GE 90-70 manual Introduction, Definition of Terms

Page 9

Chapter

1

Introduction

This chapter introduces the method of CPU Redundancy for the Series 90-70 Programmable Logic Controller, which is referred to as Enhanced Hot Standby CPU Redundancy. The contents of this chapter describe:

Enhanced Hot Standby CPU Redundancy

Components of the Enhanced Hot Standby Redundancy System

Control Strategies

YBasic Enhanced Hot Standby Operation Basic CPU Redundancy Systems

Definition of Terms

Active Unit	The unit that is currently controlling the process.

Backup Unit	That unit that is synchronized with the active unit and able to take over the process.

CPU Redundancy	A system with two PLC CPU units cooperating to control the same process.

Critical Component	A component whose failure causes the PLC (either active or backup) where it resides to stop.

Hot Standby	A feature of Genius devices whereby the device prefers output data from the Bus Controller at Serial Bus
	Address 31. When outputs from that Bus Controller are not available, the device takes output data from the
	Bus Controller at Serial Bus Address 30. If outputs from neither Controller are available, the device places its
	outputs in the designated default state.

Primary Unit	The unit in which the externally redundant Bus Controllers' Serial Bus Address is 31.

Redundancy	The use of multiple elements controlling the same process to provide alternate functional channels in case of
	failure.

Secondary Unit	The unit in which the externally redundant Bus Controllers' Serial Bus Address is 30.

Synchronized	A unit is considered to be synchronized when it has received the latest status information from the Active unit
	and is running the PLC program in parallel.

Dual Bus	The use of two Genius busses to control the same I/O devices. The busses are linked to the I/O devices by one
	or more Bus Switching Modules (BSMs). A BSM will automatically switch to the other bus if the active bus
	has a failure.

Local System	(LEDs on RCM) - The system where the RCM resides. LEDs indicate whether the local unit is ready to
	become the active unit or is the active unit in a redundancy system.

Remote System	(LEDs on RCM) - The system to which the RCM is connected via the communications cable. LEDs indicate
	whether the remote unit is ready to become the active unit or is the active unit in a redundancy system.

GFK-1527A

1-1

Image 9

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