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RCS11 1:1 Redundancy Switch Principles of Operation
TM061 Rev. 1.3 Page 5-1
Section 5 - Principles of Operation
5.0 Principles of Operation
This chapter provides additional basic information on the RCS11.
5.1 RCS11 Major Assemblies
The RCS11 Redundancy Control Unit contains the modules that control and monitor the
operation of the 1:1 Switch system. The 1:1 Switch is composed of the following major
assemblies and components:
1. Main Switch Board.
2. Front Panel Board.
3. Dual Redundant Power Supplies.
5.1.1 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 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.
5.1.2 Front Panel Board
The Front Panel Board contains the LED indicators and the pushbutton switches needed to
control and operate the RCS11.
5.1.3 Redundant Power Supplies
The 1:1 Switch comes equipped with two fully-redundant internal power supplies (PS1 and PS2)
that 5 volts 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 front of RCS11 chassis.
5.2 RCS11 General Operation
5.2.1 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.
5.2.2 Backup
If an online MOD fault is sensed, and the off-line MOD is not also faulted, 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.