GE 90-70 manual Faulting the Redundancy Communications Module, Losing a Link

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Faulting RCMs, Losing Links, and Terminating Communications

There are distinct differences between losing a redundant communications link and faulting an RCM.

Faulting the Redundancy Communications Module

Faulting the Redundancy Communications Module occurs only when a hardware-related failure such as a parity error or VME bus error exists.

The following actions are taken when a Redundancy Communications Module is faulted:

1.Loss of Module fault is logged in the PLC Fault Table.

2.All LEDs on the Redundancy Communications Module are turned OFF. The LEDs on the other Redundancy Communications Module continue to be updated as long as that RCM is OK.

3.The module fault contact is set. If the failed Redundancy Communications Module is in the local main rack, then the SLOT_0X fault contact is set (X is the slot number for the Redundancy Communications Module). If the failed RCM is in the other unit's main rack, then the SLOT_71 fault contact is set.

4.The corresponding communications link is no longer used. If the other link is still operating, that link is used for all further data transfer, and the units can remain in synchronization.

5.If no other communications link is available, the unit functions as a standalone unit when in RUN mode.

After replacement of the faulted Redundancy Communications Module, power must be cycled to restore the RCM to service.

Losing a Link

Losing a Link occurs when a link timeout occurs (that is, no data received in the expected time period). Since the system is not certain that a lost link is due to a hardware failure, the Redundancy Communications Module is not faulted. Some possible causes for a link timeout are:

1.Remote unit has failed and is unable to communicate.

2.Configured fail-wait timeout is too short and a long sweep or communications window has resulted in a link timeout. Normally the other link will continue to function in this case and the PLCs remain synchronized. If the condition continues, the remaining communications link will timeout in a subsequent sweep.

3.A hardware problem is present that prevents data from being transferred but is not detectable by error checking mechanisms such as parity errors (there are no known problems in this category).

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Series 90™-70 Enhanced Hot Standby CPU Redundancy User's Guide – May 2000

GFK-1527A

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Contents GE Fanuc Automation GFL-002 Preface Content of This ManualRelated Publications Preface Contents Contents Chapter Fault Detection Appendix a Cabling Information Introduction Definition of TermsEnhanced Hot Standby CPU Redundancy Using the Redundancy CPU for Non-Redundant Operation Compatibility with CPU780Redundancy CPUs as Compared to Other Series 90-70 CPUs Features not Available with Redundancy CPUsDifferences in Operation for Redundancy CPUs Redundant Racks Enhanced Redundancy CPU ModuleRedundancy Communications Module Systems for Enhanced Hot Standby CPU RedundancyLocal I/O Genius I/OCable Connections Enhanced Hot Standby CPU Redundancy System with Local I/O Local I/0 Can beGHS Control Strategy Control StrategiesGDB Control Strategy Output Control with GHS Basic Enhanced Hot Standby OperationOutput Control with GDB Basic CPU Redundancy Setups Single Bus with Preferred Master GHS Control StrategySingle Bus with Floating Master GDB Control Strategy Critical Data + Redundant Outputs TransferredDual Bus with Floating Master GDB Control Strategy Paired GBC = INT/EXT Internal ExternalOn-Line Repair Online ProgrammingDuplex CPU Redundancy System Components For Installation InstructionsSystem Racks Features Redundancy CPUCPU Architecture Watchdog TimerExpansion Memory Board Battery Connectors CPU FeaturesMemory Protect Keyswitch CPU LEDsCPU Mode Switch PortRedundancy Communications Module Unit Select PushbuttonConnector RCM Status LedsBus Transmitter Module ConnectorsBus Transmitter Module Status LEDs Cables and Termination Bus Receiver ModuleBus Receiver Module Status LEDs Genius Bus Controller Location of GBCs and BlocksSingle Bus Genius Networks Dual Bus Genius NetworksBus Controller LEDs One Application Program in Both PLCs Configuration RequirementsProgrammer Connection for Configuration Program Folders in Control Programming SoftwareCPU Configuration Parameters Program Folders in LogicmasterConfiguring Shared I/O References Parameter Default Range DescriptionFinding the Memory Available for Application Program Storage System Communications Window ConsiderationsRack Module Configuration Parameters Bus Controller Configuration ParametersGenius I/O Block Configuration Parameters Normal Operation Powerup of a Redundant CPU Incompatible Configurations Resynchronization of a Redundant CPUGHS Control Strategy GDB Control StrategyReferences for CPU Redundancy Ovrpre %S Reference Not AvailableScan Synchronization Sweep Time SynchronizationOutput Data Transfer to the Backup Unit AT aData Transfer Time Fail Wait TimeGFK-1527A Normal Operation Programming a Data Transfer from Backup Unit to Active Unit Data Transfer ExampleDisabling Data Transfer Copy in Backup Unit Svcreq #43 Command Block for Svcreq #43 Validating the Backup PLCs Input Scan Backup Qualification with Svcreq #43Validating the Backup PLCs Logic Solution Switching Control to the Backup Unit Switching TimesRUN Disabled Mode for GHS Control Strategy RUN Disabled ModeExample 1 Role switches allowed on both units Example 3 Role switches not allowed on either unit Example 2 Role switches allowed on both unitsExample 4 Role switches allowed on both units Backup Active RUN Disabled Mode for GDB Control Strategy Example 8 InvalidFinding the Words to Checksum Each Sweep CGR772 CGR935Finding the Background Window Time Finding the Total Sweep TimeTimed Contacts Timer and PID Function BlocksMiscellaneous Operation Information Multiple I/O Scan SetsDebugger Stop to RUN Mode TransitionSequential Function Chart Programming SFC Background Window TimeGenius Bus Controller Switching Ethernet Global Data in a Redundancy CPU Ethernet Global Data ConsumptionEthernet Global Data Production Sntp TimestampingFault Detection Configuration of Fault ActionsFault Detection PLC Fault Table Messages for Redundancy Message Fault Description Corrective ActionWith redundancy in other fault groups Fault Response Faulting the Redundancy Communications Module Losing a LinkFault Actions in a CPU Redundancy System Configurable Faults Fault Group Type DescriptionNon-Configurable Fault Group Fatal Faults on Both Units in the Same SweepOn-Line Repair On-Line Repair Recommendations Power SupplyMaintaining Parallel Bus Termination RacksRedundancy Communications Module and Cables Central Processor UnitRedundancy Communications Link Failures Genius Bus Controller Single Bus Networks Bus faultsBus Transmitter Module Genius BusDual Bus Networks Genius BlocksIC690CBL714A Multi-drop Cable SpecificationsCabling Information PurposeConnector a Connector A, 15-pin Female Battery connectors Bus Controller, Genius IndexIndex Online programming Online repair Svcreq