Panasonic KX-TG7731S Service Manual page 57

12.2.2. Connections (Handset)
Connect the DC Power or Battery to BATT+ and BATT-.
Connect the JIG cable GND (black) to GND.
Connect the JIG cable UTX (yellow) to UTX and URX (red) to URX.
DC Power
1
or Battery
Note:
*: COM port names may vary depending on what your PC calls it.
URX
BATT+
Handset P. C. board
URX (red)
3
3 UTX (yellow)
UTX
GND (black)
2
GND
BATT-
JIG Cable
57
KX-TG7731S/KX-TG7732S/KX-TG7733S/KX-TGA470S
To Serial Port
(com port 1*)
PC