940-0024C Cable Wiring~

Supported Models: SmartUPS (all models with DB9 serial port)

Wiring Diagram~

Signal	Computer (DB9F)	UPS (DB9M)	Function
RxD	2	2	TxD (Send)
TxD	3	1	RxD (Receive)
DCD	1		Internally tied to DTR (Pin 4)
DTR	4		Internally tied to DCD (Pin 1)
GND	5	9	Ground
RTS	7		Internally tied to CTS (Pin 8)
CTS	8		Internally tied to RTS (Pin 7)

Note: On the Computer (DB9F) side, pins 1 & 4 (DCD & DTR) and pins 7 & 8 (RTS & CTS) are internally connected.

graph LR
  %% Define computer side (DB9F)
  subgraph Computer [Computer DB9F]
    DCD1["Pin 1: DCD"]
    RxD2["Pin 2: RxD"]
    TxD3["Pin 3: TxD"]
    DTR4["Pin 4: DTR"]
    GND5["Pin 5: GND"]
    RTS7["Pin 7: RTS"]
    CTS8["Pin 8: CTS"]
  end

  %% Define UPS side (DB9M)
  subgraph UPS [UPS DB9M]
    RxD1["Pin 1: RxD"]
    TxD2["Pin 2: TxD"]
    GND9["Pin 9: GND"]
  end

  %% Inter-device connections
  RxD2 --- TxD2
  TxD3 --- RxD1
  GND5 --- GND9

  %% Internal wiring on the computer side
  DCD1 --- DTR4
  RTS7 --- CTS8