State Industries GFK-0827 manual Resynchronization of the Redundant CPU

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Resynchronization of the Redundant CPU

Whenever a CPU is attempting to get back in synchronization with the currently active CPU, a resynchronization process will occur. This resynchronization process will occur any time a CPU performs a STOP to RUN mode transition. This process will start by determining which role each CPU is to play. The Primary Unit (with Serial Bus Address

31)is always preferred and a switch will occur from the Secondary Unit anytime the primary CPU performs a resynchronization. However, until the resynchronization is complete, the primary CPU will play the role of the backup. The Primary unit will switch to active just prior to logic execution. Outputs will be driven that sweep by the primary unit.

If both systems are transitioning at the same time, then the primary CPU will become the active CPU and the secondary will become the backup.

During the resynchronization process, data is exchanged between the CPUs regarding roles and configuration. If the transitioning CPU detects that the role or configuration is not in agreement, then that CPU will not be permitted to go to RUN mode. If both CPUs are transitioning, then neither CPU will be permitted to go to RUN mode. The following items must be in agreement:

1.One CPU must be configured as Primary, the other as Secondary.

2.Both CPUs must be configured for the same redundancy scheme; but not necessarily the same release.

3.Both CPUs must have the same Shared I/O redundancy points configured.

4.Point fault configuration must match. If point faults are configured on one CPU, they must also be configured on the other if %I, %Q, %AI, or %AQ data is transferred.

At this point, the active unit is the one that has been in control and the backup unit is the one that is resynchronizing. The transfer of all configured control data from the active unit to the backup will occur provided both units are not transitioning at the same time (the transfer always goes from the running unit to the resynching unit. In addition to the configured control data, the FST_SCN and FST_EXE %S references as well as internal timer information for each common (that is, present in both CPUs) sub-block are transferred from active to backup. Only the internal timers and FST_EXE references for program blocks with the same name will be transferred from the active to the backup CPU. The result of this is that if one CPU is already on-line and the other is transitioning to RUN mode, its FST_SCN and matching FST_EXE bits will not be set on its first scan. These bits are considered system bits and will only be set if one unit comes up alone, or if both units come up together.

No transfer of data occurs at this point if both units are transitioning. Instead, the normal clearing of non-retentive data will happen and the FST_SCN and FST_EXE references will be set as in the non-redundant simplex CPU models.

The timer information and the FST_EXE %S reference bits will not be continuously transferred. The timer information and FST_EXE references will be transferred only at resynchronization time and the timer information will be calculated each sweep from the universal ºStart of Sweep Timeº that is transferred every sweep.

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Chapter 4 Operation

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Contents GE Fanuc Automation GFL±002 Content of this Manual Related PublicationsPreface We Welcome Your Comments and SuggestionsContents Chapter System Components Chapter Configuration Chapter Operation System Operation Fault Detection and Control Actions Synchronized Hot Standby CPU Redundancy System Configuration Contents Chapter Introduction Hot Standby CPU Redundancy ProductGFK-0827 Features of the Hot Standby CPU Redundancy Product Benefits of the Hot Standby CPU Redundancy ProductSystems for Hot Standby CPU Redundancy Systems Genius I/O SystemLocal I/O System Cable ConnectionsBasic Hot Standby Operation Control StrategySynchronized Hot Standby CPU Redundancy System Configuration Redundancy CPU Module Redundancy Communications ModuleBumpless Switching Switch to Backup Unit TimeSynchronized CPUs Effect on Scan TimeOn-Line Repair Configurable Backup Data SizeOn-Line Programming Configuration Requirements Programming ConsiderationsDefinition of Terms Term DefinitionCommonly Used Acronyms Acronym DefinitionChapter System Components Redundancy CPUCapacities for Redundancy CPU, IC697CPU780 Watchdog TimerCPU Architecture CPU Features Redundancy CPU IC697CPUCPU Mode Switch Valid Operating Mode SelectionCPU Status LEDs Memor y Protect KeyswitchBattery Connectors Expansion Memory Boards for CPU Serial Port ConnectorExpansion Memory Board RCM Features Redundancy Communications ModuleRCM System Status Leds Board OKRCM Connectors Unit Selection PushbuttonLED Status Indicators Bus Transmitter ModuleBTM Connectors Bus Receiver ModuleGenius Bus Controller Bus Signal TerminationBRM Connectors Genius Bus Controller User Features GBC Connectors RacksChapter Configuration Configuring a Hot Standby CPU Redundancy SystemBasic Redundancy System Setup Logicmaster 90 ConfigurationSystem Configuration Redundancy System RequirementsScreens for Fault Category Configuration Monitor or Online modeConfiguration with Logicmaster Handling FoldersConfiguration of a Redundancy CPU Module GFK-0827 Redundant CPU Requirements Background Window Normal Sweep ModeRedund Type Constant Window Sweep Mode Constant Sweep ModeShared I/O Ctrl StrgyFail Wait Shared I/O Data Parameters Shared I/O Reference ValuesTransfer Data Size Reference Type ReferenceSize CalculationforNumberofBytesConfiguring a CPU Expansion Memory Board Configuration of a Redundancy Communications Module Configuration Configuration of a Genius Bus Controller Paired GBC ParameterSerial Bus Address Configuring a Primary Redundant PLC Select the Redundancy CPU Module Select an Expansion Memory Board Configure the Redundant Communications Module Configure a Genius Bus Controller Configuration Configure Genius I/O Blocks Configure the Bus Transmitter Module Configuring a Secondary Redundant PLC Change Redund Type GFK-0827 Power-Up Sequence of a Redundant CPU Chapter OperationIncompatible Configurations Resynchronization of the Redundant CPU Hot-Standby Redundancy Control Strategy Synchronous Scan First Data Transfer %I, %AI and SynchronizationData Transfer from Backup Unit to Active Unit Switching Control to Backup Unit Second Data Transfer %Q, %AQ, %R, and %MRole Switch Svcreq References for CPU Redundancy Definition for% S Reference for Redundancy StatusRedundancy CPU Considerations RUN Disabled Mode Differences in Operation for CPURUN/ENABLED Locrdy Locact Remrdy Remact Configuration of Fault Actions Stop to RUN Mode Transition Background Window TimeWords per Sweep = Timed Contacts Ovrpre %S ReferenceGenius Bus Controller Switching Fault Detection Fault CategoriesChanging Fault Category Actions PLC Fault Table Fault Zoom Help Text for Redundancy Error CodesFaulting RCMs, Losing Links, and Terminating Communications GFK-0827 Fault Actions in a CPU Redundancy System Maskable Fault Group DescriptionsMaskable Fault Group Actions UserConfigurableNon-Maskable Fault Group Descriptions Non-Maskable Fault Action DescriptionsOn-Line Repair Recommendations On-Line RepairMaintaining Parallel Bus Termination Power Supply RacksCentral Processor Unit Redundancy Communications Module and CablesGenius Bus Controller Redundancy Communications Link FailuresBus Transmitter Module Genius Bus GeniusBlocksAppendix Redundancy Alternatives Redundancy AlternativesRedundancy Option Key See Table RedundancyOptions PLCSeries 90-70 Redundancy Through Application Logic Index Index Index Index Index
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