Because RFL™ and Hubbell® have a policy of continuous product improvement, we reserve the right to change designs and specifications without notice.
The SWITCH parameter unconditionally forces the Main or Standby Module to become active, if not
overridden by the front-panel mode slide switch. It will even take effect if the selected module does not
exist, therefore it should be used with care.
A variation of the forced-switch scheme is implemented by means of the MAIN ON/OFF parameter.
Setting MAIN=OFF forces the Main Module to report an equivalent of on-board trouble to the
monitoring Standby Module.
Then, if a Standby Module detects no trouble of its own, and if it is allowed to perform automatic
switchover, it will become active.
Since this method utilizes the automatic switchover mechanism, it is non-revertive. Setting MAIN=ON
merely stops reporting a fictitious trouble state, but Standby Module will remain active.
The MAIN parameter should be used with great care. In particular, when returning the Main Module to
the active state with this method, first command should result in, and only then SWITCH=MAIN
should be issued. Otherwise, flip-flopping of the system could result.
The difference between the SWITCH and MAIN parameters is that SWITCH forcibly causes a swap
without regard to any other redundant operation rules. The MAIN parameter, on the other hand,
simulates an on-board failure and allows the normal automatic swap process to run its course.
Finally, it is important to remember that all controlling methods must be individually returned to
AUTO for automatic operation. This includes both the front-panel mode slide switch and the SWITCH
configuration parameter, as well as MAIN=ON.
IMUX 2000E1 RFL Electronics Inc.
January 23, 2004 3-11 (973) 334-3100
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