ContentsGFK-1527A v
Chapter 1 Introduction.....................................................................................................1-1
Enhanced Hot Standby CPU Redundancy.....................................................................1-2
Features of Enhanced Hot Standby CPU Redundancy...................................................1-3
Using the Redundancy CPU for Non-Redundant Operation....................................1-3
Compatibility with CPU780................................................................................... 1-3
Redundancy CPUs as Compared to Other Series 90-70 CPUs.......................................1-4
Features not Available with Redundancy CPUs...................................................... 1-4
Differences in Operation for Redundancy CPUs..................................................... 1-4
Components of the Enhanced Hot Standby Redundancy System...................................1-5
Enhanced Redundancy CPU Module......................................................................1-5
Redundancy Communications Module....................................................................1-5
Redundant Racks....................................................................................................1-5
I/O Systems for Enhanced Hot Standby CPU Redundancy......................................1-5
Genius I/O............................................................................................................1-6
Local I/O..............................................................................................................1-6
Cable Connections................................................................................................1-6
Enhanced Hot Standby CPU Redundancy System with Local I/O.......................... 1-7
Control Strategies......................................................................................................... 1-8
GHS Control Strategy........................................................................................... 1-8
GDB Control Strategy...........................................................................................1-8
Basic Enhanced Hot Standby Operation........................................................................1-9
Output Control with GHS......................................................................................1-9
Output Control with GDB.....................................................................................1-9
Basic CPU Redundancy Setups...................................................................................1-10
Single Bus with Preferred Master: GHS Control Strategy.....................................1-10
Single Bus with Floating Master: GDB Control Strategy......................................1-11
Dual Bus with Floating Master: GDB Control Strategy........................................1-12
Duplex CPU Redundancy....................................................................................1-13
Online Programming...................................................................................................1-13
On-Line Repair...........................................................................................................1-13
Chapter 2 System Components........................................................................................2-1
System Racks...............................................................................................................2-1
Redundancy CPU.........................................................................................................2-2
Features................................................................................................................2-2
CPU Architecture.........................................................................................................2-3
Expansion Memory Board.....................................................................................2-3
Watchdog Timer...................................................................................................2-3
CPU Features...............................................................................................................2-4
Memory Protect Keyswitch...................................................................................2-4
CPU LEDs............................................................................................................2-4
Battery Connectors................................................................................................2-4
CPU Mode Switch................................................................................................2-5
Run/Outputs Enabled Mode............................................................................2-5
Run/Outputs Disabled Mode...........................................................................2-5
Stop Mode.....................................................................................................2-5
Port 1....................................................................................................................2-5