2. X.21 byte tim ing ca ble - (15 way to 15 way D type plugs).
CCITT cir cuit Tim ing Source (DCE) Tim ing Sink (DTE) CCITT cir cuit
T-A 2 4 R-A
T-B 9 11 R-B
R-A 4 2 T-A
R-B 11 9 T-B
B-A 14 1 SEXT-A
B-B 7 15 SEXT-B
I-A 5 3 C-A
I-B 12 10 C-B
C-A 3 5 I-A
C-B 10 12 I-B
GND 8 8 GND
3. V.24 / V.28 bit tim ing ca ble - ( 25 way to 25 way D type plugs).
CCITT cir cuit Tim ing Source (DCE) Tim ing Sink (DTE) CCITT cir cuit
103 2 3 104
104 3 2 103
105 4 8 109
102 7 7 102
109 8 4 105
115 17 24 113
4. V.35 bit tim ing ca ble - (34 way to 34 way MRAC plugs).
CCITT cir cuit Tim ing Source (DCE) Tim ing Sink (DTE) CCITT cir cuit
103-A P R 104-A
103-B S T 104-B
104-A R P 103-A
104-B T S 103-B
105 C F 109
109 F C 105
115-A V U 113-A
115-B X W 113-B
GND B B GND
A-11
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