Appendix C. IR- X.21B Interface Module ASM-20 Installation and Operation Manual
C-2 IR-X.21B Interface Module 6/4/99 13:18
C.3 IR-X.21B Connectors
Figure C-2 shows the rear panel of a standalone ASM-20 with the IR-X.21B
interface module.
DTE
X21
Line Connector
Figure C-2 ASM-20 Rear Panel with X.21 Connector
The ASM-20 modem rack version requires an additional adapter to connect
between the DB-15 connector of the X.21 equipment to the DB-25
connector of the ASM-MN-214 modem rack. For this purpose, an optional
DB-15 attachment CIA/X.21 can be ordered separately from RAD. The
attachment connects to the ASM-MN-214 rear panel as shown in Figure 5-3
for the CIA/V.35 attachment.
Pin Assignment Table C-1 shows the X.21 DB-15 pin assignment.
Table C-1 IR-X.21B DB-15 (RS-422) Connector Pin Assignment
Pin ID Function
1 Shield Chassis connection
2 A Transmit signal A
3 A Control A
4 A Receive A
5 A Indication A
6 A Signal timing A
7 A External Timing
8 GND Common
9 B Transmit B
10 B Control B
11 B Receive B
12 B Indication B
13 B Signal Timing B
14 B External Timing