A Made IT project

V.35

General
V.35 is a partially balanced, partially single-ended interface specification. The data leads and clock leads are balanced, the handshake leads are single-ended. Most commonly used for 56kbps and 64kbps data rates.

	DATA LEADS		CONTROL LEADS
Vdc	B > A	A > B	-3 to -25	+3 to +25
binary	1	0	1	0
signal	MARK	SPACE	MARK	SPACE
function	off	on	off	on

Transmitter output voltage from a balanced tranmitter indicating a MARK is +0.35Vdc for the B line, -0.2Vdc for the A line. Indication of a SPACE condition is +0.35Vdc for the A line, -0.2Vdc for the B line. Output voltage difference is 0.55Vdc. To make sense to the receiver it must be at least 0.01Vdc difference between the A line and B line. Maximum cable length depends on required speed and cable capacitance. The extremes specified are 2000ft/600m to 4000ft/1200m @ 100kbps, 300ft/90m at 10Mbps. Sync applications only, no async V.35 equipment around.

More speed/distance equations: 610m @ 64 kbps.

Pinning


M/34 Male	M/34 Female

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

Special Notes
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. Crossed pinning presently unknown. If someone has more information please let us know!

There are two versions of V.35 screw locks. The US-version measures 16/10 mm (the large one), the French version measures 10/10 mm (the small one). The US-version is also known as Domestic and the French version is also called International.

V.35 Cross Cable
A	-	A
B	-	B
C	-	F
F	-	C
E	-	H
H	-	E
R	-	P
T	-	S
P	-	R
S	-	T
V	-	U
X	-	W
U	-	V
W	-	X

Resources: