Rockwell Automation 1756-HSC User Manual
User Manual
ControlLogix High-speed Counter Module
Catalog Numbers 1756-HSC
Important User Information
IMPORTANT
Solid-state equipment has operational characteristics differing from those of electromechanical equipment. Safety
Guidelines for the Application, Installation and Maintenance of Solid State Controls (publication SGI-1.1
your local Rockwell Automation® sales office or online at http://www.rockwellautomation.com/literature/
important differences between solid-state equipment and hard-wired electromechanical devices. Because of this difference,
and also because of the wide variety of uses for solid-state equipment, all persons responsible for applying this equipment
must satisfy themselves that each intended application of this equipment is acceptable.
In no event will Rockwell Automation, Inc. be responsible or liable for indirect or consequential damages resulting from the
use or application of this equipment.
The examples and diagrams in this manual are included solely for illustrative purposes. Because of the many variables and
requirements associated with any particular installation, Rockwell Automation, Inc. cannot assume responsibility or
liability for actual use based on the examples and diagrams.
No patent liability is assumed by Rockwell Automation, Inc. with respect to use of information, circuits, equipment, or
software described in this manual.
Reproduction of the contents of this manual, in whole or in part, without written permission of Rockwell Automation,
Inc., is prohibited.
Throughout this manual, when necessary, we use notes to make you aware of safety considerations.
available from
) describes some
WARNING: Identifies information about practices or circumstances that can cause an explosion in a hazardous environment,
which may lead to personal injury or death, property damage, or economic loss.
ATTENTION: Identifies information about practices or circumstances that can lead to personal injury or death, property
damage, or economic loss. Attentions help you identify a hazard, avoid a hazard, and recognize the consequence.
SHOCK HAZARD: Labels may be on or inside the equipment, for example, a drive or motor, to alert people that dangerous
voltage may be present.
BURN HAZARD: Labels may be on or inside the equipment, for example, a drive or motor, to alert people that surfaces may
reach dangerous temperatures.
Identifies information that is critical for successful application and understanding of the product.
Allen-Bradley, Rockwell Software, Rockwell Automation, ControlLogix, RSLogix , Logix5000, PHOTOSWITCH, RSNetWorx, and TechConnect are trademarks of Rockwell Automation, Inc.
Trademarks not belonging to Rockwell Automation are property of their respective companies.
Summary of Changes
This manual contains new and updated information. Changes throughout this
revision are marked by change bars, as shown to the right of this paragraph.
New and Updated Information
This table contains the changes made to this revision.
Topic Page
The Attention and Warning tables have been updated. 39
Rockwell Automation Publication 1756-UM007C-EN-P - November 2011
4 Summary of Changes
Notes:
Rockwell Automation Publication 1756-UM007C-EN-P - November 2011
Table of Contents
Preface
1756-HSC Module Features
Counter Modes
About This Publication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Who Should Use This Manual. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Additional Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Chapter 1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
What is a High-speed Counter Module? . . . . . . . . . . . . . . . . . . . . . . . . 11
Encoder and Sensor Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
1756-HSC/B Module Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Additional I/O Module Features . . . . . . . . . . . . . . . . . . . . . . . . . . 14
1756-HSC Parts Illustration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Chapter 2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Counter/Encoder Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Counter Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Encoder Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Preset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Rollover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Input Z (Gate/Reset) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Storage Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Outputs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Assign Outputs to Counters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Output Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Frequency Modes
Install and Wire the ControlLogix
High-speed Counter Module
Chapter 3
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Frequency Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Frequency Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Sample Period for Frequency Mode . . . . . . . . . . . . . . . . . . . . . . . . 31
Period Rate and
Continuous Rate Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Sample Period for Period/Continuous Rate Modes . . . . . . . . . . . 33
Output Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Period Rate /Continuous Rate Output Examples . . . . . . . . . . . . . . . . 36
Maximum Frequency. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Chapter 4
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Install the 1756-HSC Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Key the Removable
Terminal Block. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Wiring the Module. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Connect the Wires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Connect Ungrounded End of the Cable. . . . . . . . . . . . . . . . . . . . . 45
Publication 1756-UM007C-EN-P - November 2011
6 Table of Contents
Configure the 1756-HSC Module
Two Types of RTBs (each RTB comes with housing) . . . . . . . . . 46
Recommendations for Wiring Your RTB . . . . . . . . . . . . . . . . . . . 47
Wire Terminations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Wire an Allen-Bradley 845 Incremental Encoder . . . . . . . . . . . . . 47
Wire an Allen-Bradley Bulletin 872 3-Wire DC Proximity Sensor 48
Wire a PHOTOSWITCH Series 10,000 Photoelectric Sensor . . . 49
Assemble the Removable Terminal Block and Housing . . . . . . . . . . . 50
Install the Removable Terminal Block . . . . . . . . . . . . . . . . . . . . . . . . . 51
Remove the Removable Terminal Block . . . . . . . . . . . . . . . . . . . . . . . 52
Remove the Module
from the Chassis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Chapter 5
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
ControlLogix Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Direct Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Local Chassis Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Remote Chassis Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Use the Default Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Configure a 1756-HSC/B, Module by using
RSLogix 5000 Software, Version 18 and Later. . . . . . . . . . . . . . . . . . . 59
Communication Format Options. . . . . . . . . . . . . . . . . . . . . . . . . . 62
Set RPI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Set Up Counter Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Filter Selections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Set Up Output Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Copy Configuration (.C) Output, Rollover, Preset Tags to Output (.O)
Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Electronic Keying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Download Configuration
to the 1756-HSC Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Module Diagnostics
1756-HSC Status Indicators
1756-HSC Data Structures
Chapter 6
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
1756-HSC Error Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
RSLogix 5000 Diagnostics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Fault Type Determination. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Troubleshoot the 1756-HSC Module . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Appendix A
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Status Indicators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Appendix B
Configuration,Output,Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Publication 1756-UM007C-EN-P - November 2011
1756-HSC Module History
Application Considerations
Table of Contents 7
Configuration Structure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Output Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
Input Structure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
Appendix C
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
1756-HSC Profile Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
Configure a Generic Profile. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Copy ACD file . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Add Ladder Logic Routines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Upgrade Module to Software Version 18 and Later . . . . . . . . . . 101
Edit Thin Profile Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Change Configuration
Data via Message
Instruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Appendix D
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Types of Input Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Examples for Selecting Input Devices . . . . . . . . . . . . . . . . . . . . . . . . 106
Circuit Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Detailed Circuit Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
5V Differential Line Driver Example. . . . . . . . . . . . . . . . . . . . . . 108
+12 to +24V Single-ended Driver . . . . . . . . . . . . . . . . . . . . . . . . 109
Open Collector. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Electromechanical Limit Switch . . . . . . . . . . . . . . . . . . . . . . . . . . 111
Output Circuits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
Application Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
Input Cable Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
Totem-pole Output Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
Cable Impedance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
Cable Capacitance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
Cable Length and Frequency. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
Glossary
Index
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
Publication 1756-UM007C-EN-P - November 2011
8 Table of Contents
Publication 1756-UM007C-EN-P - November 2011
Preface
A
O
K
COUNTER
BZ
O
0
DC I/O
ABZ
00O111
01OO23
About This Publication
HSC Module Firmware 3.x Configurations
If you have
module
Using
firmware
revision
Series B
And your desired
functionality is
The 1756 High-speed Counter module counts incoming pulses from pulse
generators, counters, limit switches, and other devices, and can either return a
count to the controller or activate on-board outputs for a specific action
depending on your application. In the rest of this manual, we refer to the
High-speed Counter module as the 1756-HSC module.
The chapters in this manual focus on the configuration and operation of a
®
ControlLogix
1756-HSC/B module, firmware revision 3.x or later using
RSLogix™ 5000 software version 18 or later. Additional capabilities of the
1756-HSC module are highlighted in the appendices, including revised output
tags and electrical schematics.
The table outlines the profiles for the 1756-HSC/B module based on your
firmware and software configurations.
If you are using the ‘original’ 1756-HSC/A module, with either firmware
revision 1.x or 2.x, see
Then use the Logix5000™ profile Comment
Versions earlier than 15 => Thin profile/tags only Exact Match Keying
Original
(1)
Version 15…17 => Full profile support
Version 18 and later => Select Major Revision 3 and
HSC Data Comm Format
Appendix C
for details.
not supported
3.x
Rollover and Preset
in Output Tags
Versions earlier than 18 => Use generic profile/
HSC ACD file
(2)
Version 18 and later => Select Major Revision 3 and
Period/Continuous Rate
HSC Data-extended Comm Format
Totalizer
(1)
Original means the features and module behavior in the initial release of the 1756-HSC/A module, firmware revision 1.x functions and tags. See
(2)
File is located at
Who Should Use This Manual
http://samplecode.rockwellautomation.com.
You must be able to program and operate an Allen-Bradley® ControlLogix
controller and various Allen-Bradley encoders and sensors to efficiently use
your 1756-HSC module. In this manual, we assume that you know how to use
Appendix C
for details.
these products. If you do not, refer to the related user publications for each
product, before you attempt to use the 1756-HSC module.
9Publication 1756-UM007C-EN-P - November 2011 9
Preface
Additional Resources
These documents provide information related to the ControlLogix
High-speed Counter Module.
Resource Description
1756 ControlLogix I/O Technical Data,
publication 1756-TD002
ControlLogix System User Manual,
publication
ControlLogix Digital I/O Modules User
Manual, publication
ControlLogix Analog I/O Modules User
Manual, publication
1756-UM001
1756-UM058
1756-UM009
Provides specifications for the ControlLogix
controllers, I/O modules, specialty modules,
chassis, power supplies and accessories.
Detailed description of how to use your
ControlLogix operating system.
Detailed description of how to install and
use ControlLogix digital I/O Modules.
Detailed description of how to install and
use ControlLogix analog I/O Modules.
You can view or download publications at
http://www.rockwellautomation.com/literature
. To order paper copies of technical
documentation, contact your local Allen-Bradley distributor or Rockwell
Automation sales office.
10 Publication 1756-UM007C-EN-P - November 2011
1756-HSC Module Features
Chapter
1
Introduction
What is a High-speed Counter Module?
The High-speed Counter Module (catalog number 1756-HSC) performs
high-speed counting for industrial applications. This chapter provides an
overview of the design and features of the 1756-HSC/B module.
For other module series, firmware, and/or software information, see
Appendix C
Topic Page
What is a High-speed Counter Module? 11
Encoder and Sensor Compatibility 13
1756-HSC/B Module Features 13
The 1756-HSC module counts pulses by using a Counter or Frequency
operational mode. The counts are presented as either ‘accumulated count’ or
‘frequency’ depending on the mode that is configured for the module.
You can choose from either one of three Counter modes or one of three
Frequency modes when configuring the module. The operational mode
selected determines how the pulse count is stored and the behavior of the
outputs.
.
You can manipulate the storage of the count values (detailed in
1756-HSC module evaluates these count values against user configured presets
and/or values, thus the response time for activating outputs is performed at a
faster rate than evaluating in the controller.
Configuration tags, which are automatically installed with the 1756-HSC
module during the initial download in RSLogix 5000 programming software,
determine whether the module interprets pulses as:
• accumulated count - values can be 1…16 million.
• frequency - positive or negative depending on the direction of the
rotation.
Pulse count values can be calculated by using different types of Counter and
Frequency modes. The simple counter uses only input A to count pulses. An
encoder uses both input A and input B to count pulses. The relationship
between the two channels is how the encoder determines if the count is
positive (clockwise) or negative (counterclockwise).
11Rockwell Automation Publication 1756-UM007C-EN-P - November 2011
Chapter 2
). The
12 1756-HSC Module Features
This user manual also details the Frequency operational modes that are
available depending on which one is required for your application. Frequency
can be calculated in one of three ways:
• frequency (rate measurement).
•period rate.
• continuous rate.
All three Frequency modes determine the frequency of input pulses by
counting pulses over a user-defined time interval. If the revolution is spinning
in a clockwise direction, the frequency is positive; in a counterclockwise
direction it’s decreasing (negative) frequency.
See
page 29
Pulse counts and frequency values are stored in one of three input tags (based
on the mode) as shown in the table.
Mode and Input Tag Values for the 1756-HSC/B Module
for more details on Frequency modes.
Comm Format = HSC Data-extended Tags
Mode Mode Description Present Value Stored Value Totalizer
0 Counter
1 Encoder X1
Accumulated count Stored value
Directional frequency
2 Encoder X4
3 Counter Not Used N/A N/A N/A
4 Frequency
(Rate Measurement)
5 Frequency
(Period Rate)
6 Frequency
(Continuous Rate)
(1)
Modes where frequency controls the outputs.
(2)
B-input state defines direction (Counter mode).
(3)
Rollover/Preset settings apply.
(1)
(1)
See
No. of input pulses occurring
(1)
in sample period
No. of 4 MHz pulses
occurring in sample period
1756-HSC Data Structures
Accumulated count
Frequency
Accumulated count
in Appendix C for a list of tags.
(2)
(3)
Rockwell Automation Publication 1756-UM007C-EN-P - November 2011
1756-HSC Module Features 13
Encoder and Sensor Compatibility
1756-HSC/B Module
The most common applications using the 1756-HSC module also use the
following Allen-Bradley products:
• Allen-Bradley 845 incremental encoder
• Allen-Bradley Bulletin 872 three-wire DC proximity sensor
®
•PHOTOSWITCH
series 10,000 photoelectric sensor
Additional encoders and sensors may be connected to and used with the
ControlLogix 1756-HSC module. For specific compatibility of other encoder
and sensor compatibility, check the user publications for each product or
consult your local Allen-Bradley representative.
The table shows the type of encoder or sensor that you can choose for your
module.
Pulse Width, Min Frequency Range Leakage Current
Proximity 500 ns 1 MHz 250 A @ 5V DC
Quad Encoder 2 s 250 kHz 250 A @ 5V DC
This table highlights features of the 1756-HSC/B module.
Features
Feature Description
Real-time manipulation of preset/rollover
tag settings
Period rate / Continuous Rate frequencies Both Frequency modes are available with
Module-specific tags Tags are automatically created when you
Preset and Rollover tags, which provide a
reference point to start the count and reset
the count to zero, respectively, are included
in the Configuration tags at the initial
system configuration. The 1756-HSC/B
module also has both tags in the Output tag
settings to allow the values to be changed
in real-time when the 1756-HSC
Data-extended Comm Format is selected.
This feature provides the flexibility of
changing counter settings ‘on-the-fly’
without having to re-configure all system
tags.
the 1756-HSC/B module when using the
Data-extended Comm Format. Period Rate
mode counts internal 4 MHz clock pulses
over a used-defined time frame to
determine frequency. Continuous Rate
mode is similar to Period Rate mode except
dynamic outputs can be turned On /Off at
pre-determined pulse intervals.
add a 1756-HSC module to your Logix5000
project. The 1756-HSC module has very
descriptive tags for using pulse and
frequency values, such as Present Value,
Stored Value, and Totalizer.
Rockwell Automation Publication 1756-UM007C-EN-P - November 2011
14 1756-HSC Module Features
Additional I/O Module Features
The following items are additional features for ControlLogix I/O modules,
including the 1756-HSC module.
Feature Description
Configuration software RSLogix 5000 software has a custom interface to configure
your module. All module features can be enabled and
disabled through the software.
Module fault reporting I/O modules provide both hardware and software
indications when a module fault occurs. Status indicators
signal fault conditions. The RSLogix 5000 programming
software describes the fault message so you know what
action to take to resume normal operation.
Status indicators Status indicators on the front of the module report the
operational status of the 1756-HSC module. The input-point
status display indicates a particular point’s status, including
specifics for the input A, B, and Z (reset) points for each
channel of the 1756-HSC module. The output-point status
display indicates the status of four output points on the
1756-HSC module.
Producer/consumer model Logix5000 controllers let you produce (broadcast) and
consume (receive) system-shared tags. The 1756-HSC
module can produce data without having to be polled first by
a controller. The 1756-HSC module produces the data and
any owner-controller device can decide to consume it.
Electronic Keying See
RIUP RIUP is an abbreviation for removal and insertion under
page 73
in Chapter 5 for details.
power. The module can be inserted and removed from the
chassis while power is applied. This flexibility allows you to
maintain the module, either removing or inserting, without
disrupting the rest of the controlled process.
Rockwell Automation Publication 1756-UM007C-EN-P - November 2011
1756-HSC Parts Illustration
7
4
5
6
3
2
1
41623
1756-HSC Module Features 15
Item Description
1 Backplane connector - The backplane interface for the ControlLogix
system connects the module to the backplane.
2 Top and bottom guides - Guides provide assistance in seating the
removable terminal block (RTB) onto the module.
3 Connector pins - Input/output, power, and grounding connections are
made to the module through these pins with the use of an RTB.
4 Status indicators - Indicators display the status of communication, module
health, and presence of input/output devices. Use these indicators to help
in troubleshooting.
5 Locking tab - The locking tab anchors the RTB on the module, maintaining
6 Slots for keying - The slots let you mechanically key the RTB to prevent
wiring connections.
inadvertently making the wrong wire connections to your module.
7 Removable terminal block - The RTB lets you connect and house the
wiring. There are several types of RTBs.
See
page 46
for details on RTB types.
Rockwell Automation Publication 1756-UM007C-EN-P - November 2011
16 1756-HSC Module Features
Notes:
Rockwell Automation Publication 1756-UM007C-EN-P - November 2011
Counter Modes
Chapter
2
Introduction
This chapter describes the Counter modes for the 1756-HSC/B module.
Topics include:
• types of counting: counter and encoder.
• means of storing the counts.
• modes for manipulating the count.
• tags for control of on-board outputs.
Topic Page
Counter Mode 19
Encoder Mode 20
Preset 22
Rollover 22
Input Z (Gate/Reset) 23
Outputs 26
There are three Counter modes that can be selected from the Operational
Mode pull-down menu on the Counter Configuration tab.
See
Chapter 5
for configuration details.
Counter/Encoder Overview
The choices are:
• Counter mode (default).
• Encoder x1 mode.
• Encoder x4 mode.
The Encoder and Counter modes are virtually identical; the only difference is
the method used to count. There are two counters (using input A and B) per
module. Input Z, which is described in more detail later in this chapter,
basically affects how the counts are stored based on the selected Storage mode.
In Counter mode, the module reads incoming pulses from input A only and
stores the accumulated count value in the Present Value tag. The state of
input B determines whether to increment or decrement the count based on
whether it’s low, floating (count up) or high (count down).
In both Encoder modes, the 1756-HSC module uses two channels to read
incoming pulses. The module uses the phase relationship between
inputs A and B to determine the count value and direction of the rotation.
17Rockwell Automation Publication 1756-UM007C-EN-P - November 2011
18 Counter Modes
Where Count Values are Stored in Tags
Mode Description Present Value Tag Stored Value Tag Totalizer Tag
Counter
Encoder x4
• Encoder x1- This is a Bidirectional Count mode, counting up or down,
using an incremental encoder with direction output.
• Encoder x4 - This is a Bidirectional Count mode, using quadrature
encoder signals, with four times the resolution of X1.
The 1756-HSC/B module also offers the convenience of showing directional
frequency by using any Counter mode. If the count value is increasing, the
frequency is positive in the Totalizer tag. If the count value is decreasing, the
frequency is negative in the Totalizer tag.
Accumulated Count Stored Value Directional FrequencyEncoder x1
There are several methods for using and manipulating the count values. Based
on the state of the Z-input, the 1756-HSC module provides four modes of
behavior if the application requires storage of the accumulated count value.
Store and Continue Mode
•
•
Store, Wait, and Resume
•
Store and Reset, Wait, and Start
•
Store and Reset, and Start
In addition, the 1756-HSC module features two software-configurable tags
that provide control of the starting and ending points of an accumulated count
sequence. These are the tags:
Preset
•
•
Rollover
The remainder of this chapter details each mode and the different
configurations that you can use for specific needs of your
1756-HSC/B module.
Rockwell Automation Publication 1756-UM007C-EN-P - November 2011
Counter Modes 19
Single-phase Pulse Generator
Count Up Count Down
1756-HSC Module
Increment/Decrement Count
Input A
Input B
Input A
Input B
+
–
... 1 2 3 012
41688
Accumulated Count
in Present Value Tag
Positive Frequency
Negative Frequency
Directional Frequency
in Totalizer Tag
Input Z (optional)
Pulse Count
...
Counter Mode
This is the 1756-HSC module’s default operational mode that counts incoming
pulses using input A. You can control the starting and ending points of the
accumulated count depending on how you have configured the module.
In the Counter mode, the count increases or decreases based on the state of
input B, which can be a random signal. If input B is high, the counter will
count down. If input B is low or floating (that is, not connected to a voltage
source), the counter counts up. Counting is done on the leading-edge of
input A.
Input B Direction of Counter
High Down
Low or floating (not connected) Up
Input Z is used in Counter mode only if a Store Count mode is enabled.
page 23
See
for details on the Storage modes.
Counter Mode
Rockwell Automation Publication 1756-UM007C-EN-P - November 2011
20 Counter Modes
Encoder
Input A
Input B
Input A
Input B
B Leads A 90°
A Leads B 90°
Input A
Input B
123 210
1756-HSC Module
Change
Accumulated Count
in Present Value Tag
Directional Frequency
in Totalizer Tag
Positive Frequency Negative Frequency
44889
. . .
Input Z (optional)
Encoder Mode
Encoder mode also counts incoming pulses. However, the phase relationship
between two input channels (A and B) determines whether the direction of the
count is up or down.
In Encoder x1 mode, an increasing count results when channel B is 90° ahead
of channel A. The count is initiated on the rising edge of channel A, and the
direction of the encoder is clockwise (positive).
The module produces a decreasing count when channel A is 90° ahead of
channel B. The count is initiated on the falling edge of channel A, and the
direction is counterclockwise (negative).
By monitoring both the number of pulses and the phase relationships of
signals A and B, you can accurately determine the position and direction of the
rotation.
The illustration shows the phase relationships between channels A and B for
the x1 mode. Input Z is used in Encoder mode only if a Store Count mode is
page 23
enabled. See
for details on the Storage modes.
Encoder x1 Mode
Rockwell Automation Publication 1756-UM007C-EN-P - November 2011
Counter Modes 21
Input A
Quadrature Encoder
1756-HSC Module
Input B
Input A
Input B
Input A
Input B
B Leads A 90° A Leads B 90°
1 2 3 4 5 6 7 8 9 10 11 12 1234567891011 0
41689
Accumulated Count
in Present Value Tag
Directional Frequency
in Totalizer Tag
Positive Frequency Negative Frequency
Input Z (optional)
Encoder x4
Encoder x4 mode is identical to x1, except this mode counts on the leading
and trailing edges of A and B to provide a greater number of pulse counts. The
greater the number of pulse counts the better the module can
determine position.
Input Z is used in Encoder mode only if a Store Count mode is enabled.
page 23
See
Encoder x4 Mode
for details on the storage modes.
Maximum frequency in Encoder x1 and x4 modes = 250 kHz (assuming
50% duty cycle), with a minimum pulse width at this frequency of 2 s. The
Rockwell Automation Publication 1756-UM007C-EN-P - November 2011
module assumes a 90° phase (A/B°) difference between channels.
22 Counter Modes
Preset
Each of the two counters has one preset value associated with it. In the
Encoder or Counter modes, the preset value represents a reference point (or
value) from which the module begins counting. The module can count either
up or down from the preset value.
The preset value itself is entered during module configuration. However, you
must enter a preset command from either the RSLogix 5000 programming
software or ladder logic before it becomes active. Setting the Preset Enable Bit
in the Output tag to ‘1’ will send the preset value to the Present Value tag.
Preset values are entered on the Counter Configuration tab of the Module
Properties dialog box.
page 65
See
Preset in Output tag
When using the HSC Data-extended Comm Format while configuring the
module, the Preset tag will be found in both the Configuration and Output tag
areas.
for an example of the Counter Configuration tab.
The Configuration tag value is populated during software configuration with
the Logix5000 controller, and sent to the module upon powerup, defining its
behavior. This value will continue to define module behavior as long as the
corresponding tag in the output area is zero.
If the value of the Preset tag in the output area is changed to a non-zero value,
the module will disregard the value sent from the configuration area and use
the value in the output area instead. This facilitates easier real-time ‘on-the-fly’
changes to the preset function.
Rollover
Each of the two counters has one rollover value associated with it. When the
accumulated count value in the Rollover tag reaches the rollover value, it resets
to zero (0) and begins counting again. The rollover value is circular (for
example, if the rollover value = 360, the count will be from 358, 359, 0, 1, and
so forth, in a positive direction and from 1, 0, 359, 358, and so forth, in a
negative direction).
Rollover values are entered on the Counter Configuration tab of the Module
Properties dialog box in the RSLogix 5000 programming software or can be
changed in ladder logic.
page 65
See
Rockwell Automation Publication 1756-UM007C-EN-P - November 2011
for an example of the Counter Configuration tab.
Counter Modes 23
IMPORTANT
Rollover in Output tag
When using the HSC Data-extended Comm Format while configuring the
module, the Rollover tag will be found in both the Configuration and Output
tag areas.
The Configuration tag value is populated during software configuration with
the Logix5000 controller, and sent to the module upon powerup, defining its
behavior. This value will continue to define module behavior as long as the
corresponding tag in the Output area is zero.
If the value of the Rollover tag in the Output area is changed to a non-zero
value, the module will disregard the value sent from the Configuration area and
use the value in the Output area instead. This facilitates easier real-time
‘on-the-fly’ changes to the Rollover function.
Input Z (Gate/Reset)
Input Z, when active, will change the behavior of an accumulated count value
in the Present Value tag, depending upon which of four modes is selected.
Store and Continue Mode
•
•
Store, Wait, and Resume
•
Store and Reset, Wait, and Start
•
Store and Reset, and Start
The Storage modes are selected on the Counter Configuration tab on the
Module Properties dialog box of the RSLogix 5000 programming software.
Storage Modes
The store count feature allows the module to store the current count value and
follow four behavioral paths, depending on which Store mode is selected. The
store count is triggered by the state of the Z-input (the gate) on the module.
The four modes can be changed while normal module operation
continues. Improper use of on-the-fly changes may cause
unintended machine operation when the store count is used as
a trigger for machine sequencing.
The following illustrations show how the different modes store count values in
the Present Value and Stored Value tags.
Rockwell Automation Publication 1756-UM007C-EN-P - November 2011
24 Counter Modes
...10
Stored Value Tag
in Logix Controller
Present Value Tag
in Logix Controller
Z-Input
44900
11 12 13 14 15 16 17 18 19 20
...8 81313131313181818
Incoming Pulses
10 11 12 13 14 15 16 17 18 19 20
44901
Present Value Tag
in Logix Controller
Stored Value Tag
in Logix Controller
Z-Input
10
...1111
11 11
11 11
12 13 14 14 14 15 16
11 11 14 14 14 14 14
Incoming Pulses
10 11 12 13 14 15 16 17 18 19 20
Store and Continue Mode
In the Store and Continue mode, the module:
• reads the Present Value and places it into the Stored Value on the
leading edge of Input Z.
• continues to accumulate the Present Value based on presets and
incoming pulses.
• retains the Stored Value until it is overwritten by new data from the next
leading edge of a pulse on Input Z.
Store, Wait, and Resume
In the Store, Wait and Resume mode, the module:
• reads the Present Value and places it into the Stored Value on the
leading edge of Input Z.
• stops accumulating the count in the Present Value as long as the
Z-input is high.
• resumes accumulating the count in the Present Value when the
Z-input goes low.
• retains the Stored Value until it is overwritten by new data from the next
leading edge of a pulse on Input Z.
Rockwell Automation Publication 1756-UM007C-EN-P - November 2011
Counter Modes 25
Present Value Tag
in Logix Controller
Stored Value Tag
in Logix Controller
Z-Input
10 11 0 1 2 3 0 0 1 2
...11111111113 3 3 3 3
44902
Incoming Pulses
00 0
10 11 12 13 14 15 16 17 18 19 20
Present Value Tag
in Logix Controller
Stored Value Tag
in Logix Controller
Z-Input
10
...1111
01 2 3 4 0512
511 11 11 11 5 5 5 5
44903
34
10 11 12 13 14 15 16 17 18 19 20
Incoming Pulses
Store and Reset, Wait, and Start
In the Store and Reset, Wait, and Start mode, the module:
• reads the Present Value and places it into the Stored Value on the
leading edge of Input Z and resets the count to zero (0) in the Present
Value.
• resumes normal counting from zero (0) after the Z-Input goes low.
• retains the Stored Value until it is overwritten by new data from the next
leading edge of a pulse on Input Z.
Store and Reset, and Start
In the Store and Reset, and Start mode, the module:
• reads the Present Value and places it into the Stored Value on the
leading edge of Input Z and resets the count to zero (0) in Present
Value.
• resumes counting from zero (0) regardless of the state of the Z-input.
• retains the Stored Value until it is overwritten by new data from the next
leading edge of a pulse on Input Z.
Rockwell Automation Publication 1756-UM007C-EN-P - November 2011
26 Counter Modes
IMPORTANT
You have the option of selecting either the rising or falling edge
of the gate/reset pulse. When the Invert Z Value box is checked
on the Counter Configuration tab, the state of the Z input is
reversed as illustrated in the four Store modes.
For example, in the Store and Reset, and Start mode using the
Invert Z, the falling edge of the pulse on Input Z will store the
count value in the Stored Value tag and reset the Present Value
tag to zero. The counter continues to count while the gate pin is
low or high, but the present value is reset to zero (0) on the next
falling edge of Input Z.
Outputs
The module has four outputs, isolated in pairs (0 and 1, 2 and 3). Each output
is capable of sourcing current from an externally supplied voltage up to
30V DC. You must connect an external power supply to each of the output
pairs. The outputs can source 1 A DC and are hardware-driven. They turn On
or Off in less than 50 s when the appropriate count value has been reached.
Assign Outputs to Counters
By using configuration tags or the RSLogix 5000 software defaults, you can
assign the outputs on the module to any of the various counters. You can
assign as many as two outputs to a given counter. However, an output may be
assigned only once to a counter; it’s not possible to use the same output with
two different counters.
Each output on the 1756-HSC module can be turned On and Off at your
discretion. The operation of outputs tied to a counter (on the Output
Configuration tab of the Module Properties dialog box) are performed
independently from the controller scans.
Output Operation
When the outputs for the module are enabled and assigned to a counter, they
operate in an On-Off fashion. Up to two On-Off windows may be used for
each output. The outputs use a comparison of the Present Value to the values
you have programmed in one or both of the following tags:
• First Value Output Turns On and First Value Output Turns OFF
• Second Value Output Turns ON and Second Value Output Turns OFF
Rockwell Automation Publication 1756-UM007C-EN-P - November 2011
Counter Modes 27
2001…4999
5000
2000
10686
Accumulated Count
in Present Value Tag
For example, the ‘Output Turns ON’ tag is set for a value of 2000 and the
‘Output Turns OFF’ tag is set for a value of 5000.
In the illustration, the:
• output turns On at the Present Value of 2000.
• output remains energized for 3000 additional counts.
• output turns Off at the Present Value of 5000.
Tying Outputs to Counters
You can jumper any of the outputs to any of the counter inputs on the
module’s RTB. In this way, it is possible to use the outputs to reset a counter or
to cascade counters. If using the outputs this way, make certain that the correct
input terminals are used to interface with the appropriate output voltage.
Rockwell Automation Publication 1756-UM007C-EN-P - November 2011
28 Counter Modes
Notes:
Rockwell Automation Publication 1756-UM007C-EN-P - November 2011
Frequency Modes
Chapter
3
Introduction
This chapter describes the frequency modes that are available with the
1756-HSC/B module when using the HSC Data-extended
Comm Format.
The Frequency modes are:
• Frequency - number of input pulses per user-defined time interval.
• Period Rate - number of sampled, internal 4 MHz pulses per
user-defined number of incoming pulses, with outputs updated at the
end of the sample period with the Present Value, Totalizer, and
Stored Value tags.
• Continuous Rate - number of sampled, internal 4 MHz pulses per
user-defined number of incoming pulses, with outputs updated
throughout the sample period. The Present Value, Totalizer, and
Stored Value tags are updated only at the end of the sample period.
Topic Page
Frequency Mode 30
Period Rate and Continuous Rate Modes 32
Output Operation 35
Period Rate /Continuous Rate Output Examples 36
Frequency Overview
Each of the three Frequency modes use incoming pulse counts in a
user-defined interval to determine frequency values. The Stored Value tag
contains the calculated frequency and is always positive.
You can select one of three Frequency-operational modes based on the
frequency of the incoming signal. Frequency mode is best suited for
calculating higher frequencies because you define the sample period used to
count incoming pulses. At higher frequencies, there are a greater number of
pulses to be sampled that results in the ability to calculate frequency at a higher
resolution. The Stored Value tag is updated at the end of the selected sample
period.
Period Rate and Continuous Rate modes use an internal 4 MHz clock and a
user-defined number of incoming pulses configured by the Scaler value that
results in better performance at lower frequencies, where more 4 MHz pulses
are accumulated. Higher Scaler values also help to improve the calculation of
high frequency signals as longer pulse durations provide for more 4 MHz
pulses to be counted. Therefore, the combination of the Scaler and incoming
frequency determines the rate at which the frequency is updated in the
Stored Value tag.
29Rockwell Automation Publication 1756-UM007C-EN-P - November 2011
30 Frequency Modes
EXAMPLE
Where Frequency Values are Stored in Tags
Mode Description Present Value Tag Stored Value Tag Totalizer Tag
Frequency No. of input pulses occurring
Period Rate Frequency
Continuous Rate Frequency
The difference between the Period Rate and Continuous Rate modes is the
outputs are dynamic (On/Off) throughout the sample period for Continuous
Rate while Period Rate outputs are updated only at the end of the sample
period. Your desired output behavior should determine whether one uses
Period Rate or Continuous Rate modes.
page 35
See
in Sample Period
No. of 4 MHz pulses occurring
in Sample Period
for details.
Frequency Accumulated pulse count
Frequency Mode
In Frequency mode, the module counts incoming pulses on channel A for a
user-specified time interval that is configured in the Scaler tag. At the end of
the interval, the module returns a value representing the sampled number of
pulses in the Present Value tag, a value indicating the incoming frequency in
the Stored Value tag and a value indicating the total number of pulses that have
occurred in the Totalizer tag.
When the count and frequency are updated at the end of the sample period,
any associated outputs are checked against their associated presets. The output
On/Off values are related to the value in the Stored Value tag.
As you increase the Scaler (see
Sample Period for Frequency Mode
), the accuracy
of the frequency and the time between samples will increase. In general, if you
are measuring a higher frequency, the Scaler can be small. If you are measuring
a lower frequency, the Scaler likely will be larger.
Frequency = No. of pulses per sample period/Scaler Time.
For example, if the frequency = 30 Hz, and the Scaler = 100 ms, then
the Present Value tag returned = 3, and the Stored Value tag = 30.
Preset and rollover tag settings are active in this Frequency mode. User-defined
preset and rollover commands provide control of the starting and ending
points of incoming pulses, thus affecting the values in the Totalizer tag.
page 22
See
Rockwell Automation Publication 1756-UM007C-EN-P - November 2011
in Chapter 2 for preset and rollover tag details.
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