RAD Data comm ASMi-31 Manuale Utente

X.21 Connectors

C-1

Appendix C
X.21 Interface Module

C.1 General

IR-X.21 is an interface module for RAD modems, converting X.21 signals to
TTL levels. The converted data is sent over the modem link, using the
modem modulation technique, and is converted back at the other end into
X.21 signals, or into any other digital interface signal.
ASMi-31 is generally supplied with IR-X.21. This is due to an internal FIFO
that assumes the phase mismatch when the clock is supplied by an external
source. ASMi-31 also has the option to order IR-X.21 for extra buffers.
Figure C-1 shows a typical application of the ASMi-31 standalone modem
with the IR-X.21 interface module.

Figure C-1 Typical ASMi-31 X.21 Application

C.2 X.21 Connectors

Figure C-2 shows the rear panel of a standalone ASMi-31 with the
IR-X.21 interface module.

Line Connector

Figure C-2 ASMi-31 Rear Panel with X.21 Connector

The ASMi-31 modem rack version requires an additional adaptor 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 for the
CIA/V.35 attachment in Chapter 5.

Order from: Cutter Networks

Ph:727-398-5252/Fax:727-397-9610