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36 Series 90-70 Hot Standby CPU Redundancy User’s Guide – December 1993
GFK-0827
set for SIMPLEX mode. The parameters on this screen are Ctrl Strgy (Control Strategy),
Fail Wait and SHARED I/O.
Ctrl Strgy
This parameter specifies which type of control strategy is selected for a redundancy
system. The valid entry is three ASCII characters (A...Z). The only value that is
supported at this time is Genius Hot Standby (GHS). If this parameter is set to any other
value, the configuration will be considered valid, but any attempt to STORE the
configuration will be rejected by the PLC. The default value is GHS.
Fail Wait
This parameter specifies the time one PLC will wait on one RCM link for the other PLC
to respond before faulting that link. The Fail Wait range is 60 msec to 400 msec
(measured in multiples of 10 msec) with the default value being 60 msec. The following
table lists the two parameters described above.
Parameter Description Valid Values Default Value
Fail Wait Wait time 60 to 400 milliseconds in
10 millisecond increments
60
Control Strategy Three character control
strategy identifier
A......Z GHS
Shared I/O
The Shared I/O values are the reference addresses and ranges for the I/O references
included in the 20 KBytes of Input data (%I, %AI) and 28 KBytes of Output data (%Q,
%AQ, %M, %R) which is shared between the Primary and the Secondary units in the
Hot Standby CPU Redundancy control system. The Shared I/O data is transferred from
the active CPU to the backup CPU each sweep (refer to Chapter 4, ”Synchronous Scan”,
for details). The valid entries for these parameters are described in the following tables.