Comtech EF Data CRS-200 - Manual (Page 35)

CRS-200 Redundancy Switch Setup Guide
Rev. 1 6–3
6.1.3 Remote Control
With power applied to all modems, it is important to set all their remote interfaces to
RS232 with a baudrate of 9600. This is the default configuration for all Comtech EFData
modems. All modems remain at address 0000 because the switch communicates with the
desired modem via hardware. This connection is made on the 25-pin cable using pins that
are not used by the terrestrial data paths. Because the remote link for all the modems is
accomplished through the 25-pin cables, it is important to leave the 9-pin remote
connectors unplugged to avoid contention.
IMPORTANT REMINDER:
SET THE REMOTE CONTROL INTERFACE ON ALL OF THE MODEMS IN THE REDUNDANCY
GROUP TO RS232, 9600 BAUD
THE REDUNDANT MODEM MUST BE IN REMOTE MODE
THE TRAFFIC MODEMS CAN BE IN LOCAL OR REMOTE MODE (PUT INTO REMOTE MODE
IF REMOTE M&C THROUGH THE SWITCH IS REQUIRED)
DO NOT BE CONCERNED THAT ALL THE MODEMS ARE SET TO ADDRESS 0000 - THE
SWITCH TRANSLATES ADDRESSES AND PASSES COMMANDS TO THE CORRECT MODEMS
Next, set the redundant modem to remote mode. The traffic modems may be left in local
or remote mode, depending on how the user wishes to communicate with them, but the
redundant modem must always be set to remote mode. This is because the switch must
always be able to control its configuration. A failure by the switch to control the
redundant modem remotely is considered a fault condition.
6.1.4 Modem Alarms
In addition to the remote link, the 25-pin cable also carries the modem’s alarm relay
outputs, which are repeated on the 15-pin alarm connector. An input line, “External
Carrier Off”, is also present on both connectors. Since this input is used by the switch to
control the modems’ IF carriers by driving this line, it is recommended that the 15-pin
port on the modem should be used with caution.