GE 90-30/20/Micro manual Fault Reference Definitions, Side Effect Description

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Fault Reference Definitions

The alarm processor maintains the states of the 128 system discrete bits in %S memory. These fault references can be used to indicate where a fault has occurred and what type of fault it is. Fault references are assigned to %S, %SA, %SB, and %SC memory, and they each have a nickname. These references are available for use in the application program as required. Refer to Chapter 2, “System Operation,” for a list of the system status references.

Additional Fault Effects

Two faults described previously have additional effects associated with them. These are described in the following table.

Side Effect	Description
PLC CPU Software Failure	Whenever a PLC CPU software failure is logged, the Series 90-30 or
	90-20 CPU immediately transitions into a special ERROR SWEEP
	mode. No activity is permitted in this mode. The only method of
	clearing this condition is to reset the PLC by cycling power.
PLC Sequence Store Failure	During a sequence store (a store of program blocks and other data
	preceded with the special Start-of-Sequence command and ending with
	the End-of-Sequence command), if communications with the
	programming device performing the store is interrupted or any other
	failure occurs which terminates the download, the PLC Sequence Store
	Failure fault is logged. As long as this fault is present in the system,
	the PLC will not transition to RUN mode.

PLC Fault Table Display

The PLC Fault Table screen displays PLC faults such as password violations, PLC/configuration mismatches, parity errors, and communications errors.

The programming software may be in any operating mode. If the programming software is in OFFLINE mode, no faults are displayed. In ONLINE or MONITOR mode, PLC fault data is displayed. In ONLINE mode, faults can be cleared (this may be password protected).

Once cleared, faults which are still present are not logged again in the table (except for the “Low Battery” fault).

I/O Fault Table Display

The I/O Fault Table screen displays I/O faults such as circuit faults, address conflicts, forced circuits, and I/O bus faults.

GFK-0467K Chapter 3 Fault Explanation and Correction 3-5