Comtech EF Data RAP-100 - Manual (Page 15)

Redundant CSAT Control RAP-100 Remote Access Panel
2–2 Rev. 1
There are a few important points to be made about this system architecture. First, the
Redundancy Controller Box is in complete control of the transfer switches (both Tx and
Rx) when the system is in AUTO mode. This means that the Redundancy Controller Box
is always monitoring the status of both CSATs via their Summary Fault Relays and will
change the position of the switches if the ONLINE unit fails.
If the OFFLINE unit is also failed, the Redundancy Controller Box will not change
the switch position.
The second point is the operator can force a change in the switch position via either a
serial command to the Redundancy Controller Box or by shorting the appropriate pins on
the interface connector. Again this assumes that both unit are non-failed.
The third point is that if the operator commands the Redundancy Controller Box to
MANUAL mode, subsequent ‘Switch Position’ commands will always cause the transfer
switches to change position independent of the status of the CSATs (failed or non-failed).
The fourth point is that when the Redundancy Controller Box is in MANUAL mode it
does not automatically switch the position of the Tx and Rx transfer switches when the
ONLINE unit fails.
The final important point to be made is that the RAP-100 monitors and controls the
redundant system using only serial commands sent via the 4-wire RS-485 interface.