Rockwell Automation 1791-IOBB User Manual

Block I/O
Cat. No. 1791-IOBA and -IOBB

User Manual

Important User Information

Because of the variety of uses for this product and because of the
differences between solid state products and electromechanical products,
those responsible for applying and using this product must satisfy
themselves as to the acceptability of each application and use of this
product. For more information, refer to publication SGI–1.1 (Safety
Guidelines For The Application, Installation and Maintenance of Solid
State Control).

The illustrations, charts, and layout examples shown in this manual are
intended solely to illustrate the text of this manual. Because of the many
variables and requirements associated with any particular installation,
Allen–Bradley Company cannot assume responsibility or liability for
actual use based upon the illustrative uses and applications.

No patent liability is assumed by Allen–Bradley Company with respect to
use of information, circuits, equipment or software described in this text.

Reproduction of the contents of this manual, in whole or in part, without
written permission of the Allen–Bradley Company is prohibited.

Throughout this manual we make notes to alert you to possible injury to
people or damage to equipment under specific circumstances.

WARNING: Tells readers where people may be hurt if
procedures are not followed properly.

CAUTION: Tells readers where machinery may be damaged
or economic loss can occur if procedures are not followed
properly.

Warnings and Cautions:

- Identify a possible trouble spot.

- Tell what causes the trouble.

- Give the result of improper action.

- Tell the reader how to avoid trouble.

Important: We recommend you frequently backup your application
programs on appropriate storage medium to avoid possible data loss.

 1991 Allen-Bradley Company, Inc.

PLC is a registered trademark of Allen-Bradley Company, Inc.
SLC is a registered trademark of Allen-Bradley Company, Inc.

Summary of Changes

Summary of Changes

Summary of Changes

This issue of the manual contains new information and updated
information.

New Information

This version of the manual includes the addition of the 1791–IOBB block
I/O module.

The 1791–IOBB block I/O module has:

10 inputs
6 outputs

Updated Information

This manual also includes the addition of information previously included
in publication 1791–6.5.1–DU1, the documentation update which covered
the 1791–IOBB block I/O module. This manual also includes revised
specifications for both the –IOBA and –IOBB.

To help you find new and updated information in this manual, we have
included change bars as shown to the right of this paragraph.

S-1

Table of Contents

Important User Information

. . . . . . . . . . . . . . . . . . . . . . . .

Summary of Changes S-1. . . . . . . . . . . . . . . . . . . . . . . . . . . .

Using This Manual 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Purpose
Audience 11
Vocabulary 11
Manual Organization 11

of Manual

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Warnings and Cautions 12
Related

Publications

. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Introducing Block I/O 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Chapter
General Description 21
How
Summary 24

Objectives

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Block I/O Fits in a PLC System

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

22. . . . . . . . . . . . . . . . . . . . . . .

Installing Block I/O 31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

I

Chapter
Pre-installation Considerations 31
Installing
Connecting Wiring 33
Remote
Extended
Compatibility of 1771 I/O Products with Extended Node Numbers 39
Summary 39

Objectives

. . . . . . . . . . . . . . . . . . . . . . . . . .

the Block I/O

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

I/O Link or Distributed I/O Link Wiring

Node Capability

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

32. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

36. . . . . . . . . . . . . . .

38. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. .

Configuring Your Block I/O for PLC

Family Programmable Controllers

Chapter
Setting
Summary 46

Objectives

the Configuration Switches

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

41. . . . . . . . . . . . . . .

41. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

41. . . . . . . . . . . . . . . . . . . . . . . .

Table of Contentsii

Configuring Your Block I/O for SLC Controllers 51. . . . . . . . .

Chapter
Setting
Addressing the Blocks Using SLC Controllers 53
Summary 53

Objectives

the Configuration Switches

. . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

51. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

51. . . . . . . . . . . . . . . . . . . . . . . .

Troubleshooting 61. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Chapter
LED Indicators 61
Summary 62

Objectives

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

61. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Specifications A1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Using This Manual

Chapter

1

Purpose of Manual

Audience

Vocabulary

Manual Organization

This manual shows you how to use your Block I/O with an Allen–Bradley
programmable controller. It helps you install, program and troubleshoot
your module.

You must be able to program and operate an Allen–Bradley programmable
controller (PLC) to make efficient use of Block I/O modules.

We assume that you know how to do this in this manual. If you do not,
refer to the appropriate PLC programming and operations manual before
you attempt to program this module.

In this manual, we refer to:

the block I/O module as the “block” or the “module”

the programmable controller as the “controller”

This manual is divided into 6 chapters. The following chart shows each
chapter with its corresponding title and brief overview of the topics
covered in that chapter.

Chapter Title Topics Covered

2 Introducing Block I/O Description of the modules, including general and

hardware features

3 Installing Block I/O Module power requirements, location, and wiring

information

4 Configuring your block I/O for PLC family

programmable controllers

5 Configuring Your Block I/O for SLC

Controllers

6 Troubleshooting How to use the indicators to troubleshoot your block

Appendix A Specifications Specifications for the block I/O.

How to set the configuration switches and address
the block I/O.

How to set the switches, and where to go for full
information

I/O module.

11

Chapter 1

Using This Manual

Warnings and Cautions

Related Publications

This manual may contain warnings and cautions. A warning tells where
you may be injured if you use your equipment improperly. Cautions tell
where equipment may be damaged from misuse.

You should read and understand cautions and warnings before performing
the procedures they precede.

For a list of publications with information on Allen–Bradley
programmable controller products, consult our publication index (SD499).

12

Introducing Block I/O

Chapter

2

Chapter

Objectives

General Description

In this chapter you will learn what block I/O is, and its features, and how
it functions.

Block I/O consists of small, self–contained remote I/O devices complete
with power supply, programmable controller interface, input/output
connections and signal conditioning circuitry.

Two types of block I/O are available. The 1791–IOBA has 8 inputs and 8
outputs; the 1791–IOBB has 10 inputs and 6 outputs. In all other aspects,
they are identical.

The blocks are compatible with PLC–2, PLC–3, and PLC–5 family
programmable controllers, and the SLC 500 modular controllers. When
used with PLC–2 family programmable controllers, a sub I/O scanner
module (cat. no. 1771–SN) or remote I/O scanner module (cat. no.
1772–SD2) is used to communicate with the blocks. When used with
PLC–3 and PLC–5 family programmable controllers, they can be
connected directly to the controller, a scanner module, or through a remote
I/O adapter module. When used with SLC 500 controllers, a 1747–DSN
scanner (or the 1747–SN Remote I/O scanner) is used to communicate
with the blocks.

Physical features of the block I/O are shown in Figure 2.1.

Figure 2.1

Features of the Block I/O Module (1791-IOBA shown)

Major

DH-485 Port

Removable Remote I/O Link Connector

Switch Assemblies

OUTPUT

INPUT

Communication LED Power LEDStatus Indicators

COMM POWER

Removable Input/Output Connector

10825-I

21

Chapter 2

Introducing Block I/O

Wiring Connectors – The remote I/O link connector and input/output
connector are removable for easy connection of wiring.

Switch Assemblies – Two DIP switches are provided for setting the I/O
rack number, starting I/O group, transmission rate, last chassis, last state
and DH–485 terminator.

Status Indicators – LED indicators are provided for communication,
power and input/output status. These provide a visual indication for aid in
troubleshooting.

DH–485 Port – A plug–in port is provided for use with DH–485 data link
when used with the SLC controller.

How Block I/O Fits in a PLC System

Block I/O is a complete I/O interface that includes the functionality of the
I/O rack, adapter, power supply, and I/O modules in a single unit. Simply
connect sensors and actuators to the module and use the remote I/O cable
to connect the block I/O to your programmable controller (Figure 2.4).

The block uses sinking inputs and sourcing outputs.

In sinking inputs(Figure 2.2), the dc common is bussed on the block. and
the current is sourced from the field device. The sourcing field device
switches the hot side of the power supply bus causing current to flow
through the sourcing device to the sinking input on the block.

Figure 2.2

Input Example

Sinking

+V

Field

Device

Field

Device

Block I/O

Sinking

Input

22

DC Power

Supply

-V

COM

Input Common (COM)

10826-I

Sourcing outputs(Figure 2.3) have the power bussed in the block. When
the output is on, current is supplied to the field control device, which sinks
the current. The field circuit and the equipment remain at ground potential
until the output is turned on.

Chapter 2

Introducing Block I/O

Figure 2.3
Sourcing

Output Example

Block I/O

GND

+V

Fuse

Fuse

Field

Device

Field

Device

Common

DC Power

Supply

-V

Bus

10827-I

You connect the block I/O to your remote I/O link as you would any other
device (Figure 2.4). The block looks like a 1/4 I/O rack to the processor,
and uses 2 words of input image table memory and 2 words of output
image table memory. The block is addressed directly on the remote I/O
link.

Programmable Controller
or Scanner

.

Block I/O functions exactly like any Allen–Bradley remote I/O product.
Input and output data is scanned asynchronously and transferred back and
forth between the block and the controller input and output image table.

Figure 2.4

I/O Connection in a PLC System

Block

Blocks are daisy-chained to
a programmable controller
or a scanner

Block I/O - each block
is 1/4 I/O rack.

.

10828-I

23

Chapter 2

Introducing Block I/O

Summary

In this chapter you learned what block I/O is, its features and how it
functions.

24