Filter
Top Products
3
section level 1 1
figure bi level 1
table_big level 1
27
GFK-0827
Chapter 3 Configuration
This chapter describes how to configure a Series 90-70 PLC system for Hot Standby CPU
Redundancy. Several parameters in addition to the normally configured CPU
parameters must be configured for the Redundancy CPU 780. A description of all of the
parameters for a redundancy system is provided first, followed by an example of a
Primary system configuration and a Secondary system configuration.
Configuring a Hot Standby CPU Redundancy System
As discussed previously, when configuring a system for Hot Standby CPU Redundancy,
the following parameters require configuration in addition to the CPU configuration
parameters that are done for any other CPU78X CPU.
Configuration
Parameter Description
Fail-wait The time one PLC will wait on one RCM link for the other
PLC to respond before faulting that link. The CPU will try
both links before continuing its scan. Once the RCM links are
marked as failed, one unit or the other must be power cycled
to recover them. Range is 60 ms to 400 ms, with the default
value being 60 ms.
Control Strategy The control strategy for the current configuration. Config-
ured as a three-character identifier (GHS for Hot Standby
CPU Redundancy). The default value is GHS (currently the
only value that is valid).
Shared I/O References The references within the control of the Redundancy system;
limited to total of 20 KBytes for Inputs and 28 Kbytes for Out-
puts. The references which may be used as shared I/O are
%I, %Q, %AI, %AQ, %R, and %M. .
Redund Type Whether the CPU being configured is the Primary or Second-
ary CPU in the Redundancy system. Redund Type has three
possible values: PRIMARY, SECONDARY, or SIMPLEX. SIM-
PLEX indicates a non-redundant system. The default value is
PRIMARY. SIMPLEX is not a currently supported Redund Type
for the CPU 780.