5

Diagnostics in a GMR System

In a GMR system, extensive diagnostic capabilities are provided by standard Genius I/O diagnostics and by the special autotesting and discrepancy reporting features of the GMR software. Standard Genius diagnostics, which are covered in other books, are not described in detail here.

Each PLC provides a full range of fault table and program access to fault information.

Input Diagnostics

HGeniusDiagnostics:

hLine fault. a feature of the 16-circuit DC blocks. To report line faults, an input must be configured for tristate operation and installed as explained on page 5-14.

For blocks in GMR mode, a line fault represents a short circuit fault on the field wiring.

For blocks in any other mode, a line fault represents an open circuit fault in the field wiring.

HAutotestDiagnostics. for discrete inputs configured for autotesting., autotesting determines whether inputs can attain their opposite state (alarm state) and checks for channel to channel shorts.

HDiscrepancyReporting: between the raw input data from each bus and the corresponding voted inputs.

Output Diagnostics

HGeniusDiagnostics:

hNo-loadfault:For 16-circuit blocks only, individual outputs can be configured to enable or disable reporting No-load faults. The minimum load current required to assure proper no-load reporting is 100mA (not 50mA, as it would be for a block not used in a GMR group). For an individual block:

If outputs are On with no output load, no-load fault reports may be generated at any time except during a Pulse Test.

If outputs are Off with no output load, no-load fault reports are generated during a Pulse Test.

hShortcircuit fault.

hOvertemperaturefault.

hOverloadfault

hFailedswitch:. Occurs if the actual output state differs from the commanded state.

HAutotestDiagnostics. for discrete outputs configured for autotesting. Autotesting determines whether outputs can attain the opposite of their normal state.

HOutputDiscrepancyReporting: Blocks configured for GMR mode operation report to each PLC the discrepancy status for the data from each PLC, together with each PLC'sonline/offlinestatus.

5-2

GeniustModular Redundancy Flexible Triple Modular Redundant (TMR) System

GFK-0787B

 

User's Manual ±March 1995

 

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Image 62
GE GFK-0787B user manual Diagnostics in a GMR System, Input Diagnostics, Output Diagnostics