Operating instructions

RCS20 M:N Redundancy Switch Operation
TM056 - Rev. 2.3 3-1
Section 3 – Operation
3.0 Principles of Operation
This chapter provides additional basic information on the RCU20 and IFS20 hardware and internal
operation.
3.1 RCS20 Major Assemblies
The RCU20 Redundancy Control Unit contains the modules that control and monitor the operation of
the M:N Switch System. The RCU20 is composed of the following major assemblies and
components:
1. Central Processor Unit (CPU) Board
2. Front Panel Board
3. Controller Interface Module
4. Clock Distribution Module (optional)
5. Dual Redundant Power Supplies
6. Ethernet Module (optional)
7. Bank Control Module
3.1.1 Central Processing Unit (CPU) Board
The Central Processor Unit (CPU) Board contains the M:N Switch intelligence and memory
circuitry. The on-board microprocessor is an MC68302, which has a 24-bit address bus and a 16-
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.
3.2 Redundant Power Supplies
The M:N Switch comes equipped with two fully redundant internal power supplies (PS1 and PS2)
that supply DC voltage 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. Only if the voltage output failed on both supplies would the Switch become
inoperative. PS1 and PS2 are located one on either side of the RCS20.
3.3 RCU20 Rear Panel
As previously shown in Figure 2-1, the RCS20 contains the plug-in slots for the Interface Control
Module, the Clock Distribution Modules, Bank Control Modules and Ethernet modules. Also
contained in the back panel are the two AC fuses and power receptacles.