop no handshake.

Apply the port settings to establish the connection.
 Press 3-5 times to display the username prompt.
The default SmartUPS username is apc and default password is apc


9 pin D-SUB female connector layout
9 pin D-SUB female connector
According to 73 reports in our database (70 positive and 2 negative) the APC Smart UPS DB9 cable pinout should be correct.

Is this pinout
APC Smart UPS DB9 cable visual pinout:click to enlarge
Source(s) of this and additional information: UPS FAQ in russian,
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