GE 90-30/20/Micro manual Fault Handling, Fault Class Examples

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Section 1: Fault Handling

Note

This information on fault handling applies to systems programmed using

Logicmaster 90-30/20/Micro software.

Faults occur in the Series 90-30 , 90-20, or Series 90 Micro PLC system when certain failures or conditions happen which affect the operation and performance of the system. These conditions, such as the loss of an I/O module or rack, may affect the ability of the PLC to control a machine or process. These conditions may also have beneficial effects, such as when a new module comes online and is now available for use. Or, these conditions may only act as an alert, such as a low battery signal which indicates that the battery protecting the memory needs to be changed.

Alarm Processor

The condition or failure itself is called a fault. When a fault is received and processed by the CPU, it is called an alarm. The software in the CPU which handles these conditions is called the Alarm Processor. The interface to the user for the Alarm Processor is through the programming software. Any detected fault is recorded in a fault table and displayed on either the PLC fault table screen or the I/O fault table screen, as applicable.

Classes of Faults

The Series 90-30, 90-20, and Micro PLCs detect several classes of faults. These include internal failures, external failures, and operational failures.

Fault Class

Examples

Internal Failures	Non-responding modules.
	Low battery condition.
	Memory checksum errors.
External I/O Failures	Loss of rack or module.
	Addition of rack or module.
Operational Failures	Communication failures.
	Configuration failures.
	Password access failures.

3-2 Series 90-30/20/Micro Programmable Controllers Reference Manual–September 1998 GFK-0467K