Rockwell international ALLEN-BRADLEY 1771-QRD User manual

1771-QRD Pulse Flowmeter Module
Installation and User’s Manual

1–1
copyright 1990 Allen-Bradley Company
Important
This module is designed for use ONLY as an operating control. Where an
operating control failure would result in personal injury and/or loss of
property, it is the responsibility of the system designer or end user to add
devices (safety, limit controls) or other systems (alarm, supervisory
systems) that protect against or warn of control failure.
Solid state equipment has operational characteristics differing from those
of electromechanical equipment. ‘Application Considerations for Solid
State Controls’ (publication SGI–1.1) describes some 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 is acceptable.
In no event will Allen-Bradley Company 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, Allen-Bradley Company cannot
assume responsibility or liability for actual use based on the examples and
diagrams.
No patent liability is assumed by Allen-Bradley Company with respect to
use of information, circuits, equipment or software described in this
manual.
Reproduction of the contents of this manual, in whole or part, without
written permission of the Allen-Bradley Company is prohibited.

Before You Begin 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Manual's Purpose 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Audience 1
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Vocabulary 1
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Overview
of the Manual 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Warnings and Cautions 2
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Explosion Hazard 2
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Related Products 2
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Product
Compatibility 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Related
Publications 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Introduction 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter Objectives 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Module Description and General Features 1
. . . . . . . . . . . . . . . . . .
How the 1771-QRD Works 2
. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
How the 1771-QRD Communicates With Programmable Controllers 3
Chapter Summary 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter Objective 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installing the 1771-QRD Module 1
. . . . . . . . . . . . . . . . . . . . . . . . .
Power Requirements 1
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Module
Location in the I/O Chassis 2. . . . . . . . . . . . . . . . . . . . . . .
Module Keying 2
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Wiring 2
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrostatic Discharge 3
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Module
Installation 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Indicators 7
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter Summary 7
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Module Programming 1. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter Objectives 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reading Data From The Module 1
. . . . . . . . . . . . . . . . . . . . . . . . .
Overrange and Overflow 2
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Block Transfer Programming 2
. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Example #1: PLC-5/15 Processor in a Local 1771 Backplane 3
. . . .
Example
#2: PLC-5/15 with Remote I/O 8. . . . . . . . . . . . . . . . . . . .
Example
#3: PLC-3/10 with Remote I/O 12. . . . . . . . . . . . . . . . . . . .
Table of Contents

Table of Contentsii
More on Overrange and Overflow 1. . . . . . . . . . . . . . . . . . .
Chapter Objectives 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Frequency Overrange Flags 1
. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Totalizer Overflow Flags 2
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Using A Block Transfer W
rite to Reset the T otalizer(s)
and/or Overflow Flags 3
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter Summary 5
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Troubleshooting 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter Objectives 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Data Formats 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Block Transfer Write Format From PLC to QRD 1. . . . . . . . . . . . . .
Response from QRD to PLC Block Transfer 1
. . . . . . . . . . . . . . . . .
Specifications 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Requirements 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Environment 1
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Agency Approval 1
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Packaging 1
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Weight 1
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Capacity 1
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Performance 1
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operational
Limits 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Chapter 1
1–1
Before You Begin
This manual shows you how to apply the 1771–QRD Pulse Flowmeter
Module to an Allen-Bradley PLC system. It describes methods for
installation, programming, and troubleshooting the module. It also
provides examples of how to use the module.
You must be able to program and operate an Allen-Bradley programmable
controller to make efficient use of this module. In particular, you must
know how to program Block Transfer instructions. If you do not, refer to
the appropriate programming and operations manual for the processor you
are using.
We refer to the:
Pulse Flowmeter Module (Catalog No. 1771–QRD) as “the module”, or
“the QRD”.
Programmable Controller as “the processor”.
This manual is divided into 6 chapters. The following table provides a brief
overview of the topics covered in each chapter.
Chapter Title Topics Covered
2 Introduction Description of module including
programmable features
3 Installation Module power requirements, keying chassis
location, field wiring
4 Programming Reading data from the module
Sample programs for various processors
5More on Overrange and Overflow Error codes
Block transfer write rung for resetting
totalizers and/or overflow flags
6 Troubleshooting Symptom/solution guide
Appendix A Data Formats Data formats fore Blcok Transfer Write and
Block Transfer Read
Appendix B Specifications
Manual's Purpose
Audience
Vocabulary
Overview of the Manual

Before You Begin
Chapter 1
1–2
Warnings are found in this manual and on the equipment. The following
symbols are used:
WARNING: A warning symbol means people might be injured
if the the procedures are not followed.
CAUTION: A caution symbol is used when machinery could
be damaged if the procedures are not followed. Explosion
Hazard
WARNING: Explosion hazard — substitution of components
may impair suitability for Class 1. Division 2
AVERTISSEMENT: Risque d’explosion — la substitution de
composants peut rendre ce matériel inacceptable pour les
emplacements de Classe 1, Division 2.
WARNING: Explosion hazard — do not disconnect equipment
unless power has been switched off or the area is known to be
non-hazardous.
AVERTISSEMENT: Risque d’explosion — avant de
déconnecter l’équipement, couper le courant ou s’assurer que
l’emplacement est designe non dangereux.
The 1771–QRD Module can be installed in any system that uses
Allen-Bradley PLC–2, PLC–3 or PLC–5 Programmable Controllers with
Block Transfer capability and 1771 I/O structure.
Contact your nearest Allen-Bradley office for more information about
programmable controllers.
Warnings and Cautions
Explosion Hazard
Related Products

Before You Begin
Chapter 1
1–3
Do not put the module Do not put the module in the same module group
as a discrete high-density module with 2 slot addressing.
Avoid placing the module adjacent to AC modules or high voltage DC
modules.
Consult the Allen-Bradley Industrial Computer Group Publications Index
(SD 499) for more information about programmable controllers.
Product Compatibility
Related Publications

Before You Begin
Chapter 1
1–4

Chapter 2
2–1
Introduction
In this chapter you will read about:
1771–QRD Pulse Flowmeter Module features
How the 1771–QRD Module communicates with programmable
controllers
The Catalog No. 1771–QRD Pulse Flowmeter Module is an intelligent
block transfer module that interfaces Programmable Controllers with
magnetic pickups, single channel shaft encoders, and turbine flowmeters,
or with any source of TTL pulses. The module is generally compatible
with, but does not require the use of, turbine flowmeter signal
preconditioning modules. It provides rate and count data in 2’s
complement binary format to the processor data table through block data
transfers.
Rates as high as 10.0 kHz and counts as large as 32,767 are supported. At
overflow, the count continues from zero and an overflow flag is set. The
overflow flag can be reset by the ladder logic. In addition, the PLC can
reset any or all counts directly.
The module functions with reduced performance in PLC–2 systems due to
their three digit BCD operation. Rates as high as 0.999 kHz are permitted
as are total counts of any size, provided that the PLC ladder polls the
module at intervals faster than it can acquire 999 counts.
The 1771–QRD module receives +5 Vdc operating voltage through the I/O
chassis backplane. It draws a maximum of 0.50 A from this supply.
The module is implemented in a 1771 single-density module form factor.
Chapter Objectives
Module Description and
General Features

Introduction
Chapter 2
2–2
Figure 2.1
A T ypical Channel
The QRD is operated with block transfers. Block Transfer Reads report the
count values, rates, and both overrange and overflow flags to the PLC.
Block Transfer Writes are used by the PLC to reset the total count or to
reset the overflow flags.
How the 1771-QRD W orks

Introduction
Chapter 2
2–3
The following is a step-by-step example of the information flow to and
from a 1771–QRD Module (Figure 2.2):
1. External devices (magnetic pickups, single channel encoders)
generate signals that are conducted to the 1771–QRD module.
2. The 1771–QRD module converts the incoming signals into counts
and rates, then stores these values until the PLC requests a transfer of
data.
3. When instructed by the ladder program, the processor performs a
Block Transfer Read of the values and stores them in the processor’s
data table.
4. In the case of a count overflow, the ladder program can sense the
overflow and reset the overflow flag, if desired, using data from
within a Block Transfer Write command. Any or all of the totalizers
can also be reset. (Note that when the totalizers are reset the overflow
flags are also reset.)
5. In the case of a rate overrange, the ladder program can sense the
overrange condition and act upon it accordingly.
6. The ladder program can use and/or move the data before it is written
over by the transfer of new data in a subsequent block transfer.
Figure 2.2
Information flow through a programmable controller/1771-QRD System
In this chapter you read about the functional aspects of the 1771–QRD
Module and how it communicates with a Programmable Controller.
How the 1771-QRD
Communicates With
Programmable Controllers
Chapter Summary

Chapter 3
3–1
Installation
In this chapter you will read how to install the 1771–QRD module in the
I/O chassis.
Read this installation section completely before installing the module.
Double check all connections before you begin programming.
WARNING: Disconnect and lock out all power from the
controller and system power supplies before installing and
wiring modules to avoid injury to personnel and damage to
equipment.
Before installing the 1771–QRD Module in the I/O chassis:
1. Calculate the power requirements of all the modules in the chassis.
See the section below titled “Power Requirements”.
2. Determine the location of the module in the I/O chassis. See the
section titled “Module Location in the I/O chassis”.
3. Key the backplane connectors in the I/O chassis. See the sect ion
titled “Module Keying”.
4. Connect the field wiring. See the section titled “Wiring”.
The1771–QRD Module receives its power through the 1771 I/O chassis
backplane from the chassis power supply. It does not require any other
external power supply to function. When planning the system, consider the
power usage of all modules in the I/O chassis to prevent overloading the
chassis backplane or power supply. Each 1771–QRD Module requires 0.50
A at +5VDC. Add this to the requirements of all other modules in the I/O
chassis.
CAUTION: Do not insert or remove modules from the I/O
chassis while system power is on. Failure to observe this rule
may result in damage to the module circuitry.
Chapter Objective
Installing the 1771-QRD
Module
Power Requirements

Installation
Chapter 3
3–2
Place the module in any I/O module slot of the I/O chassis except for the
extreme left slot. This slot is reserved for the programmable controllers or
adapter modules. In addition:
1. Do not put the module in the same module group as a discrete
high-density module with 2-slot addressing. However, other
single-slot modules may be placed in the same module group.
2. Do not put the module adjacent to AC or high voltage DC I/O
modules, to minimize electrical noise and temperature effects. Noise
can be minimized by grouping input and output modules together
within an I/O chassis.
See the user’s manual of any other intelligent I/O modules involved for
possible grouping limitations.
Module Keying Plastic keying bands, shipped with each I/O chassis
provide an easy method for keying I/O slots to accept only one type of
module. The module is slotted in two places on the edge of the rear circuit
board. The position of the keying bands on the backplane connector must
correspond to these slots to allow insertion of the module. You can key any
connector in an I/O chassis to receive this module except for the leftmost
connector reserved for processor or adapter modules. Place the keying
band between the following numbers labeled on the backplane connector:
between pins 2 and 4
between pins 6 and 8
You may change the positions of the bands if subsequent system design
and rewiring makes insertion of a different type of module necessary. Use
needle-nose pliers to insert or remove a keying band.
WARNING: To avoid injury to personnel and damage to
equipment, disconnect and lock out power from the processor
and system power supplies before wiring the m module.
Connections to/from I/O devices are made to the field wiring arm (catalog
no. 1771–WG shipped with the module. Attach the wiring arm to the pivot
bar at the bottom of the I/O chassis. It pivots upward and connects with the
module so you can install or remove the module without disconnecting the
wires.
Module Location in the I/O
Chassis
Module Keying
Wiring

Installation
Chapter 3
3–3
The sensor cable must be shielded. The shield must extend the length of
the cable, but be connected only at the 1771–QRD end. The recommended
sensor wiring cable type is Belden 8761 or similar. The functions of the
individual terminals of the field wiring arm are shown in Figure 3.1.
The wiring diagrams for both magnetic pickups and TTL are shown in
Figures 3.2 and 3.3, respectively.
Electrostatic Discharge Electrostatic discharge can damage the integrated
circuits in this module, if you touch the backplane connector pins. Avoid
electrostatic damage by observing the following precautions:
Touch a grounded object to rid yourself of charge before handling the
module.
Do not touch the backplane connector or connector pins.
When not in use, keep module in its static-shield bag.
CAUTION: Electrostatic discharge can degrade performance
or damage the module. Handle as stated above.
Now that you have determined the power requirements, location, keying
and wiring for the 1771–QRD Module, you are ready to install it in the I/O
chassis.
1. Turn off power to the chassis.
2. Place the module in the plastic tracks on the top and bottom of the
slot to guide the module into position.
3. Seat the module into the connector by applying firm, even pressure.
Do not force the module into its backplane connector.
4. Snap the chassis latch over the top of the module to secure its
position.
5. Connect the wiring arm to the module.
6. Turn on power to the chassis. The green “ACTIVE” light should be
illuminated. If it is not lit, there is no power being applied to the
module. Turn the power off, re-insert the module and try again.
Connect one or more signal sources to the 1771–QRD. The signal source
can be a magnetic pickup/turbine flowmeter or TTL pulses.
Electrostatic Discharge
Module Installation

Installation
Chapter 3
3–4
Figure 3.1
Field W iring Arm
WARNING: Explosion hazard. Do not disconnect equipment
unless power has been switched off or the area is known to be
nonhazardous.
AVERTISSEMENT: Risque d’explosion. Avant de
déconnecter l’équipment, couper le courant ou s’assurer que
l’emplacement est designe non dangereux.

Installation
Chapter 3
3–5
Figure 3.2
W iring for Pickups or Flowmeters

Installation
Chapter 3
3–6
Figure 3.3
W iring for Active TTL Drivers
Note: The jumper between terminals 17 and 19 changes the sensitivity of
channels 3 and 4 so that they are compatible with TTL pulses.
The jumper between terminals 17 and 20 changes the sensitivity of
channels 1 and 2 so that they are compatible with TTL pulses.
Signal types may not be mixed within a channel pair.
For use with magnetic pickups or turbine flowmeters, do not connect a
jumper to these terminals.
WARNING: Remove power from the 1771 I/O chassis
backplane and from the wiring arm before removing or
installing the module.
Failure to remove power from the backplane or the wiring arm could
cause module damage, degradation of performance or injury.
Failure to remove power from the backplane could cause injury or
equipment damage due to possible unexpected operation.

Installation
Chapter 3
3–7
There are three indicator LEDs on the front panel. The indicator LED
functions are listed in Table 3.A.
Table 3.A
Indicators
Legend Color Type Function
FAULT Red Solid One or more inputs are above 10.0 kHZ
FAULT Red Flashing Internal hardware failure, or input rates drifiting above
and below 10.0 kHz
PROG Yellow Flashing Block transfer in process
ACTIVE Green Solid Module active
In this chapter you read how to install the 1771–QRD Module in a
Programmable Controller system, as well as how to wire the field wiring
arm.
Indicators
Chapter
Summary

Chapter 4
4–1
Module Programming
In this chapter you will learn about:
Reading data from the 1771–QRD module
Writing data to the 1771–QRD module
Black transfer programming format
Programming techniques
Block Transfer Read programming moves 9 words from the 1771–QRD
Module to the processor’s data table. The ladder program initiates the
request to transfer data from the QRD to the processor.
Figure 4.1 illustrates the module’s response after the PLC processor’s
block transfer request for counts and rates.
Figure 4.1
Module' s Response to Block T ransfer Read Request
Word 0 1 0 0 0
Word 1 Channel 1 Rate
Word 2 Channel 1 Total
Word 3 Channel 2 Rate
Word 4 Channel 2 Total
Word 5 Channel 3 Rate
Word 6 Channel 3 Total
Word 7 Channel 4 Rate
Word 8 Channel 4 Total
Chapter Objectives
Reading Data From The
Module

Module Programming
Chapter 4
4–2
Word 0 (1000) is the header code that identifies the data source as a
1771–QRD module. When the module is active, it also contains the status
of the overrange and overflow flags. Overrange and overflow are discussed
in more detail in the next section of this chapter. Word #1 contains the rate
of the signal on channel 1; word #2 contains the total number of pulses
received on channel 1. Word #3 contains the rate of the signal on channel
2; word #4 contains the total number of pulses received on channel 2.
Word #5 contains the rate of the signal on channel 3; word #6 contains the
total number of pulses received on channel 3. And finally, words #7 and #8
contain the rate and total number of pulses received on channel 4,
respectively.
The 1771–QRD processes input signals at a maximum rate of 10.0kHz. If
the rate of the incoming signal on any channel is greater than 10.0 kHz, the
red FAULT indicator will illuminate, revealing an overrange. At the same
time, a bit will be set in the acknowledge word (word 0), showing the
channel(s) whose rate is in an overrange condition. The red FAULT light
will extinguish only when the frequency of the input that is causing the
overrange is reduced to less than 10.0 kHz. At that time, the FAULT light
will go out, and the overrange flag for that channel will automatically be
reset. Overrange rates are reported as zero values, and cause their totalizers
to reset to zero.
The 1771–QRD also acts as a totalizer for each of the channels. Each of
the totalizers is capable of counting up to 32,767. When this number is
reached by any of the totalizers, an overflow flag for that channel is set in
the acknowledge word. The counter will again start from zero and continue
to count, with the overflow flag set. These flags can be detected by the
processor, and any or all of them can be reset using a Block Transfer Write
command. Examples of the detection and handling of overflow conditions
with a BTW command are discussed further in Chapter 5.
The following sections show how to program and set up typical
programmable controllers for use with the 1771–QRD Module. In each
example, the switch settings for all of the processors and adapters used are
given, as well as the backplane settings for the I/O chassis. Note that 2-slot
addressing is used in all of these examples, but the 1771–QRD will
function with any type of addressing (2-slot, 1-slot, 1/2-slot).
Overrange and Overflow
Block Transfer Programming