Comtech EF Data RCS11 - Manual (Page 27)

RCS11 1:1 Redundancy Switch Theory of Operation
MN-RCS11 – Revision 9 2–3
2.3.1 Main Switch Board
The Main Switch Board contains the RCS11 1:1 Switch Intelligence and Memory Circuitry and all
switching circuitry. The on-board microprocessor is an MC68HC11, which has a 16-bit address
bus and an 8-bit data bus. The microprocessor controls and coordinates all of the major
functions of the Switch and performs all necessary calculations. The non-volatile system memory
on the board stores the switching parameter settings for each modem channel. Control and data
signals are routed to the appropriate devices in the system through various latches and
transceivers that are controlled by the microprocessor.
2.3.2 Front Panel Board
The Front Panel Board contains the LED Indicators and the pushbutton switches needed to
control and operate the RCS11. Refer to Figure 3.0 for a description of Front Panel Indicators.
2.3.3 Redundant Power Supplies
The 1:1 Switch comes equipped with two fully redundant internal power supplies (PS1 and PS2)
that supplies power to the system. Each supply is fully independent of the other, including their
source of AC power and fusing.
The Switch can remain fully operational as long as it is supplied with a source of voltage from
either power supply. PS1 and PS2 are located one on either side at the rear of RCS11 chassis.
2.4 RCS11 General Operation
2.4.1 Signals
All necessary Modem signals are backed-up through a passive switching system. Signals that
are required to maintain the modem in off-line (hot-standby) are buffered by appropriate circuitry
to minimize loading on incoming signals.
2.4.2 Backup
If an online MOD fault is sensed, and the off-line MOD is in a non-faulted state, the RCS11 will
switch to the MOD without the fault. The Fault Signal has a small debounce delay to prevent
false triggering. If the faulted MOD has its fault cleared, it stays off-line unless the other MOD
has subsequently faulted. The DEMOD faults are handled in a similar manner, but the fault
signals have longer debounce delays to allow for Demodulator acquisition time.