ELSA GmbH Aachen
Handbuch ELSA TanGo 1000
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V.24 interface
 

The interface between the ISDN terminal adapter and the computer consists of a variety of data, control and signaling lines. The condition of most of the interface lines is displayed by LEDs on the front of the unit.
The pin assignment of the V.24 interface for 9-pin or 25-pin connectors is as follows:

9-pin

25-pin

DIN

ITU-T

USA

Designation (USA) Designation (Germany), direction
U* 1 E1 101 GND Protective Ground Schutzerde -
5 7 E2 102 GND Signal Ground Betriebserde -
3 2 D1 103 TxD Transmit Data Sendedaten   ISDN-Adapter
2 3 D2 104 RxD Receive Data Empfangsdaten   ISDN-Adapter
6 6 M1 107 DSR Data Set Ready Betriebsbereitschaft   ISDN-Adapter
8 5 M2 106 CTS Clear to Send Sendebereitschaft   ISDN-Adapter
9 22 M3 125 RI Ring Indicator Ankommender Ruf   ISDN-Adapter
1 8 M5 109 DCD Data Carrier Detect Empfangssignalpegel   ISDN-Adapter
4 20 S1 108 DTR Data Terminal Ready DEE betriebsbereit   ISDN-Adapter
7 4 S2 105 RTS Request to Send Sendeteil anschalten   ISDN-Adapter

U = Housing/shield

 

NOTE

The designations in the table name the functions of the lines (e.g. transmission data) as related to the data terminal (computer).

 

The interface lines have the following significance:
Computer/terminal operational - DTR = Data Terminal Ready

The effect of this control line on the ISDN terminal adapter is determined by the command AT&D.

Switch on transmission - RTS = Request To Send

Operational DSR = Data Set Ready

This signal line is normally always active (ON), but is influenced by the commands AT\D and AT&S.

Clear to send CTS = Clear To Send

This output is normally always active (ON), but is influenced by the commands AT\D, AT\Q and AT&R.

Incoming call RI = Ring Indicator

This ISDN terminal adapter output becomes active (ON) when the adapter detects an incoming call (see also command ATA). Incoming calls are detected only if the DTR control line is active (ON) or the command AT&D0 has been issued.

Connection DCD = Data Carrier Detect

This ISDN terminal adapter output normally becomes active (ON) when the adapter has established a valid connection.

Copyright © 1997 ELSA GmbH, Aachen (Germany)