State Industries GFK-0827 1

1section level 1 1

figure bi level 1

table_big level 1

restart lowapp ARestart oddapp: ARestarts for autonumbers that do not restart in

each chapter. figure bi level 1, reset table_big level 1, reset chap_big level 1, reset1

Lowapp Alwbox restart evenap:A1app_big level 1, resetA figure_ap level 1, reset

table_ap level 1, reset figure level 1, reset Figure 1. table level 1, reset Table 1.

these restarts oddbox reset: 1evenbox reset: 1must be in the header frame of

chapter 1. a:ebx, l 1 resetA a:obx:l 1, resetA a:bigbx level 1 resetA a:ftr level 1 resetA

c:ebx, l 1 reset1 c:obx:l 1, reset1 c:bigbx level 1 reset1 c:ftr level 1 reset1

Reminders for autonumbers that need to be restarted manually (first instance will

always be 4) let_in level 1: A. B. C. letter level 1:A.B.C. num level 1: 1. 2. 3.

num_in level 1: 1. 2. 3. rom_in level 1: I. II. III. roman level 1: I. II. III. steps level 1:

1. 2. 3.

GFK-0827

This chapter is an introduction to a method of CPU Redundancy for the Series 90-70

Programmable Logic Controller which is referred to as the Hot Standby CPU

Redundancy product.

The contents of this chapter provide:

a basic description of what Hot Standby CPU Redundancy is;

tells what it does for you - the user;

provides a basic description of the components of the Hot Standby CPU

Redundancy system;

provides a basic description of how a system is configured using the Logicmaster

90-70 programming software configurator function;

lists certain restrictions that you must be aware of;

and defines terminology unique to this product.

Note

For those who are not familia r with th e various redundancy alterna tives

which may be applied to a Series 90-70 PLC system, please refer to

Appendix A before proceeding with this chapter. For those who are f a m i l ia r

with those redundancy alter natives please proceed with the dicussion of the ’Hot

Standby CPU Redundancy Product” below.

CPU Redundancy for the Series 90-70 Programmable Logic Controller provides a

method of allowing a critical application or process to continue operating if a failure

occurs in any single component. The CPU Redundancy system described in this guide

is the Hot Standby CPU Redundancy product. A Hot Standby CPU Redundancy system

consists of two CPUs connected to one or more Genius I/O buses. Each PLC is

configured as either Primary or Secondary. The Primary PLC is the preferred PLC and