Black Box MT720A-35T Manual De Usuario

The Fradswitch has three connectors located on the rear panel that serve the X.25 links, 
and RJ-45 connectors located on the front panel for the asynchronous data channels.

Fradswitch channel interfaces are configured as data communication equipment (DCE) interfaces, thereby
allowing direct connection, via RS-232 port cables, to data terminal equipment (DTE). When modems are
used to extend the range (tail-end circuits), cross-over cables are required. Channel interfaces are
asynchronous, so clock signals are not supported or required.

in the Packet Switching Guide lists pin allocation in Fradswitch series data-channel connectors,

and provides typical wiring diagrams for straight-through and cross-over cables.

Fradswitch X.25 link interfaces are configured as DTE interfaces, intended for connection to synchronous
modems that are capable of providing the clock signals that determine the Fradswitch’s X.25 link data rate.
The X.25 link connectors type depends on the Fradswitch interface:

• RS-232/V24:

25-pin D-type, female connector

• X.21:

15-pin, female connector

• V.35:

34-pin, female connector

Appendix A in the Packet Switching Guide provides the pin allocations for the various X.25 links connectors.