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GFK-0827

Chapter 4Operation

This chapter discusses:

the normal operation of a Hot Standby CPU Redundancy PLC system;

what happens when a fault is detected and the system does not operate normally;

how to restore the system to normal operation;

on-line repair procedures.

Section 1 describes normal system operation of a Series 90-70 Hot Standby CPU

Redundancy system, Section 2 describes what happens when a system failure is

detected, the actions taken by the system in response to detected faults and how to

restore the system to normal operation.

Section 5: System Operation

Power-Up Sequence of a Redundant CPU

When a CPU is powered up, it will perform a complete hardware diagnostic check and a

complete check of the user program and configuration parameters. This will cause the

power up time of a redundant CPU to be significantly longer than the normal power up

time of a simplex (non-redundant) Series 90-70 CPU. If the Primary and Secondary

systems are powering up together each CPU must recognize this fact so that the Primary

system will become the active and the Secondary system the backup.

The following sequence outlines each step in the power-up process. The only difference

in this sequence as compared to the power-up sequence of existing CPUs is that full

power-up tests are always performed instead of conditionally depending on whether STOP

mode is selected, and the detection of the other CPU along with initialization of each

RCM followed by synchronization.

1. Power-up self-test is performed.

2. CPU operating system is initialized and PLC memory is validated.

3. Diagnostics called for ”Full” power-up tests performed.

Contents

Main Warnings, Cautions, and Notes as Used in this Publication Warning Caution Preface Content of this Manual Related Publications Preface We Welcome Your Comments and Suggestions Henry A. Konat Section 2: Fault Detection and Control Actions 72 . . . . . . . . . . . . . . . Page Page 1 Chapter 1Introduction Hot Standby CPU Redundancy Product Page Features of the Hot Standby CPU Redundancy Product Benefits of the Hot Standby CPU Redundancy Product I/O Systems for Hot Standby CPU Redundancy Systems Genius I/O System Local I/O System Cable Connections 5 Y Y * TERMINATED I/O CABLE PRIMARY UNIT SECONDARY UNIT REMOTE DROP Figure 2. Synchronized Hot Standby CPU Redundancy System Configuration other Genius devices Legend Redundancy CPU Module Redundancy Communications Module Bumpless Switching Synchronized CPUs Effect on Scan Time Fail Wait Time Switch to Backup Unit Time Configurable Backup Data Size On-Line Programming On-Line Repair Programming Considerations Configuration Requirements Definition of Terms 12 Series 90-70 Hot Standby CPU Redundancy Users Guide December 1993 Commonly Used Acronyms 2 Chapter 2System Components Redundancy CPU Figure 3. CPU 780 Locations in a Hot Standby CPU Redundancy System Table 1. Capacities for Redundancy CPU, IC697CPU780 CPU Architecture Caution Watchdog Timer 15 CPU Features Figure 4. Redundancy CPU - IC697CPU 780 OK RUN ENABLED MEM PROTECT CENTRAL PROCESSOR UNIT CPU 780 CPU Mode Switch Table 2. Valid Operating Mode Selection Run/Outputs Enabled Run/Outputs Disabled STOP Memory Protect Keyswitch CPU Status LEDs OK RUN ENABLED Serial Port Connector Expansion Memory Board Table 3. Expansion Memory Boards for CPU 780 19 Redundancy Communications Module Figure 5. Redundancy Communications Module - IC697RCM711 RCM Features The following figure shows the features of the RCM module. RCM 711 RCM System Status LEDS BOARD OK LOCAL SYSTEM READY LOCAL SYSTEM ACTIVE REMOTE SYSTEM READY Unit Selection Pushbutton RCM Connectors Bus Transmitter Module Module OK Programmer Port Enabled Expansion Port Enabled BTM Connectors Bus Receiver Module I/O Bus Signal Termination LED Status Indicators Board OK Last Rack Genius Bus Controller Genius Bus Controller User Features Module OK CH 1 OK GBC Connectors Figure 7. Example of Multiple Genius Busses in a Hot Standby CPU Redundancy System Racks 3 Chapter 3Configuration Configuring a Hot Standby CPU Redundancy System Redundancy System Requirements Basic Redundancy System Setup Logicmaster 90 Configuration For both Primary and Secondary CPUs, do the F ollowing: I/O System Configuration Screens for Fault Category Configuration Handling Folders Configuration with Logicmaster 90-70 Configuration of a Redundancy CPU Module Page Redundant CPU Requirements Redund Type Background Window Normal Sweep Mode Constant Window Sweep Mode Constant Sweep Mode Ctrl Strgy Fail Wait Shared I/O 37 Table 4. Shared I/O Data Parameters Transfer Data Size Table 6. Transfer Data Size Interrupts Configuring a CPU Expansion Memory Board Configuration of a Redundancy Communications Module Page Configuration of a Genius Bus Controller Paired GBC Parameter Serial 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 Page Configure Genius I/O Blocks Configure the Bus Transmitter Module Configuring a Secondary Redundant PLC Change Redund Type Page 4 Chapter 4Operation Section 5: System Operation Power-Up Sequence of a Redundant CPU Incompatible Configurations Resynchronization of the Redundant CPU Hot-Standby Redundancy Control Strategy Synchronous Scan Figure 8. Active and Backup Sweeps First Data Transfer %I, %AI and Synchronization Data Transfer from Backup Unit to Active Unit Second Data Transfer %Q, %AQ, %R, and %M Switching Control to Backup Unit Role Switch SVCREQ %S References for CPU Redundancy Table 7. Definition for% S Reference for Redundancy Status Redundancy CPU Considerations Features not Available with CPU 780 I/O Interrupts Timed Interrupts VME Integrator Racks STOP/IOSCAN Mode Differences in Operation for CPU 780 RUN Disabled Mode Page Configuration of Fault Actions STOP to RUN Mode Transition Background Window Time Background User Checksum and Background Window Timing Instructions Miscellaneous Operation Information Timer and PID Function Blocks Timed Contacts OVR_PRE %S Reference Genius Bus Controller Switching Section 6: Fault Detection and Control Actions Fault Detection Fault Categories Changing Fault Category Actions 74 Series 90-70 Hot Standby CPU Redundancy Users Guide December 1993 PLC Fault Table Table 8. Fault Zoom Help Text for Redundancy Error Codes Error Code Message Fault Description Corrective Action Faulting RCMs, Losing Links, and Terminating Communications Page Fault Actions in a CPU Redundancy System Table 9. Maskable Fault Group Descriptions Table 10. Maskable Fault Group Actions 79 Table 11. Non-Maskable Fault Group Descriptions Fault Group Table Type Description Table 12. Non-Maskable Fault Action Descriptions Fault Actions Fault Group Simplex Mode Redundant Mode On-Line Repair Maintaining Parallel Bus Termination On-Line Repair Recommendations Power Supply Racks Central Processor Unit Redundancy Communications Module and Cables Redundancy Communications Link Failures Bus Transmitter Module Genius Bus Controller Genius Bus Genius Blocks A Appendix ARedundancy Alternatives Redundancy Alternatives Note that the redundancy option described in this manual is the Hot Standby Product. 86 Series 90-70 Hot Standby CPU Redundancy Users Guide - December 1993 Figure 9. Guide to Selection of Redundancy Option Key for Table 1 (Redundancy Options) Redundancy Option Key (see Table 1) Fault Tolerant Fail Safe Use This Guide to Select the Redundancy Option Key for the Available Redundancy Options Table 13. Redundancy Options See list of restrictions below. Explanation of terms used in the above Table of Redundancy Options. Series 90-70 Redundancy Through Application Logic A B C D E F G H I K L M P R S T W