Comtech EF Data CRS-200 - Manual (Page 34)

Setup Guide CRS-200 Redundancy Switch
6–2 Rev. 1
6.1 25-Pin Data Cables
First, connect all 25-pin cables between the modems and their appropriate TMI or RMI
cards. It is important that all modems be of the same model number and software revision
so that the redundant modem can properly mimic all traffic modems. If there are unused
positions on the switch, remove any unused TMI cards and replace with a blank plate.
6.1.1 Physical Cable Requirements
The 25-pin cables required between each modem and its plug-in card (TMI or RMI)
should be of shielded, twisted-pair construction with the grounded shield bonded to the
back-shell. All 25 pins should be wired to the same pin number at either connector (pin-
to-pin), with a male connector at one end and female at the other (SEE CABLES
SECTION). The modem accepts the male end of the cable while the TMI or RMI accepts
the female end into the port labeled “To Traffic Modem” or “To Redundant Modem”.
Depending upon the location of each modem in the rack, a length of from 2 to 5 feet is
desirable. Appropriate data cables are available from Comtech EFData, so please consult
the factory for ordering information. Please note that these cables are an extra-cost item.
WARNING
ALWAYS KEEP THE 25-PIN CABLE ATTACHED TO AN OPERATING SWITCH WHILE POWER
IS SUPPLIED TO THE MODEM.
If a modem is added to an operating 1:N system, attach its cable before applying power. If a modem is
removed, turn off power first, then remove its 25-pin cable. This allows the switch to always have control
of a modem’s Tx carrier, and prevent contention in the system.
6.1.2 External Data Connection
When each cable is connected between the modem and its plug-in card, the user’s
terrestrial data connection to the external router, multiplexing equipment or test data
generator should be made to the female connector on the TMI labeled “User Data
Interface”. This replaces the direct connection to the traffic modem’s “Data Interface”
port. Note that the RMI does not have this connector, as the redundant modem’s function
is to replace a faulted traffic modem. Even with the switch turned off, this should
complete the terrestrial data paths between each traffic modem and its external equipment
so that the modems may now be switched on.
NOTE TO USERS OF THE CIC-50: If a modem requires Comtech’s optional G.703
Interface Converter, the CIC-50, the device must plug into the TMI’s “User Data
Interface” port, rather than directly to the rear of the modem. Unfortunately, space
limitations require that another 25-pin cable be attached between the TMI and the CIC-
50. The redundant modem does not require its own converter.