State Industries GFK-0827 manual Programming Considerations, Configuration Requirements

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Programming Considerations

There are several features in the operation of the Redundancy CPU which are not supported or are different then operation of other CPUs. These features are listed below and are described in detail in Chapter 4, ºSystem Operationº.

The following features are not available with the Redundancy CPU (CPU 780):

HI/OInterrupts

HTimed Interrupts

HVME Integrator Rack

HSTOP/IOSCAN mode

HFlash memory operation

The operation of the following features is different with the CPU 780 than with other

Series 90-70 CPUs:

HRUN/DISABLEDmode

HConfiguration of fault actions

HSTOP to RUN mode

HDefault Background Window Time

Configuration Requirements

The Redundancy CPU and the Redundancy Communications Module must be configured into the redundancy system. There are several additional parameters (other than the normal CPU parameters) that must be configured with the Logicmaster 90-70 Configurator function which are unique to the Hot Standby CPU Redundancy system. The following items require configuration when specifying the CPU 780 (the Redundancy CPU) as the CPU for configuration:

		Configuration
		Parameter	Description
		Fail-wait(60 ms to 400 ms)	The time to wait on a failed active PLC before switching to
			the backup CPU. The default value is 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 sys-
			tem; up to 20 KBytes of Input data and 28 KBytes of Out-
			put data is transferred. 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 Sec-
			ondary CPU in the Redundancy system. Redund Type
			has three possible values: PRIMARY, SECONDARY, or
			SIMPLEX. SIMPLEX (not supported in this release of the
			product) indicates a non±redundant system. The default
			value is PRIMARY.
10	Series 90-70 Hot Standby CPU Redundancy User's Guide ± December 1993			GFK-0827