RAD Data comm ASM-20 - Manual (Page 60)

Appendix C IR-X.21B Interface Module ASM-20 Installation and Operation Manual
C-2 IR-X.21B Interface Module
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
C.3 IR-X.21B Interface Module
The IR-X.21B interface module is shown in Figure C-3 . It has two operation modes
which are selectable on the PCB board. The selection is made by means of the JP2
jumper located within the module as shown in the figure. The EXT mode is
described on page C-3 and illustrated in Figure C-4 . The INT/RCV mode is
described on page C-4 and illustrated in Figure C-5 .
The X.21 interface should be in accordance with the modem clock mode. For
example, if the modem is in the EXT mode, then JP2 should be set to the EXT
position.
Note