Allen-Bradley PLC-5 User Manual

Publication 1785-UM012D-EN-P - July 2005
4-24 Addressing I/O and Controller Memory
Effectively Using
I/O Memory
The PLC-5 controller automatically allocates both an input and output
memory location to each I/O location. I/O modules generally only use either
the inputs or the outputs. To more effectively use I/O memory, you can use
these methods of placing I/O modules.
Use Application
2-slot Install 16-point I/O modules as an input module and output module pair in
an I/O group. For example, if you place an input module in slot 0, place an
output module in slot 1.
1-slot Install 32-point I/O modules as an input module and an output module
pair in an I/O group. For example, if you place an input module in slot 0,
place an output module in slot 1.
complementary I/O chassis You configure complementary chassis with a primary and complement
chassis pair. You complement the I/O modules I/O group for I/O group
between the two chassis. The I/O modules in the complementary chassis
perform the opposite function of the corresponding modules in the
primary chassis.
By designating a PLC-5 scanner channel as complementary, you can
complement racks 1-7. A channel configured for complementary I/O can’t
scan racks greater than 7. Those PLC-5 controllers that can address rack
numbers greater than 7 can address these racks on another scanner
channel which has not been configured as complementary. The remote
I/O link device (such as a1771-ASB adapter) must also be configured for
complimentary.
For more information see the PLC-5 Reference Guide: Configuring
Complementary I/O for PLC-5 Controllers, publication 1785-6.8.3.

Allen-Bradley PLC-5 Specifications

General

Programming Software	RSLogix 5
Programming Languages	Ladder Logic
Power Supply	120/240V AC or 24V DC
Communication Ports	DH+, Remote I/O, Ethernet/IP, ControlNet
Operating Temperature	0 to 60°C (32 to 140°F)
Relative Humidity	5 to 95% non-condensing
Memory	Up to 64K words (user program and data)

Summary

Preface

Manual Overview

Outlines the manual's three main sections: Design, Operate, and Maintain.

Chapter 1 Understanding Your Programmable Controller

Lay Out the System

Guides on determining network configuration and component placement for PLC-5 systems.

Programming Features

Highlights the programming features of a PLC-5 controller, including ladder logic and SFCs.

Chapter 2 Selecting and Placing I/O

Selecting I/O Modules

Guides on selecting I/O modules to interface with machines and processes.

Chapter 3 Placing System Hardware

Determining the Proper Environment

Details acceptable environmental conditions for controller placement.

Grounding Your System

Provides information on proper grounding guidelines for system hardware.

Chapter 4 Addressing I/O and Controller Memory

I/O Addressing Concept

Explains how controller memory segments are used to address I/O terminals.

Assigning Racks

Details how chassis size and addressing mode determine the number of I/O racks.

Chapter 6 Communicating with Remote I/O

Designing a Remote I/O Link

Outlines steps and guidelines for designing a remote I/O link.

Chapter 8 Communicating with Extended-Local I/O

Configuring the Controller as an Extended-Local I/O Scanner

Guides on configuring channel 2 for extended-local I/O as a scanner.

Chapter 10 Communicating with Devices on a Serial Link

Configuring Channel 0

Explains how to configure channel 0 for DF1 point-to-point, master, slave, or user mode.

Chapter 11 Communicating with Devices on an Ethernet Network

Configuring Channel 2 for Ethernet Communication

Guides on configuring channel 2 for Ethernet communication using manual or BOOTP methods.

Using Advanced Ethernet Functions

Explains advanced functions like broadcast address, subnet masks, and gateways.

Chapter 12 Protecting Your Programs

Passwords and Privileges

Explains how passwords and privileges restrict access to controller files and functions.

Chapter 13 Programming Considerations

Forcing

Explains how to turn input/output bits on/off for testing purposes.

Extended Forcing

Describes how to force discrete I/O, analog I/O, and block-transfer data words.

Chapter 15 Preparing Fault Routines

Understanding the Fault Routine Concept

Explains how fault routines execute when a major fault is encountered.

Monitoring Faults

Describes how to monitor controller faults using the status screen.

Appendix F Troubleshooting

PLC-5 controller

Lists general problems for PLC-5 controllers, probable causes, and recommended actions.

Extended-Local I/O system

Offers troubleshooting guidance for the 1771-ALX adapter module.

Appendix G Cable Reference

Channel 0 Pin Assignments

Shows pin assignments for channel 0 (RS-port) for different serial communication modes.

Ethernet Cable Connections

Describes Ethernet cable connections and transceiver specifications.