RFL IMUX 2000 - ; 3.1.2 SYSTEM MONITORING FOR REDUNDANT MODE.; 3.1.3 OPERATING PRINCIPLES OF REDUNDANT MODE.

Because RFL™ and Hubbell® have a policy of continuous product improvement, we reserve the right to change designs and specifications without notice.
3.1.2 SYSTEM MONITORING FOR REDUNDANT MODE.
Several backplane and on-board signals are monitored in order to detect Common Module failure.
These include:
• Bus Timing & Synchronization (for each bus driven by monitored module).
• SCB Sync & Data (if driven by monitored module).
• On-board clocks.
• Microprocessor activity.
• Framer Received Carrier Loss and Loss of Sync.
Most signals are monitored for their presence or for frequency deviations above a certain limit. More
critical signals, such as clocks and overhead pulses are checked against a minimum and maximum
frequency range.
3.1.3 OPERATING PRINCIPLES OF REDUNDANT MODE.
Redundant Mode Protection is based on the following principles: (Also refer to the functional block
diagram shown in Figure 3-2)
• All CM4 modules are identical, allowing them to be used interchangeably for any multiplexer
function.
• The communication function is determined by settings on the Redundant Module Adapter.
These settings select Terminal, DI-A or DI-B.
• The redundant application is controlled by slot position. Depending on the slot it is plugged
into, a CM4 will become Main Module or a Standby Module.
• The Main Module is the default active device under normal conditions. The Standby Module is
used for protecting the Main Module. When a fault is detected, the Main Module is deactivated
and the Standby module is activated. While active, either module performs the same functions
with respect to communications (E1 and DS0 traffic) and shelf control (control and monitoring
of channel modules).
• The module located in the Standby slot controls all Redundant Mode operation. The Main
module monitors its own on-board state, but does not perform any actions related to switching
between the Main and Standby Modules. The Standby Module makes all decisions and
performs all actions.
• The Standby Module will perform automatic swap from Main to Standby if permitted by the
AUTO settings position of the front-panel mode slide switch and by software configuration
parameters. This automatic swap process is non-revertive and will not activate a Main module.
• The Standby Module will activate either the Main or Standby Common Module when forced by
settings on the front-panel mode slide switch, or by software configuration parameters.
• The CM4 Main/Standby pairs in a Drop-and-Insert are independent. The state and actions of
one pair does not affect the other pair.
IMUX 2000E1 RFL Electronics Inc.
January 23, 2004 3-2 (973) 334-3100