ITU-TSS V.35 Serial

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Image:connector_m34m.png 34 pin M/34 male connector.

Image:connector_m34f.png 34 pin M/34 female connector.

Basically, V.35 is a high-speed serial interface designed to support both higher data rates and connectivity between DTEs or DCEs over digital lines.

Pin Name Dir Description
A - Chassis Ground
B - Signal Ground
C RTS OUT Request To Send
D CTS IN Clear To Send
E DSR IN Data Set Ready
F DCD IN Data Carrier Detect
H DTR OUT Data Terminal Ready
J LL IN Local Loopback
K OUT Local Test
L unused
M unused
N unused
P TxD- OUT Send Data A
R RxD- IN Receive Data A
S TxD+ OUT Send Data B
T RxD+ IN Receive Data B
U OUT Terminal Timing A
V IN Receive Timing A
W OUT Terminal Timing B
X IN Receive Timing B
Y IN Send Timing A
Z unused
AA IN Send Timing B
BB unused
CC unused
DD unused
EE unused
FF unused
HH unused
JJ unused
KK unused
LL unused
MM unused
NN unused

V.35 is an interface (V.35 is the ITU - formerly CCITT standard termed “Data Transmission at 48 Kbps Using 60-108 KHz Group-Band Circuits”) commonly used on higher speed circuits of 56kbps and above. Recognizable by its blocky, 34-pin connector; V.35 combines the bandwidth of several telephone circuits to provide the high-speed interface between a DTE or DCE and a CSU/DSU (Channel Service Unit/Data Service Unit). To achieve such high speeds and great distances, V.35 combines both balanced and unbalanced voltage signals on the same interface. Transmission is usually a synchronous protocol (note clocking pins i.e. receive and transmit clock). Although V.35 is commonly used to support speeds ranging anywhere from 48 to 64 Kbps, much higher rates are possible [ ISDN (64 or 128Kbps), Factional T1@ 128 Kbps to 1.544Mbps T1, ATM and Frame Relay]. V.35 cable distances theoretically can range up to 4000 feet (1200 m) at speeds up to 100 Kbps. Actual distances will depend on your equipment and the quality of the cable . Lan routers often come equipped with a V.35 electrical interface but many today are using a HSSI interface at speeds higher than T1 and above (typical T3 45Mbps).

V.35 cable is balanced multipair with characteristic impedance 80-120 Om at the fundamental frequency. Voltage is 0.55v+/-20% with 100 Ohm load.

There seem to be two versions of the V.35 pinning. One is called V.35 Winchester, the other is called V.35 Straight. One is mirrored to the other. We don”t know how it is mirrored. This information came from a 3Com source. Their Access Builder 4000 V.35 Card interface is V.35 Straight they say. The Dutch PTT supplies V.35 interface according to V.35 Winchester. Connecting these two requires some sort of crossed cable.


Category:Serial Connectors


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