GE 90-70 manual CPU Configuration Parameters, Program Folders in Logicmaster

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Program Folders in Logicmaster 90

With the Logicmaster programming software, there must be different folders for each configuration. If the logic is identical for both PLCs, a third folder could be used for the logic and reference tables. This results in three folders for the system.

Folder A - configuration for the Primary unit.

Folder B - configuration for the Secondary unit.

Folder C - logic and reference tables for both systems.

CPU Configuration Parameters

When configuring a system for Hot Standby CPU Redundancy, the following additional parameters must be set up.

Parameter	Default	Choices	Description / Comment
I/O Scan Stop	Must be set to NO
Watchdog	200ms	10ms to	The value selected should allow for the expected
Timer		1000ms	scan plus two fail wait times.
Redund	Primary	Primary,	Whether the CPU being configured is the Primary or
Type		Secondary	Secondary CPU in the Redundancy system. One
			configuration must be set to Primary; the other to
			Secondary.
Background	5ms in limited	0ms to	The background window runs several diagnostic tests
Timer	window mode	255ms	that can be disabled by setting the timer to 0ms.
			These tests are run in Constant Window and
			Constant Sweep mode only if the window/sweep
			time is large enough.
Fail-wait	60ms	60ms to	The time one PLC will wait on one Redundancy
		400ms	Communications Module 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.
			Storing configuration to either unit could also
			recover the RCM links.
Control	GHS (CPU780)	GHS or	Genius Hot Standby (GHS) or
Strategy	GDB (CGR772,	GDB	Genius Dual Bus (GDB).
	CGR935)
Shared I/O	The references within the control of the Redundancy system. See the following
References	paragraphs for more information. The Shared I/O selections must match exactly
	between Primary and Secondary PLCs.
Fault		Fatal,	Fault actions when the CPUs are not synchronized
Category		Diagnostic	can be configured to select a safe shutdown or fault
(configurable			tolerant operation in case a failure occurs with no
when not			backup ready.
synchronized
only)

3-2 Series 90™-70 Enhanced Hot Standby CPU Redundancy User's Guide – May 2000 GFK-1527A