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

Installing Block I/O

1775 S4A, S4B, S5, SR

Note: PLC 5250 requires a

Chapter

3

Chapter

Objectives

Pre-installation Considerations

When using and Maximum Capacity

PLC-2 family 16 blocks with 150 ohm terminator 57.6K 10,000 cable-feet

Any scanner module

In this chapter you will learn how to mount the block, connect the remote
I/O link, connect the input and output wiring to the block, and terminate
the remote I/O link.

Before installation, you must determine:

the number of blocks desired
the total distance of the installation
transmission rate desired
if external fuses are required

Refer to Table 3.A for acceptable combinations.

Table 3.A
Acceptable

Combinations of Processor and Block I/O

Baud Rate

Used

28 blocks with 82 ohm terminator 57.6K 10,000 cable-feet

Network Distance

Maximum

PLC-3 family 16 blocks with 150 ohm terminator 57.6K 10,000 cable-feet

PLC-5 family 16 blocks with 150 ohm terminator 57.6K 10,000 cable-feet

1775S4A, S4B, S5, SR
or SR5 module

Note: PLC5250 requires a
5150RS remote scanner

TABLE CONTINUED ON NEXT PAGE

28 blocks with 82 ohm terminator 115.2K 5,000 cable-feet

32 blocks with 82 ohm terminator 57.6K 10,000 cable-feet

32 blocks with 82 ohm terminator 115.2K 5,000 cable-feet

32 blocks with 82 ohm terminator 230.4K 2,500 cable-feet

32 blocks with 82 ohm terminator 57.6K 10,000 cable-feet

32 blocks with 82 ohm terminator 115.2K 5,000 cable-feet

32 blocks with 82 ohm terminator 230.4K 2,500 cable-feet

31

Chapter 3

Installing Block I/O

When using

SLC-5/01 Controller 1747-DSN Scanner module* 7 blocks 230.4K 2,500 cable-feet

SLC-5/02 Controller 1747-DSN Scanner module* 30 blocks 230.4K 2,500 cable-feet

SLC-5/02 Controller 1747-SN Remote I/O

Scanner Module*

* The DH-485 network, which operates independent of the RIO/DIO network, supports up to 30 DH-485 nodes (blocks or 1747-AIC
isolated couplers). The maximum DH-485 network distance is 4,000 cable-feet.

Installing the Block I/O

Mounting dimensions for the block I/O module are shown in Figure 3.1.

Maximum Capacityand

16 blocks 57.6K

Baud Rate

Used

115.2K

230.4K

Mount the blocks horizontally with a minimum of 2” between blocks. This
air gap is necessary to maintain proper cooling air flow through the block.

8mm

0.31"

Figure 3.1
Mounting

-IOBB)

Depth = 84.33mm (3.32")

Dimensions for the Block I/O Module (Cat. No. 1791-IOBA and

198mm

7.8"

Maximum

Network Distance

10,000 cable-feet
5,000 cable-feet
2,500 cable-feet

10mm

0.39"

10mm

0.39"
16mm

0.63"

OUTPUT

INPUT

180mm

7.1"

212mm

8.35"

COMMPOWER

35mm

1.37"

16mm

0.63"

10829-I

The operating temperature in the air gap between block I/O modules must
not exceed 55

o

C (151oF). The dimensions of the air gap required are

shown in Figure 3.2.

32

Chapter 3

Installing Block I/O

Connecting Wiring

51mm
2"

Figure 3.2
Clearance

Required for Block I/O Modules

OUTPUT

INPUT

51mm
2"

51mm
2"

COMMPOWER

51mm
2"

10830-I

Connections to the block I/O module are made to the removable
connectors which plug into the front of the block. The connector blocks are
keyed to prevent incorrect insertion.

Wiring for the block is shown in Figure 3.3 and Figure 3.4. Remote I/O
link wiring connections are shown in Figure 3.5.

2SHD BACOM1

Remote
I/O Link

(see Figure 3.5)

DH-485
(for SLC

only)

Figure 3.3

and Output Connections for the 1791-IOBA

Input

1791-IOBA

8 OUTPUTS

+24DCNCGVDCO0O1O2O3O4O5 I0 I1I2 I3I4 I5I6 I7COMNC

+24V dc

dc Neutral

Chassis Ground

Output +Vdc

OUTPUT 0
OUTPUT 1
OUTPUT 2
OUTPUT 3
OUTPUT 4
OUTPUT 5
OUTPUT 6
OUTPUT 7

- 8 inputs and 8 outputs

8 INPUTS

O6O7

Input Common

INPUT 7
INPUT 6
INPUT 5
INPUT 4
INPUT 3
INPUT 2
INPUT 1
INPUT 0

10831-I

33

Chapter 3

Installing Block I/O

2 SHD B A COM1

Remote
I/O Link

DH-485
(for SLC

only)

Figure 3.4

W

Input/Output

6 OUTPUTS

+24 DCN CGVDC O0 O1 O2 O3 O4 O5 I0 I1 I2 I3 I4 I5 I6 I7 I8 I9 COMNC

+24V dc

dc Neutral

Chassis Ground

Output +Vdc

OUTPUT 0
OUTPUT 1
OUTPUT 2
OUTPUT 3
OUTPUT 4
OUTPUT 5

iring Connections for the 1791-IOBB

Table 3.B

Block Designations

Wiring

10 INPUTS

Input Common

INPUT 9
INPUT 8
INPUT 7
INPUT 6
INPUT 5
INPUT 4
INPUT 3
INPUT 2

INPUT 1
INPUT 0

1791-IOBA 1791-IOBB

Connector Designation Description Designation Description

Remote I/O Connector 1 Blue wire - RIO 1 Blue wire - RIO

2 Clear wire - RIO 2 Clear wire - RIO

SHD Shield - RIO SHD Shield - RIO

A DH-485 A A DH-485 A

B DH-485 B B DH-485 B

COM DH-485 Common COM DH-485 Common

I/O Connector +24 +24V dc +24 +24V dc

DCN dc neutral DCN dc neutral

CG Chassis ground CG Chassis ground

VDC Output supply VDC Output supply

O0 thru O7 Output 0 thru 7 O0 thru O5 Output 0 thru 5

NC No connection NC No connection

I0 thru I7 Input 0 thru 7 I0 thru I7 Input 0 thru 9

COM Input common COM Input common

34

Chapter 3

Installing Block I/O

Power Supply Requirements

An external 24V dc power supply is required to power the block. Total
current required to power the block is equal to 200mA plus an inrush of

5.5A for 10

µsec for each block. The supply must be able to source an

additional 100mA plus an inrush current of 400mA when a peripheral is
connected.

In addition, the external power supply should have current limiting
capabilities. The voltage range must not exceed 20.5–27.6V dc.

Wiring Requirements

Wiring cable requirements are shown in the following table.

Use Cable Type With

Remote I/O Link or DIO Link Belden 9463 PLC-2, PLC-3, PLC-5 family programmable

DH-485 Data Link Belden 9842 SLC controllers only

Input and Output wiring Up to 14AWG

Connection 1 2 SHD

Clear wire X

Blue wire X

Shield wire X

Table 3.C
Acceptable

Figure 3.5
Remote

T

W

iring Cables for Block I/O Connection

I/O Link W

ighten screw to clamp wire.

iring

Stranded with 3/64
inch insulation

Shield

Clear

controllers and SLC controllers

All

Blue

10832-I

35

Chapter 3

Installing Block I/O

Remote I/O Link or Distributed I/O Link Wiring

To Programmable Controller
or I/O Scanner Module

Blocks must be wired in series as shown in Figure 3.6 or Figure 3.7. Do
not attempt to wire any block in parallel.

The number of blocks used depends not only on the user requirements but
also on the system used. Refer to Table 3.A for maximum block usage for
individual systems.

Figure 3.6
Series

Connection for Block I/O Using PLC-2, PLC-3 or PLC-5 Family

Programmable Controllers

1 I/O Rack

Install terminating resistor on last block.

1 I/O Rack

1 I/O Rack

1 I/O Rack

10833-I

36

To 1747-DSN
Scanner Module

Chapter 3

Installing Block I/O

Figure 3.7

Configurations for Block I/O Using the SLC Programmable

Series
Controller

To 1747-DSN
Scanner Module

Up to 7 blocks
using SLC-5/01
Processor

1

2

29

Install terminating resis
tor
on last block.

Install terminating resis
tor
on last block.

30

Up to 30 blocks with
SLC-5/02

10834-I

37

Chapter 3

Installing Block I/O

Termination Resistor

A termination resistor must be installed on the last block in the series.
Connect the resistor as shown in Figure 3.8. Use the resistor as identified
in Table 3.D.

Figure 3.8
Installing

Tighten screw to clamp

wires and termination resistor.

Table 3.D
Terminator

PLC-2, PLC-3, PLC-5 family,
SLC 500 family

the T

ermination Resistor

Connect termination

resistor across terminals 1

and 2

Requirements

System Terminator Resistor

Termination Resistor

150 ohm - 57.6K and 115.2K baud
82 ohm - 230.4K baud

10835-I

Extended Node Capability

38

If this is the last remote I/O adapter on the remote I/O link in a PLC
system, you must use a terminating resistor to terminate both ends of the
remote I/O link (scanner end and last block end). The size of the terminator
is determined by the system configuration.

Older configurations can use a 150 ohm resistor at both ends. With newer
devices that can support it, you can use an 82 ohm termination resistor at
both ends. The 82 ohm terminators provide ”extended node” capability
which allows you to have up to 32 physical devices on the remote I/O link.
(The number of logical racks capable of being addressed by the scanner is
not affected.)

CAUTION: Devices that are operating at 230.4K baud must
have 82 ohm terminators in place for proper operation.

Chapter 3

Installing Block I/O

Compatibility

of 1771 I/O
Products with Extended
Node Numbers

Summary

Certain products are not compatible with extended node capabilities
obtained with the use of 82 ohm terminators. The following table lists
those products that are not compatible.

Device Series

Scanners - 1771-SN All

1772-SD All

1772-SD2 Series A

1775-SR All

1775-S4A All

1775-S4B All

Adapters - 1771-AS All

1771-ASB Series A

1771-DCM All

Miscellaneous - 1771-AF All

1771-AF1 All

In this chapter you learned how to physically mount your block I/O, make
power wiring connections, make the input/output wiring connections to
the block, and terminate the remote I/O link.

39

Chapter

4

Configuring Your Block I/O for PLC
Family Programmable Controllers

Chapter

Setting the Configuration Switches

Objectives

In this chapter you will learn how to configure your block I/O when used
with PLC family programmable controllers. This includes the following:

setting the configuration switches
addressing the block I/O

Each block I/O module has two 6–position DIP switches for setting:

starting I/O group
I/O rack number
transmission (baud) rate
last chassis
last state
DH–485 terminator

These switches are accessible by opening the door on the left side of the
module (Figure 4.1).

41

Chapter 4

Configuring Your Block I/O for PLC
Family Programmable Controllers

S1 S2

Figure 4.1

Settings

Switch

Starting
I/O Group

0

2

4
6

I/O Rack Number
Switches 3-6
(see Table 4.A, B and C)

Switch

12

On (Closed)

Off (Open) On (Closed)

On (Closed)Off (Open)

Off (Open) Off (Open)

On (Closed)

OUTPUT

INPUT

S1 S2

OPEN

12 3456

Switch as viewed from this end.

Off = Open

On = Closed

12 3456

OPEN

Not
Use
d

COMMPOWER

230.4K

115.2K

57.6K

Reset to 0

Hold last state

Yes

No On (Closed)

Terminate

None

On (Closed)

Off (Open) On (Closed)

On (Closed)

Off (Open)

On (Closed)

Off (Open)

Off (Open)

On (Closed)

56Baud Rate

Off (Open)

On (Closed)

4Last State

3Last Chassis

1DH-485

10836-I

42

Table 4.A

Rack Number and First I/O Group Switch Selections for PLC-2 Family

I/O
Processors

I/O Rack Switch Number
Number 3 4 5 6

1 On (Closed) On (Closed) On (Closed) On (Closed)

2 Off (Open) On (Closed) On (Closed) On (Closed)

3 On (Closed) Off (Open) On (Closed) On (Closed)

4 Off (Open) Off (Open) On (Closed) On (Closed)

5 On (Closed) On (Closed) Off (Open) On (Closed)

6 Off (Open) On (Closed) Off (Open) On (Closed)

7 On (Closed) Off (Open) Off (Open) On (Closed)

Chapter 4

Configuring Your Block I/O for PLC
Family Programmable Controllers

Table 4.B

and PLC-5/250 I/O Rack Addressing

PLC-3

I/O Rack Switch Number I/O Rack Switch Number

Number 3 4 5 6 Number 3 4 5 6

0 On (Closed) On (Closed) On (Closed) On (Closed) 10 On (Closed) On (Closed) On (Closed) Off (Open)

1 Off (Open) On (Closed) On (Closed) On (Closed) 11 Off (Open) On (Closed) On (Closed) Off (Open)

2 On (Closed) Off (Open) On (Closed) On (Closed) 12 On (Closed) Off (Open) On (Closed) Off (Open)

3 Off (Open) Off (Open) On (Closed) On (Closed) 13 Off (Open) Off (Open) On (Closed) Off (Open)

4 On (Closed) On (Closed) Off (Open) On (Closed) 14 On (Closed) On (Closed) Off (Open) Off (Open)

5 Off (Open) On (Closed) Off (Open) On (Closed) 15 Off (Open) On (Closed) Off (Open) Off (Open)

6 On (Closed) Off (Open) Off (Open) On (Closed) 16 On (Closed) Off (Open) Off (Open) Off (Open)

7 Off (Open) Off (Open) Off (Open) On (Closed) 17 Off (Open) Off (Open) Off (Open) Off (Open)

Table 4.C

I/O Rack Addressing

PLC-5

I/O Rack Switch Number I/O Rack Switch Number

Number 3 4 5 6 Number 3 4 5 6

01 Off (Open) On (Closed) On (Closed) On (Closed) 10 On (Closed) On (Closed) On (Closed) Off (Open)

02 On (Closed) Off (Open) On (Closed) On (Closed) 11 Off (Open) On (Closed) On (Closed) Off (Open)

03 Off (Open) Off (Open) On (Closed) On (Closed) 12 On (Closed) Off (Open) On (Closed) Off (Open)

PLC-5/15 processors can scan racks 01-03 13 Off (Open) Off (Open) On (Closed) Off (Open)

04 On (Closed) On (Closed) Off (Open) On (Closed) 14 On (Closed) On (Closed) Off (Open) Off (Open)

05 Off (Open) On (Closed) Off (Open) On (Closed) 15 Off (Open) On (Closed) Off (Open) Off (Open)

06 On (Closed) Off (Open) Off (Open) On (Closed) 16 On (Closed) Off (Open) Off (Open) Off (Open)

07 Off (Open) Off (Open) Off (Open) On (Closed) 17 Off (Open) Off (Open) Off (Open) Off (Open)

PLC-5/25 processors can scan racks 01-07 PLC-5/40 and 5/60 processors can scan racks 01-17

Each block uses 2 words of output image table memory and 2 words of
input image table memory. Each block occupies 1/4 rack of data table, with
4 blocks comprising 1 logical rack. Image table usage for one assigned
rack number is shown in Figure 4.2 (IOBA) and Figure 4.4 (IOBB). An
example of image table usage is shown in Figure 4.3 (IOBA) and
Figure 4.5 (IOBB).

43

Chapter 4

Configuring Your Block I/O for PLC
Family Programmable Controllers

Figure 4.2

Image T

I/O

able for One Assigned Rack Number with 1791-IOBA

Input Image

710

0
1
2
3
4
5
6
7

Reserved

Reserved

Reserved

Reserved

Reserved

Reserved

Reserved

Reserved

017

Figure 4.3

T

able Usage Example for One Starting I/O Group with 1791-IOBA

Input

Example

T

ype of I/O

1 = Input
0 = Output

I/O Rack Number

1791-IOBA1791-IOBA1791-IOBA1791-IOBA

11000

Rack 1

0
1
2
3
4
5
6
7

For 1791-IOBA - 7-0 input and 7-0 output image bits

Reserved

Reserved

Reserved

Reserved

Output Image

710

Reserved

Reserved

Reserved

Reserved

017

I/O Bit

I/O Group Number

10837-I

44

Starting

I/O Group

0

110

111

010

011

Reserved

Reserved

Reserved

11107654321

Block Data

Reserved

11 10

7654321

Block Data

0

0

Input

Image

Output Image

10838-I

Figure 4.4
I/O Image T

Chapter 4

Configuring Your Block I/O for PLC
Family Programmable Controllers

able for One Assigned Rack Number with 1791-IOBB

Input Image

710

0
1
2
3
4
5
6
7

Reserved

Reserved

Reserved

Reserved

Reserved

Reserved

Reserved

Reserved

017

Figure 4.5
Input

Example

Type

of I/O

1 = Input
0 = Output

I/O Rack Number

1791-IOBB1791-IOBB1791-IOBB1791-IOBB

T

able Usage Example for One Starting I/O Group with 1791-IOBB

1 I/O Rack

0
1
2
3
4
5
6
7

For 1791-IOBB - 11-0 input and 5-0 output image bits

Output Image

710

Reserved

Reserved

Reserved

Reserved

Reserved

Reserved

Reserved

Reserved

11200

I/O Bit

I/O Group Number

017

Starting

Group

I/O

112

113

012

2

013

Reserved

Reserved

Reserved

11107654321

Block Data

Reserved

11 10 7 6

54321

Block Data

0

0

Input Image

Output Image

45

Chapter 4

Configuring Your Block I/O for PLC
Family Programmable Controllers

Summary

In this chapter you learned how to set the configuration switches and
address the block I/O. You also learned about input and output image use
in memory.

46

Chapter

5

Configuring Your Block I/O for SLC
Controllers

Chapter

Setting the Configuration Switches

Objectives

In this chapter you will learn to identify block I/O switches and their
position.

Refer to publication 1747–ND012, Distributed I/O Scanner and Block, for
complete information on switch settings and addressing of the block I/O.

Each block I/O module has two 6–position DIP switches for setting:

block address
transmission (baud) rate
last state or reset
DH–485 termination

These switches are accessible by opening the door on the left side of the
module (Figure 5.1).

51

Chapter 5

Configuring Your Block I/O for
SLC Controllers

S1 S2

Figure 5.1

Settings for Block I/O when used with the SLC 500 Controller

Switch

Block
Addresses

1-7
1-15

17-31

Switches
1 - 6

100000 to 111000

100000 to 111100

100010 to 111110

OUTPUT

INPUT

S1 S2

OPEN

12 3456

Switch as viewed from this end.

Off = Open = 1

12 3456

OPEN

Not Used

COMM POWER

230.4K

Reset to 0

Hold last state

Terminate

None

56Baud Rate

On (0)

4Hold Last State

Off (1)

On (0)

1DH-485

On (0)

Off (1)

Off (1)

52

On = Closed = 0

10839-I

Chapter 5

Configuring Your Block I/O for
SLC Controllers

Table 5.A

Addresses for Block I/O Used with SLC 500 Controllers

Block

Block Switch S1 Positions Block Switch S1 Positions

Address 1 2 3 4 5 6 Address 1 2 3 4 5 6

1 Off (1) On (0) On (0) On (0) On (0) On (0) 17 Off (1) On (0) On (0) On (0) Off (1) On (0)

2 On (0) Off (1) On (0) On (0) On (0) On (0) 18 On (0) Off (1) On (0) On (0) Off (1) On (0)

3 Off (1) Off (1) On (0) On (0) On (0) On (0) 19 Off (1) Off (1) On (0) On (0) Off (1) On (0)

4 On (0) On (0) Off (1) On (0) On (0) On (0) 20 On (0) On (0) Off (1) On (0) Off (1) On (0)

5 Off (1) On (0) Off (1) On (0) On (0) On (0) 21 Off (1) On (0) Off (1) On (0) Off (1) On (0)

6 On (0) Off (1) Off (1) On (0) On (0) On (0) 22 On (0) Off (1) Off (1) On (0) Off (1) On (0)

7 Off (1) Off (1) Off (1) On (0) On (0) On (0) 23 Off (1) Off (1) Off (1) On (0) Off (1) On (0)

8 On (0) On (0) On (0) Off (1) On (0) On (0) 24 On (0) On (0) On (0) Off (1) Off (1) On (0)

9 Off (1) On (0) On (0) Off (1) On (0) On (0) 25 Off (1) On (0) On (0) Off (1) Off (1) On (0)

10 On (0) Off (1) On (0) Off (1) On (0) On (0) 26 On (0) Off (1) On (0) Off (1) Off (1) On (0)

11 Off (1) Off (1) On (0) Off (1) On (0) On (0) 27 Off (1) Off (1) On (0) Off (1) Off (1) On (0)

12 On (0) On (0) Off (1) Off (1) On (0) On (0) 28 On (0) On (0) Off (1) Off (1) Off (1) On (0)

13 Off (1) On (0) Off (1) Off (1) On (0) On (0) 29 Off (1) On (0) Off (1) Off (1) Off (1) On (0)

14 On (0) Off (1) Off (1) Off (1) On (0) On (0) 30 On (0) Off (1) Off (1) Off (1) Off (1) On (0)

15 Off (1) Off (1) Off (1) Off (1) On (0) On (0) 31 Off (1) Off (1) Off (1) Off (1) Off (1) On (0)

16 Invalid

Addressing the Blocks Using SLC Controllers

The SLC controller communicates with the block I/O using a Distributed
I/O Scanner module (cat. no. 1747–DSN). The scanner can address up to 7
blocks using an SLC 5/01 Controller, and up to 30 blocks using an SLC
5/02 Controller. When used with the Distributed I/O Scanner module,
block addresses must be contiguous. The actual number of blocks to which
the scanner module will communicate is determined when programming
the SLC controller.

Refer to the 1747–DSN Scanner module user’s manual for more
information.

Summary

In this chapter you learned how to identify and set the configuration
switches on the block.

53

Troubleshooting

Chapter

6

Chapter Objectives

LED Indicators

In this chapter you will learn about the LED indicators on the block I/O
module, and how to use them to troubleshoot the unit.

Each block I/O module has LED indicators (Figure 6.1) which provide
indication of specific functions. Each module has the following:

green communication indicator – indicates whether communication is

occurring between processor or scanner and the block.

red power indicator – indicates if power is applied to module and

internal hardware status

16 I/O status indicators (8 input–8 output or 10 input–6 output) – reflect

the state of the individual inputs and outputs (on or off)

The location of the indicators is shown in Figure 6.1. Refer to Table 6.A
for status indications reported by the indicators.

Figure 6.1
Indicators

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

Communication LED (green)Power LED (red)Status Indicators

OUTPUT

INPUT

COMMPOWER

10846-I

61

Chapter 6

Troubleshooting

Table 6.A
Troubleshooting

Indication Probable Cause Corrective Action

Green COMM LED on
Red POWER LED on
I/O status LED on/off

Red POWER LED flashing Block failed self-test, or a major fault is detected. Cycle power to the block. If problem persists,

Red POWER LED off No 24V dc power connected, or hardware fault. Check 24V dc power to block

Green COMM LED off No communication with processor, scanner etc. Check that power LED is on. Make sure that

Green COMM LED flashing Reset command (or output disable bit for SLC) has

Summary

Normal indication None required

been issued by processor or scanner.

SLC or programmable controller not in run mode. Place in run mode.

In this chapter you learned about the LED indicators and how to use them

Chart

replace the block.

proper number of blocks are configured.

Check program. Correct as necessary.

to troubleshoot the block I/O module.

62

Specifications

General Specifications

Appendix

A

External power

Environmental Conditions

Operating Temperature
Storage Temperature
Relative Humidity

Conductors Wire Size 14 gauge stranded (maximum)

Power Dissipation IOBA: 13.42 Watts (maximum); 9.46 Watts (typical)

Thermal Dissipation IOBA: 45.9 BTU/hr (maximum); 32.4 BTU/hr (typical)

Remote I/O Isolation 850V dc (transformer) for 1 second

DH-485 Isolation 850V dc (optocoupler) for 1 second

Interconnect cable length RIO: PLC 57.6K 10,000 cable-feet

Cable requirements RIO/DIO - Belden 9463

1791-IOBA Input Specifications

200mA @ 24V dc; initial surge 5.5A for 10µsec

32 to 131oF (0 to 55oC)

-40 to 185
5 to 95% noncondensing

3/64 inch insulation (maximum)

IOBB: 12.39 Watts (maximum); 8.73 Watts (typical)

IOBB: 42.4 BTU/hr (maximum); 29.8 BTU/hr (typical)

DH-485 4000 ft (1219 meters)

DH-485 - Belden 9842

o

F (-40 to 85oC)

115.2K 5,000 cable-feet

230.4K 2,500 cable-feet

SLC 230.4K 2,500 cable-feet

Number of Inputs 8

Input type Sinking

Input voltage range 20.5 to 27.6V dc

On-state input current 6.3mA (minimum)

On-state input voltage 20.5V dc (minimum)

Off-state voltage 5.1V dc (maximum)

Off-state current 1mA dc (maximum)

Turn On time 1.5msec (maximum)

Turn Off time 1.0msec (maximum)

A1

Appendix A

Specifications

1791-IOBA Output Specifications

Number of outputs 8

Output type Source

Rated output voltage 10 to 30V dc

Maximum on-state voltage drop 1.5V dc @ 25oC

Maximum on-state current 0.5A

Minimum on-state current 15mA

Surge Current 3.0A for 10ms (maximum), 1 pulse per second max.

Off-state voltage 30V dc (maximum)

Off-state leakage current 0.5mA (maximum)

Turn on time 0.5ms (maximum)

Turn off time 1ms (maximum)

1791-IOBB Input Specifications

Number of Inputs 10

Input type Sinking

Input voltage 20.5 to 27.6V dc

On-state input voltage 20.5V dc (minimum)

On-state input current 6.3mA (minimum)

Off-state voltage 5.1V dc

Off-state current 1mA dc

Turn On time 1.5msec (maximum)

Turn Off time 1.0msec (maximum)

A2

Appendix A

Specifications

1791-IOBB Output Specifications

Number of outputs 6

Output type Source

Rated output voltage 10 to 30V dc

Maximum on-state voltage drop 1.5V dc @ 25oC

Maximum on-state current 0.5A

Minimum on-state current 15mA

Surge Current (maximum) 3.0A for 10ms (max), 1 pulse per second max.

Off-state voltage 30V dc (maximum)

Off-state leakage current 0.5mA (maximum)

Turn on time 0.5ms (maximum)

Turn off time 1ms (maximum)

A3

Index

B

block addressing, SLC, 53

C

combinations, acceptable processor and

block I/O, 31

compatibility, extended node numbers, 39

configuration switches, 41

SLC, 51

connecting block I/O, in a PLC system, 23

connecting wiring, 33

1791-IOBA, 33
1791-IOBB, 34

D

description, 21

DH-485 port, 22

E

extended node capability, 38

F

M

mounting dimensions, 32

P

power supply requirements, 35

R

related publications, 12

remote I/O link connector, 22

remote I/O link wiring, 36

S

series connections

PLC-2, PLC-3 and PLC-5, 36
SLC, 37

sinking inputs, 22

description, 22

sourcing outputs, 22

description, 22

specifications, A1

status indicators, 22

switch assemblies, 22

features, 21

I

I/O rack addressing

PLC-2 family, 42
PLC-3 and PLC-5/250, 43
PLC-5, 43

image table usage, 43

1791-IOBA, 44
1791-IOBB, 45

L

LED indicators, 61

T

termination resistor, 38

troubleshooting chart, 62

types of block I/O, 21

W

wiring cable, 35

wiring connections, definitions, 34

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Publication 1791–6.5.1 – November 1991

Supersedes publication 1791–6.5.1 – August 1991 and 1791–6.5.1–DU1 – July 1991

Copyright 1991 Allen-Bradley Company, Inc. Printed in USA

P/N 955110–93