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AIXLink/X.25 1.1 for AIX: Guide and Reference

Modem Attachment Pin Assignments

Supported modem types include the V.11, V.24/X.21bis, and V.35/X.21bis attachments.

X.21 Pin Assignments

The following table describes the pin assignments of the V.11 interface circuits for 15-pin connectors.

Pin Assignments of V.11 Interface Circuits to 15-Pin Connectors
Pin Number Circuit Assignment Circuit Description
11 - -
2 T(a)2 Transmit
3 C(a) Control
4 R(a) Receive
5 I(a) Indication
6 S(a) Signal element timing
7 B(a)/X(a) Byte timing: Modem transmit signal
8 G Signal ground or common return
9 T(b)2 Transmit
10 C(b) Control
11 R(b) Receive
12 I(b) Indication
13 S(b) Signal element timing
14 B(b)/X(b) Byte timing: Modem transmit signal
15 Future use Future use
NOTES:
1 Assigned for connecting the shields between tandem sections of shielded interface cables.
2 (a) and (b) indicate pins that are associated to form pairs.
G - Signal ground (or common return) In the case of interchange circuits according to Recommendation V.11, it interconnects the zero volt reference points of a generator and a receiver to reduce environmental signal interference, if required.
T - Transmit The binary signals originated by the system to be transmitted during the data transfer phase by way of the data circuit to one or more remote systems are transferred on this circuit to the modem.
This circuit also transfers the call control signals originated by the system to be transmitted to the modem in the call establishment and other call control phases as specified by the relevant recommendations for the procedural characteristics of the interface.
                         
The modem monitors this circuit to detect electrical circuit fault conditions, according to the specifications of the electrical characteristics of the interface. A circuit fault is interpreted by the modem as defined in the recommendation for the procedural characteristics of the interface.
                         
R - Receive The binary signals sent by the modem as received during the data transfer phase from a remote system are transferred on this circuit to the system.
This circuit also transfers the call control signals sent by the modem as received during the call establishment and other call control phases specified by the relevant recommendation for the procedural characteristics of the interface.
                         
The system monitors this circuit to detect electrical circuit fault conditions, according to the specifications of the electrical characteristics of the interface. A circuit fault is to be interpreted by the system as defined in the recommendations for the procedural characteristics of the interface.
                         
C - Control Signals on this circuit control the modem for a particular signalling process.
Representation of a control signal requires additional coding of circuit T-Transmit as specified in the relevant recommendation for the procedural characteristics of the interface. During the data phase, this circuit must remain on. During the call control phases, the condition of this circuit must be as specified in the relevant recommendation for the procedural characteristics of the interface.
                         
The modem monitors this circuit to detect electrical circuit fault conditions, according to the specifications of the electrical characteristics of the interface. A circuit fault is to be interpreted by the modem as defined in the recommendation for the procedural characteristics of the interface.
                         
I - Indication Signals on this circuit indicate the state of the call control process.
Representation of a control signal requires additional coding of circuit R-Receive, as specified in the relevant recommendation for the procedural characteristics of the interface. The on condition of this circuit signifies that signals on circuit R contain information from the distant system. The off condition signifies a control signalling condition which is defined by the bit sequence on circuit R as specified by the procedural characteristics of the interface.
                         
The system monitors this circuit to detect electrical circuit fault conditions, according to the specifications of the electrical characteristics of the interface. A circuit fault is to be interpreted as defined in the recommendation for the procedural characteristics of the interface.
                         
S - Signal element timing Signals on this circuit provide the system with signal element timing information from the modem. The condition of this circuit is on and off for nominally equal periods of time. However, for burst asynchronous operations, longer periods of off condition may be permitted equal to an integer odd number of the nominal period of the on condition as specified by the relevant procedural characteristics of the interface.
The system must present a binary signal on circuit T-Transmit and a condition on circuit C-Control, in which the transitions nominally occur prior to the transitions from off to on condition of this circuit.
                         
The modem presents a binary signal on circuit R-Receive and a condition on circuit I-Indication in which the transitions nominally occur at the time of the transitions from off to on condition of this circuit.
                         
The modem transfers signal-element timing information on this circuit across the interface whenever the timing source is capable of generating this information.
                         

V.24/X.21bis Pin Assignments

The following table describes V.24/X.21bis pin assignment for a 25-pin connector (for speeds up to 20 Kbps).

V.24/X.21bis Pin Assignments for a 25-Pin Connector
Pin CCITT Circuit CCITT Circuit Designation
1

2 103 Transmitted data
3 104 Received data
4 105 Request to send
5 106 Ready for sending
6 107 Data set ready
7 102 Signal ground
8 109 N
9 - N
10 - N
11 - N
12 - N
13 - F
14 - F
15 114 Tx signal element timing from modem
16 - F
17 115 Rx signal element timing from modem
18 141 Local loopback
19 - F
20 108 Data terminal ready: Connect data set to line
21 140 Local loopback
22 125 Calling indicator
23 - N
24 - F
25 142 Test indicator
Notes: N=Pin permanently reserved for national use. F=Pin reserved for future international standard and should not be used for national use.

V.35/X.21bis Pin Assignments

The following table describes the V.35/X.21bis pin assignments for a 34-pin connector ( for speeds above 20 kbps).

V.35/X.21bis Pin Assignments for a 34-Pin Connector
Pin CCITT Circuit CCITT Circuit Designation Direction
A


B 102 Signal ground or common return Common
C 105 Request to send From system
D 106 Ready for sending To system
E 107 Data set ready To system
F 109 Data channel received line signal detection To system
H 108.1 Connect data set to line From system
H 108.2 Data terminal ready From system
J 125 Calling indicator To system
K 141 Local loopback From system
L - F -
M - F -
N 140 Loopback/Maintenance test From system
P 103 Transmitted data A-wire From system
R 104 Received data A-wire To system
S 103 Transmitted data B-wire From system
T 104 Received data B-wire To system
U 113 Tx signal element timing from system A-wire From system
V 115 Receiver signal element timing A-wire To system
W 113 Tx signal element timing from system B-wire From system
X 115 Receiver signal element timing B-wire To system
Y 114 Tx signal element timing from modem A-wire To system
Z - F -
AA 114 Tx signal element timing from modem B-wire To system
BB - F -
CC - F -
DD - F -
EE - F -
FF - F -
HH - N -
JJ - N -
KK - N -
LL - N -
MM - F -
NN 142 Test indicator To system
Notes: N=Pin permanently reserved for national use. F=Pin reserved for future international standard and should not be used for national use.

V.36 Pin Assignments

The following table describes the V.36 pin assignments for a 37-pin connector:

ARTIC960 6-Port V.36 37-Pin D-Shell Connector Pins
Pin CCITT Circuit Signal Name Direction
04 103 TXDnA From system
22 103 TXDnB From system
06 104 RXDnA To system
24 104 RXDnB To system
05 114 TCLKInA To system
23 114 TCLKInB To system
08 115 RCLKInA To system
26 115 RCLKInB To system
17 113 TCLKOnA From system
35 113 TCLKOnB From system
07 105 RTSn From system
09 106 CTSn To system
13 109 DCDn To system
12 108.2 DTRn From system
11 107 DSRn To system
19 102 SigGnd(-)
01 -- Shield(-)
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