Rockwell Automation Allen-Bradley ControlLogix 1756-HSC User manual

ControlLogix High
Speed Counter
M odule
1756-HSC
User M anual

Important User Information
Because of the variety of uses for the products described in this
publication, those responsible for the application and use of this
control equipment must satisfy themselves that all necessary steps
have been taken to assure that each application and use meets all
performance and safety requirements, including any applicable laws,
regulations, codes and standards.
The illustrations, charts, sample programs and layout examples shown
in this guide are intended solely for purposes of example. Since there
are many variables and requirements associated with any particular
installation, Allen-Bradley does not assume responsibility or liability
(to include intellectual property liability) for actual use based upon
the examples shown in this publication.
Allen-Bradley publication SGI-1.1, Sa fety Guidelines for the
Applica tion, Insta lla tion a nd Ma intena nce of Solid-Sta te Control
(available from your local Allen-Bradley office), describes some
important differences between solid-state equipment and
electromechanical devices that should be taken into consideration
when applying products such as those described in this publication.
Reproduction of the contents of this copyrighted publication, in whole
or part, without written permission of Rockwell Automation, is
prohibited.
Throughout this manual we use notes to make you aware of safety
considerations:
Attention statements help you to:
•identify a hazard
•avoid a hazard
•recognize the consequences
Allen-Bradley is a trademark of Rockwell Automation
ATTENTION
!
Identifies information about practices or
circumstances that can lead to personal injury or
death, property damage or economic loss
IM PORTANT Identifies information that is critical for successful
application and understanding of the product.

European Communities (EC)
Directive Compliance
If this product has the CE mark it is approved for installation within
the European Union and EEA regions. It has been designed and
tested to meet the following directives.
EM C Directive
This product is tested to meet the Council Directive 89/336/EC
Electromagnetic Compatibility (EMC) by applying the following
standards, in whole or in part, documented in a technical
construction file:
•EN 50081-2 EMC — Generic Emission Standard, Part 2 —
Industrial Environment
•EN 50082-2 EMC — Generic Immunity Standard, Part 2 —
Industrial Environment
This product is intended for use in an industrial environment.
Low Voltage Directive
This product is tested to meet Council Directive 73/23/EEC Low
Voltage, by applying the safety requirements of EN 61131-2
Programmable Controllers, Part 2 - Equipment Requirements and
Tests. For specific information required by EN 61131-2, see the
appropriate sections in this publication, as well as the Allen-Bradley
publication Industrial Automation Wiring and Grounding Guidelines
For Noise Immunity, publication 1770-4.1.
Open style devices must be provided with environmental and safety
protection by proper mounting in enclosures designed for specific
application conditions. See NEMA Standards publication 250 and IEC
publication 529, as applicable, for explanations of the degrees of
protection provided by different types of enclosure.

Rockw ell Automation
Support
Rockwell Automation offers support services worldwide, with over 75
sales/support offices, 512 authorized distributors and 260 authorized
systems integrators located throughout the United States alone, as well
as Rockwell Automation representatives in every major country in the
world.
Local Product Support
Contact your local Rockwell Automation representative for:
•sales and order support
•product technical training
•warranty support
•support service agreements
Technical Product Assistance
If you need to contact Rockwell Automation for technical assistance,
please review the troubleshooting information in Appendix A first. If
the problem persists, then call your local Rockwell Automation
representative.
Your Questions or Comments on this M anual
If you find a problem with this manual, please notify us of it on the
enclosed Publication Problem Report.

5Publication 1756-UM 007A-EN-P - October 2000
Summary of Changes
Introduction
This release of this document contains new information.
New Information
New information is marked by Change Bars in the side column, as
shown to the left. lists sections that contain new information.
Section: Changes
Chapter 3 Additional information about module features
Chapter 4 Updated wiring diagram for connection to an
Allen-Bradley Bulletin 872 3-W ire DC Proximity Sensor
Chapter 5 Configuration information
Appendix A Specification changes
Appendix B New application considerations

Publication 1756-UM 007A-EN-P - October 2000
Summary of Changes 6
Notes:

1Publication 1756-UM 007A-EN-P - October 2000
Preface
What This Preface Contains
This preface describes how to use this manual. The following table
describes what this preface contains and its location.
Who Should Use This
M anual
You must be able to program and operate an Allen-Bradley
ControlLogix ™ Logix5550 Controller and various Allen-Bradley
encoders and sensors to efficiently use your ControlLogix High Speed
Counter module.
In this manual, we assume that you know how to use these products.
If you do not, refer to the related user publications for each product,
before you attempt to use the High Speed Counter module.
Purpose of This M anual
This manual describes how to install, configure, use, and troubleshoot
your ControlLogix High Speed Counter module.
For information about: See page:
Who Should Use This Manual Preface-1
Purpose of This Manual Preface-1
Related Terms Preface-2
Related Products and Documentation Preface-3
IM PORTANT In the rest of this manual, we refer to the
ControlLogix High Speed Counter module as the
HSC module.

Publication 1756-UM 007A-EN-P - October 2000
Preface 2
Related Terms
This manual uses the following terms:
This term: Means:
Broadcast Data transmissions to all addresses
Communications
format
Format that defines the type of information transferred between an
I/O module and its owner controller. This format also defines the
tags created for each I/O module
Compatible match An electronic keying protection mode that requires the physical
module and the module configured in the software to match
according to vendor, catalog number and major revision. In this
case, the minor revision of the module must be greater than or
equal to that of the configured slot
Connection The communication mechanism from the controller to another
module in the control system
ControlBus The backplane used by the 1756 chassis
Coordinated
System Time
(CST)
Timer value which is kept synchronized for all modules within a
single ControlBus chassis. The CST is a 64 bit number with µs
resolution
Direct connection An I/O connection where the controller establishes an individual
connection with I/O modules
Disable keying Option that turns off all electronic keying to the module. Requires
no attributes of the physical module and the module configured in
the software to match
Download The process of transferring the contents of a project on the
workstation into the controller
Electronic keying A system feature which makes sure that the physical module
attributes are consistent with what was configured in the software
Exact match An electronic keying protection mode that requires the physical
module and the module configured in the software to match
identically, according to vendor, catalog number, major revision and
minor revision
Field side Interface between user field wiring and I/O module
Inhibit A ControlLogix process that allows you to configure an I/O module
but prevent it from communicating with the owner controller. In
this case, the controller does not establish a connection
Listen-only
connection
An I/O connection that allows a controller to monitor I/O module
data without owning the module
Major revision A module revision that is updated any time there is a functional
change to the module resulting in an interface change with
software
Minor revision A module revision that is updated any time there is a change to the
module that does not affect its function or software user interface
(e.g. bug fix)
Multicast Data transmissions which reach a specific group of one or more
destinations
Network update
time (NUT)
The smallest repetitive time interval in which the data can be sent
on a ControlNet network. The NUT may be configured over the
range from 2ms to 100ms using RSNetWorx

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Preface 3
Related Products and
Documentation
The following table lists related ControlLogix products and
documentation:
If you need more information on these products, contact your local
Allen-Bradley integrator or sales office for assistance. For more
information on the documentation, refer to the Allen-Bradley
Publication Index, publication SD499.
Owner controller The controller that creates and stores the primary configuration and
communication connection to a module
Producer/consum
er
Intelligent data exchange system devices in which the HSC module
produces data without having been polled first
Program mode In this mode, the controller program is not executing.
Inputs are actively producing data.
Outputs are not actively controlled and go to their configured
program mode state
Remote
connection
An I/O connection where the controller establishes an individual
connection with I/O modules in a remote chassis
Removable
terminal block
(RTB)
Field wiring connector for I/O modules
Removal and
insertion under
power (RIUP)
ControlLogix feature that allows a user to install or remove a
module or RTB while power is applied
Requested packet
interval (RPI)
A configurable parameter which defines when the module will
multicast data
Run mode In this mode, the controller program is executing
Inputs are actively producing data.
Outputs are actively controlled
Service A system feature that is performed on user demand
System side Backplane side of the interface to the I/O module
Tag A named area of the controller’s memory where data is stored
like a variable
Cat. number: Document title: Pub.
number:
1756-PA72/B,
-PB72/B
ControlLogix Power Supply Installation Instructions 1756- 5.67
1756-PA75/A,
-PB75/A
ControlLogix Power Supply Installation Instructions 1756- 5.78
1756-A4, -A7,
-A10, -A13,
-A17
ControlLogix Chassis Installation Instructions 1756-5.80
1756 Series ControlLogix System User Manual 1756-UM001
ControlLogix Digital I/O Modules User Manual 1756-6.5.8
ControlLogix Analog I/O Modules User Manual 1756-6.5.9

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Preface 4
Notes:

iPublication 1756-UM 007A-EN-P - October 2000
Table of Contents
Chapter 1
What is the ControlLogix
High Speed Counter M odule?
What This Chapter Contains . . . . . . . . . . . . . . . . . . . . . . . 1-1
What is the ControlLogix High Speed Counter Module? . . . 1-1
Purpose of the HSC Module . . . . . . . . . . . . . . . . . . . . . 1-2
Using An High Speed Counter Module
in the ControlLogix System . . . . . . . . . . . . . . . . . . . . . . . . 1-3
Features of the ControlLogix High Speed
Counter Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
Preventing Electrostatic Discharge . . . . . . . . . . . . . . . . . . . 1-4
Removal and Insertion Under Power . . . . . . . . . . . . . . . . . 1-5
Chapter Summary and What’s Next . . . . . . . . . . . . . . . . . . 1-5
Chapter 2
High Speed Counter Operation
W ithin the ControlLogix System
What This Chapter Contains . . . . . . . . . . . . . . . . . . . . . . . 2-1
Ownership and Connections . . . . . . . . . . . . . . . . . . . . . . . 2-1
Using RSNetWorx and RSLogix 5000 . . . . . . . . . . . . . . . . . 2-2
Enabling HSC Module Operation in a Remote Chassis . . 2-2
Direct Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
High Speed Counter Module Operation . . . . . . . . . . . . . . . 2-3
High Speed Counter Modules in a Local Chassis. . . . . . . . . 2-4
Requested Packet Interval (RPI) . . . . . . . . . . . . . . . . . . 2-4
High Speed Counter Modules in a Remote Chassis . . . . . . . 2-5
Listen-Only Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
Chapter Summary and What’s Next . . . . . . . . . . . . . . . . . . 2-6
Chapter 3
ControlLogix High Speed
Counter M odule Features
and I/O Operation
What this Chapter Contains . . . . . . . . . . . . . . . . . . . . . . . . 3-1
Determining Encoder and Sensor Compatibility . . . . . . . . . 3-1
Features of the ControlLogix High Speed Counter Module . 3-2
Removal and Insertion Under Power (RIUP) . . . . . . . . . 3-2
Module Fault Reporting . . . . . . . . . . . . . . . . . . . . . . . . 3-2
Fully Software Configurable . . . . . . . . . . . . . . . . . . . . . 3-2
Electronic Keying. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3
Producer/Consumer Model. . . . . . . . . . . . . . . . . . . . . . 3-4
LED Status Information. . . . . . . . . . . . . . . . . . . . . . . . . 3-4
Full Class I Division 2 Compliance . . . . . . . . . . . . . . . . 3-4
CE/CSA/UL Agency Certification . . . . . . . . . . . . . . . . . . 3-4
Operation in Encoder or Counter Mode . . . . . . . . . . . . . . . 3-5
Counter Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6
Encoder Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7
Preset Value . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9
Rollover Value . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9
Software Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-10
Gate/Reset Input (Z) . . . . . . . . . . . . . . . . . . . . . . . . . . 3-10
Store Count . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-10

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Table of Contents ii
Operation in Rate Measurement Mode . . . . . . . . . . . . . . . . 3-12
Sample Period . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-13
Connection to Channel Inputs . . . . . . . . . . . . . . . . . . . 3-13
Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-13
Controlling the ON/OFF Output Status . . . . . . . . . . . . . 3-14
Manual Override of Outputs. . . . . . . . . . . . . . . . . . . . . 3-15
Assigning Outputs to Counters . . . . . . . . . . . . . . . . . . . 3-15
Operation of Outputs. . . . . . . . . . . . . . . . . . . . . . . . . . 3-15
Handshaking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-16
Module Maximum Frequency . . . . . . . . . . . . . . . . . . . . 3-17
Chapter Summary and What’s Next . . . . . . . . . . . . . . . . . . 3-17
Chapter 4
Installing and Wiring the
ControlLogix High Speed
Counter M odule
What this Chapter Contains . . . . . . . . . . . . . . . . . . . . . . . . 4-1
Installing the ControlLogix High Speed Counter Module . . . 4-1
Keying the Removable Terminal Block. . . . . . . . . . . . . . . . 4-3
Connecting Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4
Connect Grounded End of the Cable . . . . . . . . . . . . . . 4-4
Connect Ungrounded End of the Cable. . . . . . . . . . . . . 4-5
Two Types of RTBs (each RTB comes with housing) . . . 4-5
Recommendations for Wiring Your RTB . . . . . . . . . . . . 4-6
Cable Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6
Wiring Terminations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8
Wiring an Allen-Bradley 845 Incremental Encoder. . . . . 4-8
Wiring an Allen-Bradley Bulletin 872
3-Wire DC Proximity Sensor . . . . . . . . . . . . . . . . . . . . . 4-9
Wiring a Photoswitch Series 10,000 Photoelectric Sensor 4-10
Assembling The Removable Terminal Block
and the Housing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-11
Installing the Removable Terminal Block onto the Module . 4-12
Removing the Removable Terminal Block from the Module 4-13
Removing the Module from the Chassis . . . . . . . . . . . . . . . 4-14
Chapter Summary and What’s Next . . . . . . . . . . . . . . . . . . 4-14
Chapter 5
Configuring the ControlLogix
High Speed Counter M odule
What This Chapter Contains . . . . . . . . . . . . . . . . . . . . . . . 5-1
Configuring Your High Speed Counter Module. . . . . . . . . . 5-1
RSLogix 5000 Configuration Software . . . . . . . . . . . . . . 5-1
Overview of the Configuration Process . . . . . . . . . . . . . . . 5-2
Using the Default Configuration . . . . . . . . . . . . . . . . . . 5-2
Altering the Default Configuration . . . . . . . . . . . . . . . . 5-2
Creating a New Module. . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3
Communications Format. . . . . . . . . . . . . . . . . . . . . . . . 5-6
Electronic Keying. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7
High Speed Counter Data Structures . . . . . . . . . . . . . . . 5-7

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Table of Contents iii
Accessing the Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-17
Changing Configuration Information at the Tags. . . . . . . . . 5-18
Configurable Features . . . . . . . . . . . . . . . . . . . . . . . . . 5-18
Downloading Configuration Data. . . . . . . . . . . . . . . . . . . . 5-19
Changing Configuration During HSC Module Operation . . . 5-20
Using Ladder Logic . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-20
Using Message Instructions . . . . . . . . . . . . . . . . . . . . . . . . 5-22
Processing Real-Time Control and Module Services . . . . 5-22
One Service Performed Per Instruction . . . . . . . . . . . . . 5-22
Creating a New Tag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-23
Enter Message Configuration . . . . . . . . . . . . . . . . . . . . 5-24
Configuring HSC Modules in a Remote Chassis. . . . . . . . . . 5-26
Chapter Summary and What’s Next . . . . . . . . . . . . . . . . . . 5-28
Chapter 6
Troubleshooting Your M odule
What This Chapter Contains . . . . . . . . . . . . . . . . . . . . . . . 6-1
Using Indicators to Troubleshoot Your Module . . . . . . . . . 6-1
LED indicators for the HSC module . . . . . . . . . . . . . . . 6-1
Using RSLogix 5000 to Troubleshoot Your Module . . . . . . . 6-2
Determining Fault Type . . . . . . . . . . . . . . . . . . . . . . . . 6-4
Solving Common Problems
in High Speed Counter Applications . . . . . . . . . . . . . . . . . 6-4
Chapter Summary and What’s Next . . . . . . . . . . . . . . . . . . 6-5
Appendix A
Specifications
1756-HSC Specifications . . . . . . . . . . . . . . . . . . . . . . . . A-1
Appendix B
Application Considerations
Appendix Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1
Types of Input Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1
Examples for Selecting Input Devices. . . . . . . . . . . . . . . . . B-2
Circuit Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-2
Detailed Circuit Analysis. . . . . . . . . . . . . . . . . . . . . . . . B-3
5V Differential Line Driver Example . . . . . . . . . . . . . . . B-4
+12 to +24V Single_Ended Driver . . . . . . . . . . . . . . . . . B-5
Open Collector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-6
Electromechanical Limit Switch. . . . . . . . . . . . . . . . . . . B-7
Output Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-8
Application Considerations . . . . . . . . . . . . . . . . . . . . . . . . B-9
Input Cable Length . . . . . . . . . . . . . . . . . . . . . . . . . . . B-9
Totem-pole Output Devices . . . . . . . . . . . . . . . . . . . . . B-9
Cable Impedance . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-10
Cable Capacitance . . . . . . . . . . . . . . . . . . . . . . . . . . . B-10
Cable Length and Frequency . . . . . . . . . . . . . . . . . . . B-10
Index

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Table of Contents iv

1Publication 1756-UM 007A-EN-P - October 2000
Chapter 1
What is the ControlLogix
High Speed Counter M odule?
What This Chapter Contains
This chapter describes the ControlLogix HSC module and what you
must know and do before you begin to use it.
What is the ControlLogix
High Speed Counter
M odule?
The ControlLogix HSC module is an intelligent I/O module providing
four high speed output switching, ON-OFF windows, and using
pulses from quadrature encoders, pulse generators, proximity
switches and other similar products for counting or frequency.
These high speed digital outputs are dedicated to one of two
rotational position sensors and not affected by any changes occurring
in the ControlLogix controller. The module outputs provide consistent
switch ON and switch OFF times for repeatable speed compensation.
Using the producer/consumer network model, controllers can
produce information for any controller that may use it. A single
encoder may drive multiple modules as long as it provides the
minimum current required for each module.
The HSC is a single-slot module that requires a separate external
power supply for its outputs. For more information on specific voltage
and current requirements, see the specifications listed in Appendix A.
For information about: See page:
What is the ControlLogix High Speed
Counter Module?
1-1
Using An High Speed Counter M odule in the
ControlLogix System
1-3
Features of the ControlLogix High Speed
Counter Modules
1-3
Preventing Electrostatic Discharge 1-4
Removal and Insertion Under Power 1-5
Chapter Summary and What’s Next 1-5

Publication 1756-UM 007A-EN-P - October 2000
1-2 What is the ControlLogix High Speed Counter M odule?
High speed inputs, as found on the HSC module, may be sensitive to
electromagnetic noise. The module contains opto-isolators that
minimize the effects of noise, but you should provide grounding
methods that keep noise spikes under 2000V for backplane
(ControlBus) protection and under 1000V for channel-to-channel
protection.
The following is a list of the features available on the ControlLogix
HSC module:
•Removal and insertion under power (RIUP) - a system feature
that allows you to remove and insert modules while chassis
power is applied
•Operation in any of the following modes: Counter, Encoder X1,
Quadrature Encoder (Encoder X4) or Rate Measurement
Frequency - each mode allows the HSC module to operate with
a specific maximum frequency
•Two configurable channels with up to 3 single-ended or
differential (user-defined) inputs per channel
•Four current-sourcing outputs at 5-30V dc with 1A maximum per
output that can turn ON and OFF within 300µs
•Class I/Division 2, UL, CSA, and CE Agency Certification
Purpose of the HSC M odule
The most common use for the HSC Module is to interface 1 or 2
incremental encoders to the ControlLogix platform. It can also be
used to count high speed pulse streams from 1 or 2 discrete devices
such as a proximity or photoelectric control.
IM PORTANT The HSC module must reside in the same chassis as
the Logix5550 controller for maximum performance
with the controller.

Publication 1756-UM 007A-EN-P - October 2000
What is the ControlLogix High Speed Counter M odule? 1-3
Using An High Speed
Counter M odule in the
ControlLogix System
An HSC module performs high speed counting for industrial
applications. The module interfaces with a ControlLogix Logix5550
controller to report the number of counts at each frequency.
A ControlLogix HSC module mounts in a ControlLogix chassis and
uses a Removable Terminal Block (RTB) to connect all field-side
wiring.
Before you install and use your module you should have already:
•installed and grounded a 1756 chassis and power supply. To
install these products, refer to publications 1756-5.67, 1756-5.78
and 1756-5.80.
•ordered and received an RTB and its components. RTBs are not
included with your module purchase.
Features of the ControlLogix High Speed Counter M odules
IM PORTANT A grounded 1756 chassis is not sufficient to minimize
encoder noise. You should use continuous overall
shielded cable that is properly grounded to a signal
ground. The signal ground must be separate from
the AC earth ground used to protect personnel.
Removable
Terminal
Block
ControlLogix HSC M odule
Indicators
Locking tab
Slots for
keying the
RTB
Connector
pins
Top and
bottom
guides
ControlBus™
Connector
41623

Publication 1756-UM 007A-EN-P - October 2000
1-4 What is the ControlLogix High Speed Counter M odule?
ControlBus connector - The backplane interface for the
ControlLogix system connects the module to the ControlBus
backplane.
Connectors pins - Input/output, power and grounding connections
are made to the module through these pins with the use of an RTB.
Locking tab - The locking tab anchors the RTB on the module,
maintaining wiring connections.
Slots for keying - Mechanically keys the RTB to prevent
inadvertently making the wrong wire connections to your module.
Status indicators - Indicators display the status of communication,
module health and presence of input/output devices. Use these
indicators to help in troubleshooting.
Top and bottom guides - Guides provide assistance in seating the
RTB onto the module.
Preventing Electrostatic
Discharge
This module is sensitive to electrostatic discharge when handled
outside of the chassis. The module has been tested to withstand an
electrostatic discharge while operating within the chassis.
ATTENTION
!
Electrostatic discharge can damage
integrated circuits or semiconductors if you touch
backplane connector pins. Follow these guidelines
when you handle the module:
•Touch a grounded object to discharge static
potential
•Wear an approved wrist-strap grounding device
•Do not touch the backplane connector or
connector pins
•Do not touch circuit components inside the
module
•If available, use a static-safe work station
•When not in use, keep the module in its
static-shield box

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What is the ControlLogix High Speed Counter M odule? 1-5
Removal and Insertion
Under Pow er
These modules are designed to be installed or removed while chassis
power is applied.
Chapter Summary
and W hat’s Next
In this chapter you learned about:
•what the ControlLogix HSC module is
•using the HSC module in the ControlLogix system
•preventing electrostatic discharge
•removing and inserting the module under power
Move on to Chapter 2 to learn about High Speed Counter operation
within the ControlLogix system.
ATTENTION
!
When you insert or remove a module while
backplane power is applied, an electrical arc may
occur. An electrical arc can cause personal injury
or property damage by:
•sending an erroneous signal to your system’s
field devices causing unintended machine
motion or loss of process control.
•causing an explosion in a hazardous
environment.
Repeated electrical arcing causes excessive wear to
contacts on both the module and its mating
connectors. Worn contacts may create electrical
resistance that can affect module operation.

Publication 1756-UM 007A-EN-P - October 2000
1-6 What is the ControlLogix High Speed Counter M odule?
Notes: