GE 90-70 manual Ethernet Global Data Production, Sntp Timestamping

Page 64

4

Ethernet Global Data Production

When the two units of a CPU Redundancy system are synchronized, Ethernet Global Data exchanges are produced only by the active unit. This reduces the amount of traffic on the Ethernet network and simplifies the handling of the exchange by the consumer. In particular, the consumer is able to consume the exchanges in the same way as for exchanges from non-redundant systems.

If the exchanges are to be produced by both units, the units must be configured to have the same producer ID. This way, the consumer does not need to know which unit is producing the exchanges. The configuration of unique production exchanges for the two units is not recommended since the exchanges would only be produced when the unit was active and not when it was backup.

If a unit stops being the active unit, it stops producing Ethernet Global Data exchanges so that the other unit can start producing the EGD exchanges. The new active unit, if any, delays starting production of Ethernet Global Data exchanges long enough to let the other unit stop producing. This is necessary so that both units are not producing Ethernet Global Data exchanges at the same time. That could become confusing to the consumer.

The following formula gives the maximum time after a unit becomes the active unit before it starts producing a given Ethernet Global Data exchange. Note that in certain failure conditions, it may take up to 1 sweep + 2 failwait timeouts for the backup unit to detect the failure of the active unit so that it can become the active unit.

Software Watchdog Timeout +

1 Network Production Period for the Exchange +

2 CPU Sweeps +

220 ms

If both communications links between the Redundancy Communications Modules and Bus Transmitter Modules fail, both units are marked as Active Units and attempt to produce Ethernet Global Data exchanges. If the application cannot tolerate this situation, then it must detect that both units are active and shut down one of the units with a service request function block or other means. The program logic can detect this by sending a running counter from one unit to the other via discrete I/O modules or other means and then checking if the counter still increments after both links have been lost.

If outputs are disabled on the active unit, neither unit produces Ethernet Global Data.

SNTP Timestamping

Ethernet Global Data exchanges can be timestamped using either the PLC CPU's local clock or using a Simple Network Time Protocol (SNTP) clock from a user-provided server on the Ethernet network. SNTP clock timestamping for a given Ethernet Global Data exchange is selected by enabling timestamp synchronization in the configuration of the corresponding Ethernet module. If timestamp synchronization is disabled for a given Ethernet module, then Ethernet Global Data exchanges produced by that module are timestamped with the PLC CPU's local clock.

GFK-1527A

Chapter 4 Normal Operation

4-25

Page 63 Page 65
Image 64
Page 63 Page 65
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 Enhanced Redundancy CPU Module Redundancy Communications ModuleRedundant Racks 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 CPU Features Memory Protect KeyswitchBattery Connectors 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 Configuration Requirements Programmer Connection for ConfigurationOne Application Program in Both PLCs 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 TimeTimer and PID Function Blocks Miscellaneous Operation InformationTimed Contacts Multiple I/O Scan SetsStop to RUN Mode Transition Sequential Function Chart Programming SFCDebugger 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 Power Supply Maintaining Parallel Bus TerminationOn-Line Repair Recommendations RacksRedundancy Communications Module and Cables Central Processor UnitRedundancy Communications Link Failures Single Bus Networks Bus faults Bus Transmitter ModuleGenius Bus Controller Genius BusDual Bus Networks Genius BlocksSpecifications Cabling InformationIC690CBL714A Multi-drop Cable PurposeConnector a Connector A, 15-pin Female Battery connectors Bus Controller, Genius IndexIndex Online programming Online repair Svcreq
Top Page Image Contents