GE 90-70 manual Fault Response

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5

Fault Response

The Enhanced Hot Standby CPU Redundancy system detects and reports failures of all critical components so that appropriate control actions may be taken. All components that acquire or distribute I/O data or that are involved in execution of the control logic solution are considered critical components.

In a Redundancy system, fault actions are not configurable as they are in a non-redundancy system. A FATAL fault in the active unit causes a switch of control to the backup unit. A DIAGNOSTIC fault allows the currently-active system to continue operating as the active system.

Faults within the PLC may be such that:

1.the PLC has a controlled shutdown,

2.the PLC has an uncontrolled shutdown, or

3.the PLC continues to operate.

If the PLC detects an internal fault and has a controlled shutdown, a fault is logged in the fault table, the other PLC is notified of the fault, and the faulted PLC goes to stop mode and stops driving outputs. This does not normally occur until the top of the sweep following the failure. The exception is when the failure occurs during the input scan. In that case, upon notification, the backup system immediately takes over and starts driving outputs.

If the PLC has an uncontrolled shutdown, the PLC logs a fault if it can and proceeds as described above. If the backup PLC detects that the active PLC has failed to synchronize, it assumes the active unit has failed after timing out all (both) available links. The backup then starts driving outputs and controlling the process. If a fault exists within the PLC that has not been detected, the system eventually detects the fault through the background diagnostic procedure. When the fault is detected, the PLC proceeds with the orderly shutdown process if it can.

If the two PLCs fail to synchronize, because the timeout is set too short, the two systems start to act independently. A fault is logged at the time synchronization failure occurs.

GFK-1527A

Chapter 5 Fault Detection

5-5

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Contents GE Fanuc Automation GFL-002 Content of This Manual PrefaceRelated Publications Preface Contents Contents Chapter Fault Detection Appendix a Cabling Information Definition of Terms IntroductionEnhanced Hot Standby CPU Redundancy Compatibility with CPU780 Using the Redundancy CPU for Non-Redundant OperationFeatures not Available with Redundancy CPUs Redundancy CPUs as Compared to Other Series 90-70 CPUsDifferences in Operation for Redundancy CPUs Redundancy Communications Module Enhanced Redundancy CPU ModuleRedundant Racks Systems for Enhanced Hot Standby CPU RedundancyGenius I/O Local I/OCable Connections Local I/0 Can be Enhanced Hot Standby CPU Redundancy System with Local I/OControl Strategies GHS Control StrategyGDB Control Strategy Basic Enhanced Hot Standby Operation Output Control with GHSOutput Control with GDB Single Bus with Preferred Master GHS Control Strategy Basic CPU Redundancy SetupsCritical Data + Redundant Outputs Transferred Single Bus with Floating Master GDB Control StrategyPaired GBC = INT/EXT Internal External Dual Bus with Floating Master GDB Control StrategyOnline Programming On-Line RepairDuplex CPU Redundancy For Installation Instructions System ComponentsSystem Racks Redundancy CPU FeaturesWatchdog Timer CPU ArchitectureExpansion Memory Board Memory Protect Keyswitch CPU FeaturesBattery Connectors CPU LEDsPort CPU Mode SwitchUnit Select Pushbutton Redundancy Communications ModuleRCM Status Leds ConnectorConnectors Bus Transmitter ModuleBus Transmitter Module Status LEDs Bus Receiver Module Cables and TerminationBus Receiver Module Status LEDs Location of GBCs and Blocks Genius Bus ControllerDual Bus Genius Networks Single Bus Genius NetworksBus Controller LEDs Programmer Connection for Configuration Configuration RequirementsOne Application Program in Both PLCs Program Folders in Control Programming SoftwareProgram Folders in Logicmaster CPU Configuration ParametersParameter Default Range Description Configuring Shared I/O ReferencesSystem Communications Window Considerations Finding the Memory Available for Application Program StorageBus Controller Configuration Parameters Rack Module Configuration ParametersGenius I/O Block Configuration Parameters Normal Operation Powerup of a Redundant CPU Resynchronization of a Redundant CPU Incompatible ConfigurationsGDB Control Strategy GHS Control StrategyOvrpre %S Reference Not Available References for CPU RedundancySweep Time Synchronization Scan SynchronizationAT a Output Data Transfer to the Backup UnitFail Wait Time Data Transfer TimeGFK-1527A Normal Operation Data Transfer Example Programming a Data Transfer from Backup Unit to Active UnitDisabling Data Transfer Copy in Backup Unit Svcreq #43 Command Block for Svcreq #43 Backup Qualification with Svcreq #43 Validating the Backup PLCs Input ScanValidating the Backup PLCs Logic Solution Switching Times Switching Control to the Backup UnitRUN Disabled Mode RUN Disabled Mode for GHS Control StrategyExample 1 Role switches allowed on both units Example 2 Role switches allowed on both units Example 3 Role switches not allowed on either unitExample 4 Role switches allowed on both units Backup Active Example 8 Invalid RUN Disabled Mode for GDB Control StrategyCGR772 CGR935 Finding the Words to Checksum Each SweepFinding the Total Sweep Time Finding the Background Window TimeMiscellaneous Operation Information Timer and PID Function BlocksTimed Contacts Multiple I/O Scan SetsSequential Function Chart Programming SFC Stop to RUN Mode TransitionDebugger Background Window TimeGenius Bus Controller Switching Ethernet Global Data Consumption Ethernet Global Data in a Redundancy CPUSntp Timestamping Ethernet Global Data ProductionConfiguration of Fault Actions Fault DetectionFault Detection Message Fault Description Corrective Action PLC Fault Table Messages for RedundancyWith redundancy in other fault groups Fault Response Losing a Link Faulting the Redundancy Communications ModuleFault Actions in a CPU Redundancy System Fault Group Type Description Configurable FaultsFatal Faults on Both Units in the Same Sweep Non-Configurable Fault GroupOn-Line Repair Maintaining Parallel Bus Termination Power SupplyOn-Line Repair Recommendations RacksCentral Processor Unit Redundancy Communications Module and CablesRedundancy Communications Link Failures Bus Transmitter Module Single Bus Networks Bus faultsGenius Bus Controller Genius BusGenius Blocks Dual Bus NetworksCabling Information SpecificationsIC690CBL714A Multi-drop Cable PurposeConnector a Connector A, 15-pin Female Index Battery connectors Bus Controller, GeniusIndex Online programming Online repair Svcreq