1. Please read all the information in this owner’s guide before installing
the product.
2. The information in this owner's guide applies to hardware series B and
firmware version 2.0 or later.
3. This guide assumes that the reader has a full working knowledge of the
relevant processor.
Notice
The products and services described in this owner's guide are useful in a
wide variety of applications. Therefore, the user and others responsible
for applying the products and services described herein are responsible
for determining their acceptability for each application. While efforts
have been made to provide accurate information within this owner's
guide, Spectrum Controls assumes no responsibility for the accuracy,
completeness, or usefulness of the information herein.
Under no circumstances will Spectrum Controls be responsible or liable
for any damages or losses, including indirect or consequential damages
or losses, arising out of either the use of any information within this
owner's guide or the use of any product or service referenced herein.
No patent liability is assumed by Spectrum Controls with respect to the
use of any of the information, products, circuits, programming, or
services referenced herein.
The information in this owner's guide is subject to change without notice.
Limited Warranty
Spectrum Controls warrants that its products are free from defects in
material and workmanship under normal use and service, as described in
Spectrum Controls literature covering this product, for a period of 1 year.
The obligations of Spectrum Controls under this warranty are limited to
replacing or repairing, at its option, at its factory or facility, any product
which shall, in the applicable period after shipment, be returned to the
Spectrum Controls facility, transportation charges prepaid, and which
after examination is determined, to the satisfaction of Spectrum Controls,
to be thus defective.
This warranty shall not apply to any such equipment which shall have
been repaired or altered except by Spectrum Controls or which shall
have been subject to misuse, neglect, or accident. In no case shall the
liability of Spectrum Controls exceed the purchase price. The
aforementioned provisions do not extend the original warranty period of
any product which has either been repaired or replaced by Spectrum
Controls.
Who Should Use
This Guide
Preface
Read this preface to familiarize yourself with the rest of the owner’s
guide. This preface covers:
• who should use this guide
• what this guide covers
• related Allen-Bradley documents
• terms & abbreviations you should know
Use this guide if you design, install, program, or maintain a control system
that uses Allen-Bradley Small Logic Controllers.
You should have a basic understanding of SLC 500 products. You should
also understand electronic process control and the ladder program
instructions required to generate the electronic signals that control your
application. If you do not, contact your local Allen-Bradley representative
for the proper training before using these products.
What This Guide
Covers
Related AllenBradley Documents
This guide covers the 1746sc-NI8u universal analog input module. It
contains the information you need to install, wire, use, and maintain these
modules. It also provides diagnostic and troubleshooting help should the
need arise.
Table A lists several Allen-Bradley documents that may help you as you
use these products.
iiSLC 500™ Universal Analog Input Modules
Table A. Related Allen-Bradley documents
Allen-Bradley Doc. No.Title
1747-2.30SLC 500 System Overview
SGI-1.1Application Considerations for Solid State Controls
1770-4.1Allen-Bradley Programmable Controller Grounding and
1747-6.2Installation & Operation Manual for Modular Hardware
1747-NI001Installation & Operation Manual for Fixed Hardware Style
To obtain a copy of any of the Allen-Bradley documents listed, contact
your local Allen-Bradley office or distributor.
You should understand the following terms and abbreviations before using
this guide.
A/D - Refers to analog-to-digital conversion. The conversion produces a
digital value whose magnitude is proportional to the instantaneous
magnitude of an analog input signal.
Attenuation – The reduction in magnitude of a signal as it passes through
a system. The opposite of gain.
Channel – Refers to one of eight, small-signal analog input interfaces to
the module’s terminal block. Each channel is configured for connection to
a thermocouple or DC millivolt (mV) input device, and has its own
configuration and status words.
Chassis – See rack.
Prefaceiii
CJC - (Cold Junction Compensation) The means by which the module
compensates for the offset voltage error introduced by the temperature at
the junction between the thermocouple lead wire and the input terminal
block (the cold junction).
Common mode rejection ratio (CMRR) - The ratio of a device’s
differential voltage gain to common mode voltage gain. Expressed in dB,
CMRR is a comparative measure of a device’s ability to reject
interference caused by a voltage common to its terminal relative to
ground.
Common mode voltage – The voltage difference between the negative
terminal and analog common during normal differential operation.
Configuration word – Contains the channel configuration information
needed by the module to configure and operate each channel. Information
is written to the configuration word through the logic supplied in your
ladder program.
Cut-off frequency - The frequency at which the input signal is attenuated
3 dB by the digital filter. Frequency components of the input signal that
are below the cut-off frequency are passed with under 3 dB of attenuation
for low-pass filters.
dB (decibel) – A logarithmic measure of the ratio of two signal levels.
Data word – A 16-bit integer that represents the value of the analog input
channel. The channel data word is valid only when the channel is enabled
and there are no channel errors.
Digital filter - A low-pass filter of the A/D converter. The digital filter
provides high-frequency noise rejection.
Effective resolution – The number of bits in the channel data word that
do not vary due to noise.
Full-scale error (gain error) – The difference in slope between the
actual and ideal analog transfer functions.
Full-scale range (FSR) – The difference between the maximum and
minimum specified analog values.
Gain drift – The change in full-scale transition voltage measured over the
operating temperature range of the module.
Input data scaling - Depends on the data format that you select for the
channel data work. You can select from scaled-for-PID or Engineering
Units for millivolt, milliamp, thermocouple, RTD, or CJC inputs, which you
must compute to fit your application’s temperature or voltage resolution.
ivSLC 500™ Universal Analog Input Modules
Local System - A control system with I/O chassis within several feet of
the processor, and using 1746-C7 or 1746-C9 ribbon cable for
communication.
LSB (least significant bit) – The bit that represents the smallest value
within a string of bits. The “weight” of this value is defined as the fullscale range divided by the resolution.
Mulitplexer – A switching system that allows several input signals to
share a common A/D converter.
Normal mode rejection (differential mode rejection) – A logarithmic
measure, in dB, of a device’s ability to reject noise signals between or
among circuit signal conductors, but not between the equipment grounding
conductor or signal reference structure and the signal conductors.
Module update time – See channel update time.
Remote system - A control system shere the chassis can be located
several thousand feet from the processor chassis. Chassis communication
is via the 1747-SN Scanner and 1747-ASB Remote I/O Adapter.
Resolution – The smallest detectable change in a measurement, typically
expressed in engineering units (e.g. 0.15 °C) or as a number of bits. For
example, a 12-bit system has 4096 possible output states. It can therefore
measure 1 part in 4096. See also effective resolution.
RTD (Resistance Temperature Detector) - A temperature sensing
element with 2, 3, 4, lead wires. It uses the basic characteristics that
electrical resistance of metals increases with temperature. When a small
current is applied to the RTD, it creates a voltage that varies with
temperature. This voltage is processed and converted by the RTD module
into a temperature value.
Sampling time - The time required by the A/D converter to sample an
input channel.
Status word – Contains status information about the channel’s current
configuration and operational state. You can use this information in your
ladder program to determine whether the channel data word is valid.
Step response time – The time required for the A/D signal to reach
95% of its expected, final value, given a full-scale step change in the
output data word.
Update time – The time for the module to sample and convert a channel
input signal and make the resulting value available to the SLC processor.
Table of Contents
Preface
Who Should Use This Guide .................................................................................. i
What This Guide Covers ......................................................................................... i
Related Allen-Bradley Documents ......................................................................... i
Table A. Related Allen-Bradley documents.......................................................... ii
Terms & Abbreviations You Should Know ............................................................ ii
Module Overview
Installing And Wiring
Your Module
Chapter 1
General Description................................................................................................ 1
System Overview .................................................................................................... 3
Compatibility with RTD and Resistance devices and cables............................. 6
Table 4.5Channel 0-7 Status Word (I:e.0 through I:e.7) -
Bit Definitions ...................................................................................46
Table 6.1Module-status LED .......................................................................... 6 4
Table 6.2Module-status and Channel-status LED ....................................... 6 4
Chapter 1
Module Overview
This chapter describes the universal analog input module and explains how
the SLC controller reads thermocouple or millivolt analog input data from
the module. Read this chapter to familiarize yourself further with your
universal analog input module. This chapter covers:
• general description and hardware features
• an overview of system and module operation
• block diagram of channel input circuits
General Description
This module is designed exclusively to mount into Allen-Bradley 1746 I/
O racks for use with Allen-Bradley SLC 500 fixed and modular systems.
The module stores digitally converted thermocouple, RTD, millivolt (mV),
volt (V), milliamp (mA), and CJC temperature analog data in its image
table for retrieval by all fixed and modular SLC 500 processors. The
module supports connections of up to eight channels of thermocouple,
current or voltage inputs, OR four channels of RTD or resistance inputs
and four channels of thermocouple, current or voltage inputs.
Input Ranges
The following tables provide compatibility information on the supported
thermocouple types and their associated temperature ranges, the
supported RTD types and their associated temperature ranges, as well as
the millivolt, volt, milliamp and resistance input types supported by the
NI8u module. To determine the practical temperature range of your
thermocouple, refer to the specifications in appendices A and B. Detailed
accuracy specifications for all input types can be found in appendix A.
Table 1.1Thermocouple Temperature Ranges
Type°C Temperature Range°F Temperature Range
J-210°C to 760°C-346°F to 1400°F
K-270°C to 1370°C-454°F to 2498°F
T-270°C to 400°C-454°F to 752°F
B300°C to 1820°C572°F to 3308°F
E-270°C to 1000°C-454°F to 1832°F
R0°C to 1768°C32°F to 3214°F
S0°C to 1768°C32°F to 3214°F
N0°C to 1300°C32°F to 2372°F
C0°C to 2315°C32°F to 4199°F
CJC Sensor-25°C to 105°C-13°F to 221°F
2SLC 500™ Universal Analog Input Module
Table 1.2 RTD Temperature Ranges
Type°C Temperature Range°F Temperature Range
Platinum (385)1100 Ohm-200°C to +850°C-328°F to +1562°F
Platinum (3916)1100 Ohm-200°C to +630°C-328°F to +1166°F
Copper (426)10 Ohm-100°C to +260°C-148°F to +500°F
Nickel (618)120 Ohm-100°C to + 260°C-148°F to +500°F
Nickel (672)120 Ohm-80°C to +260°C-112°F to + 500°F
200 Ohm-200°C to +750°C-328°F to +1382°F
500 Ohm-200°C to +850°C-328°F to +1562°F
1000 Ohm-200°C to +850°C-328°F to +1562°F
200 Ohm-200°C to +630°C-328°F to +1166°F
500 Ohm-200°C to +630°C-328°F to +1166°F
1000 Ohm-200°C to +630°C-328°F to +1166°F
1=The digits following the RTD type represent the temperature coefficient of resistance
(alpha, a), which is defined as the resistance change per Ohm per
Platinum 385 refers to a platinum RTD with a = 0.00385 Ohms/Ohm - °°C, or simply
0.00385/°°C.
°
°
C. For instance,
Table 1.3 Millivolt Input Ranges
-50 to +50 mV
-100 to +100 mV
-500 to +500 mV
-2.0 to +2.0 V
0 to +5.0 V
1.0 to +5.0 V
0 to 10.0 V
-10.0 to +10.0 V
Table 1.4 Current Input Ranges
4 to 20 mA
0 to 20 mA
Table 1.5 Resistance Input Range
0 to 3000 Ohms
Chapter 1: Module Overview3
All eight input channels are individually configurable for thermocouple,
millivolt, volt, or milliamp input types. Channels 4 through 7 can be defined
for RTD or resistance inputs, and then can be individually configured for a
specific RTD or resistance type. Each input channel provides broken
input, over-range, and under-range detection and indication, when enabled.
Hardware Features
The module fits into any single slot for I/O modules in either an SLC 500
modular system or an SLC 500 fixed system expansion chassis (1746-A2).
1
It is a Class 1
1
Requires use of Block Transfer in a remote configuration.
module (uses 8 input words and 8 output words).
The module utilizes two removable terminal blocks, that provides
connections for the eight input channels. There are two cold-junction
compensation (CJC) sensors that compensate for the cold junction at
ambient temperature rather than at freezing (0°C). There are four current
sources for supplying the RTD or resistance sensors. The module is
configured through software, with jumpers used to define RTD,
resistance, current or voltage input paths.
System Overview
Table 1.6 Hardware Features
HardwareFunction
Channel Status LED IndicatorsDisplay operating and fault status of channels 0-7
Module Status LEDDisplays operating and fault status of the module
Side Label (Nameplate)Provides module information
Removable Terminal BlockProvides electrical connection to input devices
Door LabelPermits easy terminal identification
Self Locking TabsSecure module in chassis slot
Diagnostic LEDs
The module contains diagnostic LEDs that help you identify the source of
problems that may occur during power-up or during normal operation.
Power-up and channel diagnostics are explained in Chapter 6, TestingYour Module.
The module communicates with the SLC 500 processor and receives
+5 Vdc and +24 Vdc power from the system power supply through
the parallel backplane interface. No external power supply is
required. You may install as many universal modules in the system
as the power supply can support.
4SLC 500™ Universal Analog Input Module
The first four input channels (0 through 3) can receive input signals from
thermocouples, millivolt, volt, or milliamp devices. The last four input
channels (4 through 7) can receive input signals from thermocouples,
millivolt, volt, milliamp, or 2, 3 or 4-wire RTD or resistance devices. If
RTD or resistance inputs are selected, channels 4 through 7 can be
individually configured for the supported RTD or resistance types.
When configured for thermocouple input types, the module converts
analog input voltages into cold-junction compensated and linearized, digital
temperature readings. The module uses the National Institute of
Standards and Technology (NIST) linearization tables based on ITS-90 for
thermocouple linearization.
When configured for RTD input types, the module converts the analog
input voltages into digital temperature readings, based on the alpha type,
wire type, and ohms specified. The standards used are the JIS C 16041997 for the Pt 385 RTD types, the JIS C 1604-1989 for the Pt 3916 RTD
types, SAMA RC21-4-1966 for the 10Ω Cu 426 RTD, DIN 43760 Sept.
1987 for the 120Ω Ni 618 RTD, and MINCO Application Aid #18 May
1990 for the 120Ω Ni 672 RTD.
When configured for millivolt, volt, milliamp, or resistance analog inputs,
the module converts the analog values directly into digital counts. For
those input types, the module assumes that the input signal is linear prior to
input into the module.
System Operation
At power-up, the module checks its internal circuits, memory, and basic
functions. During this time the module status LED remains off. If the
module finds no faults, it turns on its module status LED.
After completing power-up checks, the module waits for valid channel
configuration data from your SLC ladder logic program (channel status
LEDs are off). After channel configuration data is transferred and
channel enable bits are set for one or more channels, the module turns on
its channel status LEDs. Then it continuously converts the inputs to the
data format you selected for the channel.
Each time the module reads an input channel, the module tests that data
for a fault, i.e. over-range, or under-range condition. If open-circuit
detection is enabled, the module tests for an open circuit condition. If it
detects an open-circuit, over-range, or under-range condition, the module
sets a unique bit in the channel status word and causes the channel status
LED to blink.
The SLC processor reads the converted thermocouple, RTD,
resistance, millivolt, volt, or milliamp data from the module at the
end of the program scan, or when commanded by the ladder
program. After the processor and module determine that the data
transfer was made without error, the data can be used in your ladder
program.
Chapter 1: Module Overview5
Module Operation
The module’s input circuitry consists of eight differential analog inputs,
multiplexed into an A/D converter. The A/D converter reads the analog
input signals and converts them to digital counts. The input circuitry also
continuously samples the CJC sensors and compensates for temperature
changes at the cold junction (terminal block). The module can be used
with remote CJC sensor inputs. The sensors must be Analog Devices
AD592CN temperature transducers. The module will not accept other
CJC sensor inputs, and thermocouple inputs will not function properly if
incorrect CJC sensors are used.
Module Addressing
The module requires eight words each in the SLC processor’s input and
output image tables. Addresses for the module in slot e are as follows:
I:e.0-7thermocouple/mV/V/mA, RTD, resistance or status
data for channels 0-7, respectively
O:e.0-7 configuration data for channels 0-7, respectively.
Compatibility with Thermocouple, Current, and
Millivolt Devices & Cables
The module is compatible with the following standard types of
thermocouples: B, E, J, K, N, R, S, T and C and extension wire.
Refer to appendices B and C for details. The module is also
compatible with a variety of voltage and current devices with an
output of ±50, ±100 mV, +500mV, ±2V, 0-5V, 1-5V, 0-10V, ±10V,
0-20mA, and 4-20mA.
To minimize interference from radiated electrical noise, we
recommend twisted-pair and highly shielded cables such as the
following:
Table 1.7 Recommendations to minimize
interference from radiated electrical noise
For This Type of DeviceWe Recommend This Cable (or equivalent)
Thermocouple Type JEIL Corp. J20-5-502
Thermocouple Type KEIL Corp. K20-5-510
Thermocouple Type TEIL Corp. T20-5-502
Other Thermocouple Typesconsult with EIL Corp or other manufacturers
mV, V, mA devicesBelden 8761, shielded, twisted-pair
6SLC 500™ Universal Analog Input Module
Compatibility with RTD and Resistance devices and
cables
and 3 possible wire types (2 wire, 3 wire, or 4 wire). Each RTD input
individually supports four input pins on the terminal block: one excitation
current source (EXC+), one excitation current drain (EXC-), one sense
positive (CH+) and one sense negative (CH-). Only those pins are
connected that are required by the selected RTD or resistance wire type.
For 2, 3, or 4 wire configurations, the module can support a maximum
combined cable length associated with an overall cable impedance of 25
ohms or less without exceeding its input limitations. The accuracy
specifications provided herein do not include errors associated with
unbalanced cable impedance.
Since the operating principle of the RTD and resistance inputs is based on
the measurement of resistance, take special care in selecting your input
cable. For 2-wire or 3-wire configuration, select a cable that has a
consistent impedance throughout its entire length. For 2-wire
configurations, we recommend that you use Belden #9501 (or
equivalent). For 3-wire configurations, we recommend that you use
Belden #9533 (or equivalent) for short installation runs (less than 100
feet) or use Belden #83503 (or equivalent) for longer runs (greater
than 100 feet) and in high humidity environments.
Table 1.8 Cable Specifications
DescriptionBelden #9501Belden#9533Belden#83503
For 2-wire RTDs andFor 3-wire RTDs andFor 3-wire RTDs and
When used?potentiometers.potentiometers. Shortpotentiometers. Long
runs less than 100 feetruns greater than 100
and normal humidityfeet or high humidity
levels.levels.
AgencyNEC Type CMNEC Type CMNEC Art-800, Type CMP
Approval
Temperature80°C80°C200°C
Rating
Chapter 1: Module Overview7
Block Diagram
DC Voltage +
Analog Input -
Thermocouple
Input
0-20 mA +
Current Input -
RTD or
resistance
Input
RTD
Sense +
Sense
Return
CJCA +
Sensor -
CH2 +
CH2 -
SHIELD 2/3
CH 3 +
CH 3 -
EXC 6 +
CH6 +
CH6 -
EXC 6 -
Shield 6/7
EXC 7 +
CH 7 +
CH 7 -
EXC 7 -
CH 0 +
CH 0 -
SHIELD 0/1
CH 1+
CH 1 -
EXC 4 +
CH 4 +
CH 4 -
EXC 4 -
SHIELD 4/5
EXC 5 +
CH 5 +
CH 5 -
EXC 5 -
CJCB +
Sensor -
Vcc
Vcc
Vcc
Vcc
Multiplexers
Analog
to Digital
Converter
Digital
Filter
User Selected
Filter Frequency
Digital
Value
8SLC 500™ Universal Analog Input Module
Electrostatic
Damage
Chapter 2
Installing And Wiring Your Module
Read this chapter to install and wire your module. This chapter
covers:
• avoiding electrostatic damage
• determining power requirements
• installing the module
• wiring signal cables to the module’s terminal block
Electrostatic discharge can damage semiconductor devices inside this
module if you touch backplane connector pins. Guard against
electrostatic damage by observing the following precautions:
Power Requirements
CAUTION
!
The module receives its power through the SLC-500 chassis backplane
from the fixed or modular +5 VDC and +24 VDC chassis power supply.
The maximum current drawn by the module is shown in the table below.
ELECTROSTATICALLY SENSITIVE COMPONENTS
• Before handling the module, touch a grounded
object to rid yourself of electrostatic charge.
• When handling the module, wear an approved
wrist strap grounding device.
• Handle the module from the front, away from the
backplane connector. Do not touch backplane
connector pins.
• Keep the module in its static-shield container
when not in use or during shipment.
Failure to observe these precautions can degrade the module’s
performance or cause permanent damage.
10SLC 500™ Universal Analog Input Module
Table 2.1.Maximum current drawn by the
module
5VDC Amps24VDC Amps
0.120 0.100
When using the module in a modular system, add the values shown
above to the requirements of all other modules in the SLC to prevent
overloading the chassis power supply.
When using the module in a fixed controller, be sure not to exceed
the power supply rating for the 2-slot I/O chassis.
Considerations for a Modular System
Place your module in any slot of an SLC-500 modular, or modular
expansion chassis, except for the left-most slot (slot 0) reserved for
the SLC processor or adapter modules.
ShuntShunt
Shunt
ShuntShunt
ConfigurationConfiguration
Configuration
ConfigurationConfiguration
Considerations for a Fixed Controller
The power supply in the 2-slot SLC 500 fixed I/O chassis (1746-A2)
can support only specific combinations of modules. Make sure the
chassis power supply can support the NI8u and additional module
power requirements.
The 1746sc-NI8u module is a multi-purpose, multi-functional
module, that is capable of supporting many different input types in a
very small package. There are a few shunts on the board that allow
the user to define input paths properly, which are imperative for the
configuration control to allow proper utilization of the module. JP1
through JP8 supports the current input mode options of each of the
inputs channels, 0 through 7, respectively. In order to define
channels 4 through 7, JP9 and JP10, must be configured properly.
JP11 is used at the factory and should not be modified. JP12
indicates whether or not RTD or resistance inputs are to be used in
the configuration. The module is shipped with all current input
shunts in place, and the remaining shunts installed for non-RTD or
resistance inputs. The shunts are to be modified prior to installation
of the module. Proper precautions for electrostatic handling should
be followed. Small needlenose pliers may be used to configure the
shunts, if needed.
AA
TTENTION:TTENTION:
A
TTENTION: Never touch the module without
AA
!
TTENTION:TTENTION:
being properly strapped and connected to ground.
Electrostatic damage may result.
Chapter 2: Installing And Wiring Your Module11
JP11
The following diagram shows the module outline defining the placement of
the various shunts, looking at the primary side of the board, with the
terminal block pointing up. A brief description of each follows.
Terminal Block Header
JP1 JP2 JP3 JP4 JP5 JP6 JP7 JP8
JP9
JP10
JP11
JP12
JP1, JP2, JP3, JP4,
JP5, JP6, JP7, and
JP8 Setup
Current Input
Non-Current Input
JP11 Setup
There are eight shunts corresponding to eight inputs, respectively,
that exist to support the 0 to 20mA or 4 to 20mA current input
selections. JP1 corresponds to channel 0, and JP8 corresponds to
channel 7. The shunts of JP2 through JP7 follow for channels 1
through 6, respectively. These shunts are two pin headers that only
need to be connected if a channel is to be configured for current
input. If the channel is to be used for any other type (thermocouple,
millivolt, voltage for channels 0 through 3, or thermocouple,
millivolt, voltage, RTD, or resistance for channels 4 through 7), then
the pins are to be left open and unconnected.
Shunt in place
Shunt removed
Located in the bottom right hand corner, JP11 should always have
pins 1 and 2 connected as shown. This shunt is used during
manufacturing of the module, and should never be moved by the
user.
12SLC 500™ Universal Analog Input Module
JP9, JP10, and JP12
Setup
The NI8u module supports up to four RTD or resistance inputs on
channels 4 through 7. In order to properly support RTD or resistance
inputs, JP9, JP10, and JP12 have to be configured correctly. The
function of JP9 and JP10 is to define the input path for the channels 4
through 7. JP9 and JP10 are four pin headers toward the right side of
the board, looking at the primary side of the board with the terminal
block pointing up. JP12 is a three pin header on the very bottom
right hand corner, below JP11.
Setting For RTD or
Resistance Inputs
The module will either support zero RTD or resistance inputs or four
RTD or resistance inputs in channels 4 through 7. To properly
configure JP9 and JP10 for RTD or resistance, set the shunts across
pins 2 and 3 of the four pin headers. JP12 also needs to have pins 2
and 3 connected when RTD or resistance are to be used, as shown
below.
Setting For Non-RTD
or Resistance Inputs
JP9
JP10
JP12
If RTD and resistance inputs are not used, and channels 4 through 7
are to be defined as thermocouple inputs, current inputs, millivolt or
voltage inputs, jumper pins 1 and 2 together, jumper pins 3 and 4
together, of JP9 and JP10, as defined below. JP12 also needs to have
pins 1 and 2 connected when RTD and resistance inputs are not in
use.
JP9
JP10
JP12
Selecting A Rack
Slot
Chapter 2: Installing And Wiring Your Module13
Two factors determine where you should install your module in the
rack: ambient temperature and electrical noise. When selecting a slot
for your module, try to position your module:
• in a rack close to the bottom of the enclosure (where the air is
cooler)
• away from modules that generate significant heat, such as 32-point
input/output modules
• in a slot away from ac or high-voltage dc modules, hard contact
switches, relays, and ac motor drives
• away from the rack power supply (if using a modular system)
Remember that in a modular system, the processor always occupies
the first slot of the rack.
Module Installation
and Removal
When installing the module in a chassis, it is not necessary to remove
the terminal blocks from the module. However, if the terminal blocks
are removed, use the write-on label located on the side of the terminal
blocks to identify the module location and type.
1746sc-
RACK_______SLOT_______
NI8u
1746sc-
RACK_______SLOT_______
NI8u
CAUTION
!
POSSIBLE EQUIPMENT OPERATION
Before installing or removing your module, always
disconnect power from the SLC 500 system and from
any other source to the module (in other words, don’t
“hot swap” your module), and disconnect any devices
wired to the module.
Failure to observe this precaution can cause unintended
equipment operation and damage.
TB1
TB2
14SLC 500™ Universal Analog Input Module
TB2
TB1
To insert your module into the rack, follow these steps:
1. Align the circuit board of your module with the card guides at the top
and bottom of the chassis.
Figure 2.1.Module insertion into a rack
2. Slide your module into the chassis until both top and bottom retaining
clips are secure. Apply firm even pressure on your module to attach it
to its backplane connector. Never force your module into the slot.
Cover all unused slots with the Card Slot Filler, Allen-Bradley part number
1746-N2.
Terminal Block Removal
To remove the terminal block:
Using a screwdriver or needle-nose pliers, carefully unscrew and
then pry the terminal block loose. When removing or installing the
terminal block be careful not to damage the CJC sensors.
Chapter 2: Installing And Wiring Your Module15
Figure 2.2.Terminal block diagram with CJC
sensors
CJC Sensors
CH0+
CH0Shield 0/1
CH1+
CH1-
EXC4+
CH4+
CH4-
EXC4-
Shield 4/5
EXC5+
CH5+
CH5-
EXC5-
CJCB+
CJCB-
CJC Sensors
CAUTION
TB1
TB2
CJCA+
CJCACH2+
CH2-
SHIELD 2/3
CH3+
CH3-
EXC6+
CH6+
CH6EXC6SHIELD 6/7
EXC7+
CH7+
CH7EXC7-
LEDS
Wiring Your Module
POSSIBLE EQUIPMENT OPERATION
!
Before wiring your module, always disconnect power
from the SLC 500 system and from any other source to
the module.
Failure to observe this precaution can cause unintended
equipment operation and damage.
Follow these guidelines to wire your input signal cables:
• Power, input, and output (I/O) wiring must be in accordance with
Class 1, Division 2 wiring methods [Article 501-4(b) of the
National Electrical Code, NFPA 70] and in accordance with the
authority having jurisdiction.
• Peripheral equipment must be suitable for the location in which it
is used.
• Route the field wiring away from any other wiring and as far as
possible from sources of electrical noise, such as motors,
16SLC 500™ Universal Analog Input Module
transformers, contactors, and ac devices. As a general rule, allow at
least 6 in. (about 15.2 cm) of separation for every 120 V of power.
• Routing the field wiring in a grounded conduit can reduce electrical
noise further.
• If the field wiring must cross ac or power cables, ensure that they cross
at right angles.
• To limit the pickup of electrical noise, keep thermocouple, RTD,
millivolt, and milliamp signal wires as far from power and load
lines as possible.
• For improved immunity to electrical noise, use Belden 8761
(shielded, twisted pair) or equivalent wire for millivolt sensors; or
use shielded, twisted pair thermocouple extension lead wire
specified by the thermocouple or RTD manufacturer. Using the
incorrect type of thermocouple extension wire or not following the
correct polarity may cause invalid readings.
Wiring RTD or
Resistance Sensors
to the NI8u Module
• There is one shield pin for every two input channels. All shields
are internally connected, so any shield terminal can be used with
any channel.
• Ground the shield drain wire at only one end of the cable. The
preferred location is at the shield connections on the terminal
block. (Refer to IEEE Std. 518, Section 6.4.2.7 or contact your
sensor manufacturer for additional details.)
• Keep all unshielded wires as short as possible.
• To limit overall cable impedance, keep input cables as short as
possible. Locate your I/O chassis as near the RTD or
thermocouple sensors as your application will permit.
• Tighten screw terminals with care. Excessive tightening can strip
a screw.
• Follow system grounding and wiring guidelines found in your
SLC 500 Installation and Operation Manual.
The NI8u module supports two, three, and four wire RTDs or
resistance inputs connected individually to the module (channels 4
through 7), as shown in the figure below.
ADD
JUMPER
EXC4+
CH4+
CH4EXC4-
Shield 4/5
Chapter 2: Installing And Wiring Your Module17
2-Wire RTD Interconnection
RTD
RETURN
CABLE SHIELD
3-Wire RTD Interconnection
ADD
JUMPER
EXC4+
CH4+
CH4-
EXC4-
Shield 4/5
EXC4+
CH4+
CH4-
EXC4-
Shield 4/5
RTD
SENSE
RETURN
CABLE SHIELD
4-Wire RTD Interconnection
RTD
SENSE POS
SENSE NEG
RETURN
CABLE SHIELD
These are:
* 2-wire RTDs, which are composed of 2 RTD lead wires (RTD and
Return)
* 3-wire RTDs, which are composed of a Sense and 2 RTD lead wires
(RTD and Return)
* 4-wire RTDs, which are composed of 2 Sense and 2 RTD lead wires
(RTD and Return).
In any RTD sensing system, it is important that the lead and sense wire
resistances are matched as much as possible. The lead lengths, and their
resulting impedances, must be matched and kept small to eliminate the
introduction of connectivity errors. The 4-wire RTDs are the most
accurate, with 2-wire RTDs being the most inaccurate. In 2-wire the lead
resistance adds error to the resulting degree reading. With a 200µA
current source, 1Ω of lead resistance adds 200µV, or 3.45°C error, with
the 100Ω 385 alpha type. To gain an understanding of how lead
resistance affects RTD readings, the µV/C for each RTD type is listed
below. The current source is 200µA.
The accuracies specified for the NI8u RTDs do not include errors due to
lead resistance imbalances.
Important: To ensure temperature or resistance value accuracy, the
resistance difference of the cable lead wires must be equal to or less
than 0.01 ohms.
There are several ways to insure that the lead values match as closely as
possible. They are as follows:
Preparing and
Wiring the Cables
* Keep total lead resistance as small as possible, and less than 25 ohms.
* Use quality cable that has a small tolerance impedance rating.
* Use a heavy gauge lead wire which has less resistance per foot.
To prepare and connect cable leads and drain wires, follow these
steps:
Signal Wires
Cable
Drain Wire
(At the module-end of the cable, extract
the drain wire but remove the foil shield.)
(Remove foil shield and drain wire
from sensor-end of cable.)
Signal Wires
1. At each end of the cable, strip some casing to expose individual
wires.
2. Trim signal wires to 5-inch lengths beyond the cable casing. Strip
about 3/16 inch (4.76 mm) of insulation to expose the ends of the
wires.
3. At the module-end of the cables (see figure above):
Chapter 2: Installing And Wiring Your Module19
- extract the drain wire and signal wires
- remove the foil shield
- bundle the input cables with a cable strap
4. Connect pairs of drain wires together, Channels 0 and 1, Channels 2
and 3, Channels 4 and 5, Channels 6 and 7. Keep drain wires as short
as possible.
5. Connect the drain wires to the shield inputs of the terminal block.
Channel 0 and 1 drain wires to the shield 0/1 input pin
Channel 2 and 3 drain wires to the shield 2/3 input pin
Channel 4 and 5 drain wires to the shield 4/5 input pin
Channel 6 and 7 drain wires to the shield 6/7 input pin
6. Connect the signal wires of each channel to the terminal block.
Important: Only after verifying that your connections are correct
for each channel, trim the lengths to keep them short. Avoid
cutting leads too short.
7. Connect the chassis ground terminal/lug to the nearest chassis
mounting bolt with 14 gauge wire. (Looking at the face of the
module, the terminal/lug is near the terminal block and above
power supply PS2 on the primary side of the PCB.)
8. At the source-end of cables from mV devices:
- remove the drain wire and foil shield
- apply shrink wrap as an option
- connect to mV devices keeping the leads short
Important: If noise persists, try grounding the opposite end of the
cable, instead (Ground one end only.)
Important: For CE compliance, Ferrite EMI Suppressors are needed
on each channel’s terminal block connection. If remote CJCs are
installed, shielded wire must be used and a Ferrite EMI suppressor is
needed on each CJC input connection. The drain wire of the CJC
cable must be connected to a shield connection at the module. Apply
the suppressor close to the module terminal block, as shown below.
A Steward Part 28B2024-0A0 or equivalent is recommended. The
Steward 28B2024-0A0 has an impedance of 157Ω at 25 MHz, 256Ω at
100 MHz, and can accomodate one turn of wire.
20SLC 500™ Universal Analog Input Module
Figure 2.3Ferrite EMI suppressor for CE
Note: Please refer to Appendix C for additional information on
wiring and using grounded junction, ungrounded junction and
exposed juction thermocouple types.
Figure 2.4Terminal block diagram with input
compliance
Module
cable
THERMOCOUPLE, mA,
mV or V CABLE
4-WIRE RTD CABLE
3-WIRE RTD CABLE
THERMOCOUPLE, mA,
mV or V CABLE
TB1
CH0+
CH0-
Shield for CH0 and CH1
CH1+
CH1-
EXC4+
CH4+
CH4-
EXC4-
Shield for CH4 and CH5
EXC5+
CH5+
CH5-
EXC5-
CJCB+
CJCB-
TB2
CJC A+
CJC A -
CH2+
CH2-
Shield for CH2 and CH3
CH3+
CH3-
EXC6+
CH6+
CH6-
EXC6-
Shield for CH6 and CH7
EXC7+
CH7+
CH7-
EXC7-
Chapter 2: Installing And Wiring Your Module21
The module also has a ground terminal TB1 which should be grounded to
a chassis mounting bolt with 14 gauge wire.
Cold Junction Compensation (CJC)
CAUTION
!
To obtain accurate readings from each of the channels, the cold
junction temperature (temperature at the module’s terminal junction
between the thermocouple wire and the input channel) must be
compensated for. Two cold junction compensating sensors have
been integrated in the removable terminal block. They must remain
installed to retain accuracy. If remote CJC compensation is desired,
the sensors at the terminal block must be removed and the external
sensors wired to the CJCA and CJCB terminals. The remote CJC
sensors must be Analog Devices AD592CN T0-92 style temperature
transducer devices. The module will not function with any other
CJC sensor connected.
POSSIBLE EQUIPMENT OPERATION
Do not remove or loosen the cold junction
compensating temperature transducers located on the
terminal block unless you are connecting remote CJCs
to the module. Both CJCs are critical to ensure
accurate thermocouple input readings at each channel.
The module will not operate in thermocouple mode if a
CJC is not connected.
Failure to observe this precaution can cause unintended
equipment operation and damage.
22SLC 500™ Universal Analog Input Module
Chapter 3
Things To Consider Before Using
Your Module
This chapter explains how the module and the SLC processor
communicate through the processor’s I/O image tables. It also
describes the module’s input filter characteristics. Topics discussed
include:
• module ID code
• module addressing
• channel filter frequency selection
• Channel turn-on, turn-off, and reconfiguration times
• response to slot disabling
Module ID Code
Module Addressing
The module ID code is a unique number assigned to each type of
1746 I/O module. The ID defines for the processor the type of I/O
module and the number of words used in the processor’s I/O image
table.
With APS software, use the system I/O configuration display to
manually enter the module ID when assigning the slot number during
the configuration. Do this by selecting (other) from the list of
modules on the system I/O configuration display and enter 3500, the
ID code for the 1746sc-NI8u.
No special I/O configuration (SPIO CONFIG) is required. The
module ID automatically assigns the correct number of input and
output words.
If you are using different programming software package, refer to the
documentation that came with your software.
The following memory map shows you how the SLC processor’s
output and input tables are defined for the module.
24SLC 500™ Universal Analog Input Module
Figure 3.1Image table
SLC 5/0X
Data Files
Slot e
Output Image
Slot e
Input Image
Output
Scan
Input
Scan
Bit 15Bit 0Address
Thermocouple
Module
Image Table
Output Image
8 Words
Input Image
8 Words
Bit 15Bit 0Address
Channel 0 Configuration Word
Channel 1 Configuration Word
Channel 2 Configuration Word
Channel 3 Configuration Word
Channel 4 Configuration Word
Channel 5 Configuration Word
Channel 6 Configuration Word
Channel 7 Configuration Word
Channel 0 Data or Status Word
Channel 1 Data or Status Word
Channel 2 Data or Status Word
Channel 3 Data or Status Word
Channel 4 Data or Status Word
Channel 5 Data or Status Word
Channel 6 Data or Status Word
Channel 7 Data or Status Word
Word 0O:e.0
Word 1O:e.1
Word 2O:e.2
Word 3O:e.3
Word 4O:e.4
Word 5O:e.5
Word 6O:e.6
Word 7O:e.7
Word 0I:e.0
Word 1I:e.1
Word 2I:e.2
Word 3I:e.3
Word 4I:e.4
Word 5I:e.5
Word 6I:e.6
Word 7I:e.7
Output Image - Configuration Words
Eight words of the SLC processor’s output image table are reserved
for the module. Output image words 0-7 are used to configure the
module’s input channels 0-7. Each output image word configures a
single channel, and can be referred to as a configuration word. Each
word has a unique address based on the slot number assigned to the
module.
Example Address - If you want to configure channel 2 on the
module located in slot 4 in the SLC chassis, your address would be
O:4.2.
File type
Element
Delimiter
Slot
Word
O:4.2
Word
Delimiter
Chapter 4, Channel Configuration, Data, and Status, gives you
detailed bit information about the data content of the configuration
word.
Chapter 3: Things To Consider Before Using Your Module25
Input Image - Data Words and Status Words
Eight words of the SLC processor’s input image table are reserved
for the module. Input image words are multiplexed since each
channel has one data word and one status word. The corresponding
configuration word selects whether the channel status or channel data
is in the input image word.
Status bits for a particular channel reflect the configuration settings
that you entered into the configuration (output image) word for that
channel. To receive valid status, the channel must be enabled and the
module must have stored a valid configuration word for that channel.
Each input image word has a unique address based on the slot
number assigned to the module.
Example Address - To obtain the status/data word of channel 2
(input word 2) of the module located in slot 4 in the SLC chassis use
address I:4:2.
Channel Filter
Frequency Selection
File type
Element
Delimiter
Slot
Word
I:4.2
Word
Delimiter
Chapter 4, Channel Configuration, Data, and Status, gives you
detailed bit information about the content of the data word and the
status word.
The universal module uses a digital filter that provides high
frequency noise rejection for the input signals. The digital filter is
programmable, allowing you to select from four filter frequencies for
each channel. The digital filter provides the highest noise rejection at
the selected filter frequency. The graphs to follow show the input
channel frequency response for each filter frequency selection.
Selecting a low value (i.e. 10 Hz) for the channel filter frequency
provides the best noise rejection for a channel, but it also increases
the channel update time. Selecting a high value for the channel filter
frequency provides lower noise rejection, but decreases the channel
update time.
The following table shows the available filter frequencies, cut-off
frequency, step response, and ADC effective resolution for each filter
frequency.
26SLC 500™ Universal Analog Input Module
Table 3.1 Cut-off frequency, step response time, and
The step response is calculated by a 3 x (1/filter frequency) settling time.
Channel Cut-Off Frequency
The channel filter frequency selection determines a channel’s cut-off
frequency, also called the -3 dB frequency. The cut-off frequency is
defined as the point on the input channel frequency response curve
where frequency components of the input signal are passed with 3
dB of attenuation. All frequency components at or below the cut-off
frequency are passed by the digital filter with less than 3 dB of
attenuation. All frequency components above the cut-off frequency
are increasingly attenuated, as shown in the graphs below.
The cut-off frequency for each input channel is defined by its filter
frequency selection. The table above shows the input channel cut-off
frequency for each filter frequency. Choose a filter frequency so that
your fastest changing signal is below that of the filter’s cut-off
frequency. The cut-off frequency should not be confused with
update time. The cut-off frequency relates how the digital filter
attenuates frequency components of the input signal. The update
time defines the rate at which an input channel is scanned and its
channel data word updated.
Chapter 3: Things To Consider Before Using Your Module27
Figure 3.2 Signal attenuation with 10 Hz input filter
-3 dB
Amplitude (in dB)
0
-20
-40
-60
-80
-100
-120
-140
-160
-180
-200
0102030405060 Hz
Signal Frequency
2.62 Hz
Figure 3.3 Signal attenuation with 50 Hz input filter
-3 dB
Amplitude (in dB)
0
-20
-40
-60
-80
-100
-120
-140
-160
-180
-200
050100150200250300 Hz
13.1 Hz
Signal Frequency
28SLC 500™ Universal Analog Input Module
Figure 3.4 Signal attenuation with 60 Hz input filter
-3 dB
Amplitude (in dB)
0
-20
-40
-60
-80
-100
-120
-140
-160
-180
-200
060120180240300360 Hz
Signal Frequency
15.7 Hz
Figure 3.5 Signal attenuation with 250 Hz input filter
-3 dB
Amplitude (in dB)
0
-20
-40
-60
-80
-100
-120
-140
-160
-180
-200
0250500750100012501500 Hz
Signal Frequency
65.5 Hz
Channel Step Response
The channel filter frequency determines the channel’s step response.
The step response is time required for the analog input signal to reach
95% of its expected, final value given a full-scale step change in the
input signal. This means that if an input signal changes faster than
the channel step response, a portion of that signal will be attenuated
by the channel filter. Table 6 shows the step response for each filter
frequency.
Chapter 3: Things To Consider Before Using Your Module29
Update Time
Channel 0 Disabled
Enabled
Sample
Channel 0
Update CJC
The universal module update time is defined as the time required for the
module to sample and convert the input signals of all enabled input
channels and make the resulting data values available to the SLC
processor. It can be calculated by adding the sum of all enabled sample
times, plus one CJC update time or one lead resistance update time.
Channel 1 DisabledChannel 2 Disabled
Enabled
Sample
Channel 1
Calculate
Previous
Enabled
The following table shows the channel sampling time for each filter
frequency.
Table 3.2 Channel Sampling Time
Channel Sampling Time for Each Filter Frequency (all values ±1 msec)
250 Hz Filter60 Hz Filter50 Hz Filter10 Hz Filter
Channel 7 Disabled
Sample
Channel 2
Calculate
Previous
Channel Sampling Time
Enabled
Channel 7
Sample
Calculate
Previous
Sample CJC or
Lead Resistance
Calculate
Previous
26 msec64 msec74 msec314 msec
The times above include a settling time necessary between input channel
readings.
In addition, on each module scan the module will sample either one CJC
input or one lead resistance input if any enabled channel input type is a
thermocouple, RTD, or resistance input. The CJC sampling time is 64
msec. The lead resistance sampling time is equal to the channel sampling
time for that RTD. When both thermocouple inputs and RTD or
resistance inputs are used, the module will alternate between sampling one
CJC and one lead resistance.
The fastest module update time occurs when only one millivolt channel
with a 250 Hz filter frequency is enabled.
Module update time = 26 msec
The slowest module update time occurs when eight channels, four
thermocouples and four RTDs, each using a 10 Hz filter frequency,
are enabled.
Channel Turn-On,
Turn-Off, and
Reconfiguration
Times
Auto-Calibration
Module update time= 274 msec
The time required for the module to recognize a new configuration
for a channel is generally one module update time plus 1.865 msec
per newly configured channel. If the filter frequency selected for the
newly enabled, configured channel is new to the module, then autocalibration will be performed following configuration recognition.
Turn-off time requires up to one module update time.
Reconfiguration time is the same as turn-on time.
Auto-calibration is performed by the module to correct for drift errors
over temperature. Auto-calibration occurs immediately following
configuration of a previously unselected filter frequency for the
particular input path. If all enabled channels have the calibration
disable configuration bit set to zero, auto-calibration also occurs as a
continuous cycle, where every two minutes all the required filter
frequencies and input paths are calibrated. There are three input paths in
the system to accommodate all the input options: a low voltage input path,
Chapter 3: Things To Consider Before Using Your Module31
a mid voltage input path, and a high voltage input path. The following table
correlates input type to input path.
Each input path supports four different filter frequencies: 10Hz,
50Hz, 60Hz and 250Hz. The following table indicates autocalibration time based on the input path, and the selected filter
frequency.
CJC sensors are acquired through the low voltage input path at
60Hz, to maximize the trade-offs between resolution and update rate.
Once every two minutes, the module calibrates one of the input path and
filter combinations on successive scans until all input path and filter
combinations that are used have been calibrated. During auto-calibration,
the module scan time will increase by the auto-calibration time.
Auto-calibration can be disabled by placing a one in any enabled channel’s
auto-cal disable bit.
32SLC 500™ Universal Analog Input Module
Response to Slot
Disabling
By writing to the status file in the modular SLC processor, you can disable
any chassis slot. Refer to your SLC programming manual for the slot
disable/enable procedure.
CAUTION
!
Input Response
When a universal slot is disabled, the universal module continues to
update its input image table. However, the SLC processor does not
read input from a module that is disabled. Therefore, when the
processor disables the universal module slot, the module inputs
appearing in the processor image table remain in their last state, and
the module’s updated image table is not read. When the processor reenables the module slot, the current state of the module inputs are
read by the processor during the subsequent scan.
Output response
The SLC processor may change the universal module output data
(configuration) as it appears in the processor output image.
However, this data is not transferred to the universal module. The
outputs are held in their last state. When the slot is re-enabled, the
data in the processor image is transferred to the universal module.
POSSIBLE EQUIPMENT OPERATION
Always understand the implications of disabling a
module before using the slot disable feature.
Failure to observe this precaution can cause unintended
equipment operation.
Channel
Configuration
Chapter 4: Channel Configuration, Data, and Status33
Chapter 4
Channel Configuration, Data,
and Status
Read this chapter to:
• configure each input channel
• check each input channel’s configuration and status
Channel configuration words appear in the SLC controller’s output image
table as shown below. Words 0-7 correspond to module channels 0-7.
After module installation, you must configure each channel to establish the
way the channel operates (e.g., input type, temperature units, etc.). You
configure the channel by setting bits in the configuration word using your
programmer. We present bit descriptions next.
SLC Output Image (Configuration) Words
15
O:e.0
O:e.2
O:e.3
O:e.4
O:e.5
O:e.6
O:e.7
e = slot number of the module
0
Channel 0 Configuration Word
Channel 1 Configuration WordO:e.1
Channel 2 Configuration Word
Channel 3 Configuration Word
Channel 4 Configuration Word
Channel 5 Configuration Word
Channel 6 Configuration Word
Channel 7 Configuration Word
34SLC 500™ Universal Analog Input Module
The configuration word default settings are all zero. Next, we describe
how you set configuration bits of a channel configuration word to set up
the following channel parameters:
• type of thermocouple , RTD, resistance, mV, V, or mA input
• RTD or resistance type of 2-wire, 3-wire or 4-wire
• data format such as engineering units, counts, or scaled for PID
• how the channel should respond to a detected open input circuit, if
applicable
• filter frequency selection
• temperature units in °C or °F
• whether the channel is enabled or disabled
• whether auto-calibration is enabled or disabled
Channel
Configuration
Procedure
• whether status or data information is selected for the module’s input
image table.
The channel configuration word consists of bit fields, the settings of which
determine how the channel will operate. This procedure looks at each bit
field separately and helps you configure a channel for operation. Refer to
the chart on the following page and the bit field descriptions that follow for
complete configuration information.
1. Determine which channels are used in your program and enable them.
Place a one in bit 0 if the channel is to be enabled. Place a zero in bit 0
if the channel is to be disabled.
2. Determine the input device type (thermocouple, RTD, resistance, mV,
V, or mA) for a channel and enter its respective 5-digit binary code in
bit field 1-5 of the channel configuration word. Remember that only
channels 4-7 support the RTD and resistance options. Make sure that
the shunts are set accordingly for the input types specified.
3. Select a data format for the data word value. Your selection
determines how the analog input value from the A/D converter will be
expressed in the data word. Enter your 2-digit binary code in bit field 67 of the channel configuration word. Not all data formats apply to all
Chapter 4: Channel Configuration, Data, and Status35
input types. Check table 11 to make sure you selected a valid
combination.
4. Determine the desired state for the channel data word if an open circuit
condition is enabled and detected for that channel. Enter the 2-digit
binary code in bit field 8-9 of the channel configuration word. Not all
input types support open circuit detection. Review the “Open Circuit
State” description on page 43 to verify applicability.
5. If the channel is configured for thermocouple inputs, RTD or the CJC
sensor, determine if you want the channel data word to read in degrees
Fahrenheit or degrees Celsius and enter a one or a zero in bit 10 of the
configuration word. If the channel is configured for a mV, V, mA, or
resistance analog sensor, enter a zero in bit 9.
6. Determine the desired input filter frequency for the channel and enter
the 2-digit binary code in bit field 11-12 of the channel configuration
word. A lower filter frequency increases the channel update time, but
also increases the noise rejection and channel resolution. A higher
filter frequency decreases the channel update time, but also decreases
the noise rejection and effective resolution.
7. If an RTD or resistance input type was selected, enter the digit binary
code corresponding to 2- or 4-wire, or 3-wire, RTD inputs in bit 13. If
a thermocouple, mV, V, or mA type is used, enter a 0 in bit 13.
8. If auto-calibration is desired, place a zero in bit 14. If auto-calibration
is not desired, place a one in bit 14.
9. Determine whether the channel input image word should contain data
or status. Place a one in bit 15 if channel data is desired. Place a zero
in bit 15 if status is desired.
10. Build the channel configuration word for every channel on each
universal module repeating the procedures given in steps
1-9.
11.Enter this configuration into your ladder program and copy it to the
universal module.
Each channel has a word in the module’s output image which determines
the way that channel functions. Channels 0 through 3 may be configured
for current, voltage or thermocouple input types. No RTD or resistance
input types are allowed on those channels. Channels 4 through 7 may be
configured for current, voltage, thermocouple, RTD or resistance inputs.
The definition of the bits in the configuration words are described in the
charts below.
36SLC 500™ Universal Analog Input Module
Table 4.1Channel Configuration Word (O:e.3:0)
Channel 3:015 14 13 12 11 10987 654321 0
ChannelChannel disable0
EnableChannel enable1
4 to 20 mA00000
0 to 20 mA00001
± 0.05 V00010
± 0.10 V00011
± 0.50 V00100
± 2.0 V00101
Input1 to 5V00111
Type0 to 10V01000
DataEngineering Units x1001
FormatScaled for PID10
OpenMax. on open circuit01
CircuitMin. on open circuit10
TemperatureDegrees C0
UnitsDegrees F1
Channel10 Hz input filter00
filter50 Hz input filter01
freq.60 Hz input filter10
Unused0
Auto-calEnabled0
Input ImageStatus word0
TypeData word1
0 to 5 V00110
±10V01001
Thermocouple Type J01010
Thermocouple Type K01011
Theromcouple Type T01100
Thermocouple Type E01101
Thermocouple Type R01110
Thermocouple Type S01111
Thermocouple Type B10000
Thermocouple Type N10001
Invalid1001x
Invalid101xx
Invalid110xx
Invalid1110x
Thermocouple Type C11110
CJC11111
Engineering Units x100
Proportional counts11
Zero on open circuit00
Disabled11
250 Hz input filter11
Disabled1
Chapter 4: Channel Configuration, Data, and Status37
Table 4.2Channel Configuration Word (O:e.7:4)
Channel 7:415 14 13 12 11 109876543210
ChannelChannel disable0
EnableChannel enable1
Input1 to 5 V00111
Type0 to 10 V01000
DataEngineering Units x1001
FormatScaled for PID10
OpenMax. on open circuit01
CircuitMin. on open circuit10
TemperatureDegrees C0
UnitsDegrees F1
Channel10 Hz input filter00
filter50 Hz input filter01
freq.60 Hz input filter10
RTD Type2 or 4 wire0
Auto-calEnabled0
Input ImageStatus word0
TypeData word1
The configuration word default setting is all zeros. Whan a voltage or current input type is selected, the bit setting for
temperature units is ignored.
4 to 20 mA00000
0 to 20 mA00001
± 0.05 V00010
± 0.10 V00011
± 0.50 V00100
± 2.0 V00101
0 to 5 V00110
±10V01001
Thermocouple Type J01010
Thermocouple Type K01011
Thermocouple Type T01100
Thermocouple Type E01101
Thermocouple Type R01110
Thermocouple Type S01111
Thermocouple Type B10000
Thermocouple Type N10001
Use the channel enable bit to enable a channel. The universal module only
scans those channels that are enabled. To optimize module operation and
minimize throughput times, unused channels should be disabled by setting
the channel enable bit to zero.
When set (1) the channel enable bit is used by the module to read the
configuration word information you have selected. While the enable bit is
set, modification of the configuration word may lengthen the module
update time for one cycle. If any change is made to the configuration
word, the change will be reflected in the status word before new data is
valid (described in the last section of this chapter).
While the channel enable bit is cleared (0), the associated channel data/
status word values are cleared. After the channel enable bit is set, the
associated channel data/status word remains cleared until the universal
module sets the channel status bit (bit 0) in the channel status word.
Select Input Types (Bits 1-5)
The input type bit field lets you configure the channel for the type of input
device you have connected to the module. Valid input devices are types J,
K, T, E, R, S, B, N, and C thermocouple sensors, 100Ω, 200Ω, 500Ω, and
1000Ω Pt 385 RTDs; 100Ω, 200Ω, 500Ω, and 1000Ω Pt 3916 RTDs; 10Ω
Cu 426 RTD, 120Ω Ni 618 RTD, and 120Ω Ni 672 RTD sensors; 3000Ω
resistance devices and ±50mV, ± 100mV, ±500mV, ±2V, 0-5V, 1-5V, 010V, ±10V, 0-20mA, and 4-20mA analog input signals. The channel can
also be configured to read the cold-junction temperature calculated for that
specific channel. When the cold-junction compensation (CJC)
temperature is selected, the channel ignores the physical input signal.
RTD and resistance inputs can only be supported by channels 4-7.
Select Data Format (Bits 6 and 7)
The data format bit field lets you define the expressed format for the
channel data word contained in the module input image. The data types
are engineering units, scaled-for-PID, and proportional counts.
The engineering units allow you to select from two resolutions, x1 or
x10. For engineering units x1, values are expressed in 0.1 degrees,
0.01mV or 0.001mA. For engineering units x10, values are expressed in
1.0 degrees, 1mV or 0.01mA. (Use the x10 setting to produce
temperature readings in whole degrees Celsius or Fahrenheit.) You will
notice in Table 11 that not all input types can support the x1 format.
The scaled-for-PID value is the same for millivolt, milliamp,
thermocouple, RTD, resistance,) and CJC input types. The input signal
range is proportional to your selected input type and scaled into a 0-16,383
range, which is standard to the SLC PID algorithm.
Chapter 4: Channel Configuration, Data, and Status39
The proportional counts are scaled to fit the defined temperature,
voltage, or current range. The input signal range is proportional to your
selected input and scaled into a (-32,768 to 32,767) range.
Using Scaled-for-PID and Proportional Counts
The universal module provides eight options for displaying input channel
data. These are 0.1°F, 0.1°C, 1°F, 1°C, 0.01 mV, 0.1 mV, Scaled-for-PID,
and Proportional Counts. The first six options represent real Engineering
Units provided/displayed by the 1746sc-NI8u, and do not require
explanation. The Scaled-for-PID and Proportional Counts selections
provide the highest NI8u display resolution, but also require you to
manually convert the channel data to real Engineering Units.
The equations below show how to convert from Scaled-for-PID to
Engineering Units, Engineering Units to Scaled-for-PID, Proportional
Counts to Engineering Units, and Engineering Units to Proportional
Counts. To perform the conversions, you must know the defined
temperature or millivolt range for the channel’s input type. Refer to the
Channel Data Word Format table on the following page. The lowest
possible value for an input type is S
.
S
HIGH
, and the highest possible value is
LOW
It is important to note that the Scaled for PID and proportional counts
format do not linearize inputs that are not linear. The module assumes that
current and voltage inputs are linear prior to insertion into the universal
module’s input stage. Thermocouple inputs are cold junction compensated,
and are linearized in their temperature conversion process through the
NIST ITS-90 tables. RTDs are converted from their resistance value to
degrees according to their associated IEC or JISC standards.
Scaling ExamplesScaling Examples
Scaling Examples
Scaling ExamplesScaling Examples
Scaled-for-PID to Engineering Units
Equation:Engr Units Equivalent = S
Solution:Engr Units Equivalent = -210°C + [(760°C-(-210°C)) x (3421/16384)] = -7.46°C.
+ [(S
LOW
Assume type J input type, scaled-for-PID display type, channel data = 3421.
Want to calculate °C equivalent.
From Channel Data Word Format table, S
HIGH-SLOW)
x (Scaled-for-PID value displayed/16384)]
= -210°C and S
LOW
HIGH
Engineering Units to Scaled-for-PID
Equation:Scaled-for-PID Equivalent = 16384 x [(Engineering Units desired -S
LOW
)/(S
HIGH-SLOW
)]
= 760°C.
Assume type J input type, scaled-for-PID display type, desired channel
4-20 mA *+400 to +2,000+4,000 to +20,0000 to 16,383-32,768 to 32,767
0-20 mA *0 to +2,000+0 to +20,0000 to 16,383-32,768 to 32,767
± 0.05 V *-500 to +500-5,000 to +5,0000 to 16,383-32,768 to 32,767
± 0.10 V *-1,000 to +1,000-10,000 to +10,0000 to 16,383-32,768 to 32,767
± 0.50 V *-5,000 to +5,000N/A0 to 16383-32,768 to 32,767
± 2.0 V *-2,000 to +2,000-20,000 to +20,0000 to 16,383-32,768 to 32,767
0-5 V *0 to +5,000N/A0 to 16,383-32,768 to 32,767
1-5 V *+1,000 to +5,000N/A0 to 16,383-32,768 to 32,767
0-10 V *0 to +10,000N/A0 to 16,383-32,768 to 32,767
±10 V *-10,000 to +10,000N/A0 to 16,383-32,768 to 32,767
J-210 to 760-346 to 1,400-2,100 to 7,600-3,460 to 14,0000 to 16,383-32,768 to 32,767
K-270 to 1,370-454 to 2,498-2,700 to 13,700-4,540 to 24,9800 to 16,383-32,768 to 32,767
T-270 to 400-454 to 752-2,700 to 4,000-4,540 to 7,5200 to 16,383-32,768 to 32,767
E-270 to 1,000-454 to 1,832-2,700 to 10,000-4,540 to 18,3200 to 16,383-32,768 to 32,767
R0 to 1,76832 to 3,2140 to 17,680320 to 32,1400 to 16,383-32,768 to 32,767
S0 to 1,76832 to 3,2140 to 17,680320 to 32,1400 to 16,383-32,768 to 32,767
B300 to 1,820572 to 3,3083,000 to 18,2005,720 to 32,767**0 to 16,383-32,768 to 32,767
N0 to 1,30032 to 2,3720 to 13,000320 to 23,7200 to 16,383-32,768 to 32,767
C0 to 231532 to 41990 to 23,15032 to 32767**0 to 16,383-32, 768 to 32-767
10Ω Cu 426-100 to 260-148 to 500-1,000 to 2,600-1,480 to 5,0000 to 16,383-32, 768 to 32-767
120 Ω Ni 618-100 to 260-148 to 500-1,000 to 2,600-1,480 to 5,0000 to 16,383-32, 768 to 32-767
120 Ω Ni 672-80 to 260-112 to 500-800 to 2,600-1,120 to 5,0000 to 16,383-32, 768 to 32-767
3000Ω*0 to 3,0000 to 30,0000 to 16,383-32, 768 to 32-767
100Ω Pt 385-200 to 850-328 to 1,562-2,000 to 8,500-3,280 to 15,6200 to 16,383-32,768 to 32,767
200Ω Pt 385-200 to 750-328 to 1,382-2,000 to 7,500-3,280 to 13,8200 to 16,383-32,768 to 32,767
500Ω Pt 385-200 to 850-328 to 1,562-2,000 to 8,500-3,280 to 15,6200 to 16,383-32,768 to 32,767
1,000Ω Pt 385-200 to 850-328 to 1,562-2,000 to 8,500-3,280 to 15,6200 to 16,383-32,768 to 32,767
100Ω Pt 3916-200 to 630-328 to 1,166-2,000 to 6,300-3,280 to 11,6600 to 16,383-32,768 to 32,767
200Ω Pt 3916-200 to 630-328 to 1,166-2,000 to 6,300-3,280 to 11,6600 to 16,383-32,768 to 32,767
500Ω Pt 3916-200 to 630-328 to 1,166-2,000 to 6,300-3,280 to 11,6600 to 16,383-32,768 to 32,767
1,000Ω Pt 3916-200 to 630-328 to 1,166-2,000 to 6,300-3,280 to 1,16600 to 16,383-32,768 to 32,767
C JC-25 to 105-13 to 221-250 to 1,050-130 to 2,2100 to 16,383-32,768 to 32,767
* When current, voltage, or resistance input types are selected, the temperature setting is ignored and does not affect the data format.
** When Type B or Type C thermocouples cannot be represented in engineering units x 1 in °F above 3276.6°F, the module’s software will treat it as an
over range condition if that channel has input to full scale.
42SLC 500™ Universal Analog Input Module
Table 4.41746sc-NI8u Thermocouple Module -
Channel Data Word Resolution
Data Format
InputEngineering Units x 10 Engineering Units x 1Scaled-for-PIDProportional Counts
Type° Celsius° Fahrenheit° Celsius° Fahrenheit° Celsius° Fahrenheit° Celsius° Fahrenheit
When millivolts or resistance are selected, the temperature setting is ignored. Analog input data is the same for either °C or °F selection.
Chapter 4: Channel Configuration, Data, and Status43
Important: Data resolution is not equivalent to data accuracy. Data
resolution merely indicates what a bit-weight is in any given
input type and data format combination. Input accuracy of
±50µV may span multiple steps for PID and Proportional
Counts data types. As an example a Type B thermocouple
temperature range of 0 to 1820°C provides a voltage input
range of 0 to 13.82mV to the NI8u. This is a very small
input range and when it is scaled to PID or proportional
counts ranges a small input change will result in many
counts being changed.
Select Open Circuit State (Bits 8 and 9)
The open-circuit bit field lets you define the state of the channel data word
when an open-circuit condition is detected for that channel. The open
circuit does not apply to the 0-5V, 1-5V, 0-10V, ±2V, ±10V, or 0-20mA
input types and should be disabled when those types are selected, or else a
configuration error will result. It can be enabled for all other types,
including the CJC input. This feature can be disabled by selecting the
disable option.
An open circuit condition occurs when the input path is physically
separated or open. For thermocouples or RTDs, either the sensor or the
extension wire may be broken. The voltage or current input wire may be
cut or disconnected from the terminal block. For RTDs only, a short
circuit of less than 3 ohms will also flag this error.
If either of the two CJC devices are removed from the module wiring
terminal, any input channel configured for either a thermocouple or CJC
temperature input will be placed in an open circuit condition. An input
channel configured for millivolt, volt, milliamp, or RTD input is not affected
by CJC open-circuit conditions.
The results of the data word in an open-circuit condition depend upon the
selection of bits 8 and 9.
If zero is selected, the channel data word is forced to 0 during an opencircuit condition.
Selecting maximum forces the channel data word value to its full scale
value during an open-circuit condition. The full scale value is determined
by the selected input type and data format.
Selecting minimum forces the channel data word value to its low scale
value during an open-circuit condition. The low scale value is determined
by the selected input type and data format.
When the open-circuit option applies, disabling the open-circuit selection
may result in unintended operation on a failure because the returned data
word value is unknown. The open circuit error bit and the channel LED
will flag the condition until the error is resolved.
44SLC 500™ Universal Analog Input Module
For example, if channel one is configured as a thermocouple type when
the CJC breaks in an open-circuit condition, if open-circuit detection is
disabled, the data word will remain unchanged. If the circuit selection is
set at minimum, the data word will be set to the low scale value for the
range and format.
Select Temperature Units (Bit 10)
The temperature units bit lets you select temperature engineering units for
thermocouple, RTD, and CJC input types. Units are either degrees
Celsius (°C) or degrees Fahrenheit (°F). This bit field is only active for
thermocouple, RTD and CJC input types. It is ignored when millivolt or
current inputs types are selected.
Select Channel Filter Frequency (Bits 11 and 12)
The channel filter frequency bit field lets you select one of four filters
available for a channel. The filter frequency affects the channel update
time and noise rejection characteristics. A smaller filter frequency
increases the channel update time, but also increases the noise rejection
and channel resolution. A larger filter frequency decreases the noise
rejection, but also decreases the channel update time and channel
resolution.
• 60 Hz setting provides 60 Hz AC line noise filtering.
• 50 Hz setting provides 50 Hz AC line noise filtering.
• 10 Hz setting provides both 50 Hz and 60 Hz AC line noise filtering.
When a CJC input type is selected, this field is ignored. To maximize the
speed versus resolution trade-off, CJC inputs are sampled at 60 Hz.
Select RTD Type (Bit 13)
The selection for RTD or resistance type is only valid for channels 4
through 7, and should be set to zero for channels 0 through 3.
If the Input Type selection defines an RTD or resistance type, then the
wire type also needs to be specified. The universal module converts the
RTD or resistance type input data differently according to whether the 2
or 4 wire method is used, or the 3 wire method is used.
Select Auto-Calibration Disable (Bit 14)
The auto-calibration disable bit allows you to disable periodic autocalibration. Set this bit on any enabled channel to disable auto-calibration
for all channels. Clear this bit on all enabled channels to enable autocalibration on all channels.
Channel Data/Status
Word
Module Input Image (Data/Status) Words
O:e.0
Chapter 4: Channel Configuration, Data, and Status45
Select Input Image Type (Bit 15)
The input image type bit allows you to select data or status information in
the channel’s input image word. When set (1) the module places channel
data in the corresponding input image word. When the bit is cleared (0)
the module places channel status in the corresponding input image word.
The actual thermocouple, RTD, resistance, millivolt, volt, or milliamp input
data values or channel status reside in I:e.0 through I:e.7 of the universal
module input image file. The data values present will depend on the input
type and data formats you have selected. When an input channel is
disabled, its data word is reset (0).
15
Channel 0 Channel Data/Status Word
0
O:e.2
O:e.3
O:e.4
O:e.5
O:e.6
O:e.7
Channel Status
Checking
Channel 1 Channel Data/Status WordO:e.1
Channel 2 Channel Data/Status Word
Channel 3 Channel Data/Status Word
Channel 4 Channel Data/Status Word
Channel 5 Channel Data/Status Word
Channel 6 Channel Data/Status Word
Channel 7 Channel Data/Status Word
The input image of the module is 8 words. Since there are 8 channels
with a data word and a status word for each channel, the input image
information is multiplexed. The information in the input image is the
channel data word if bit 15 of the channel’s configuration word is 1. The
information in the input image is the channel status word if bit 15 of the
channel’s configuration word is 0.
You can use the information provided in the status word to determine if the
input configuration data for any channel is valid per your configuration in
O:e.0 through O:e.7.
46SLC 500™ Universal Analog Input Module
The channel status can be analyzed bit by bit. In addition to providing
information about an enabled or disabled channel, each bit’s status (0 or 1)
tells you how the input data from the analog sensor connected to a
specific channel will be translated for your application. The bit status also
informs you of any error condition and can tell you what type of error
occurred.
The status word definitions for channels 0 through 3 do not include the
RTD or resistance support that is provided by channels 4 through 7. The
charts on the following pages provide a bit by bit examination of the
respective status words.
Table 4.5Channel 0-7 Status Word (I:e.0 through
I:e.7) - Bit Definitions
Channel 3:015 14 13 12 11 10 9876543210
ChannelChannel disabled0
StatusChannel enable1
Input1 to 5V0011 1
Type0 to 10V0100 0
DataEngineering Units x1001
FormatScaled for PID10
OpenMax. on open circuit01
CircuitMin. on open circuit10
Channel10 Hz input filter00
filter50 Hz input filter01
freq.60 Hz input filter10
Open circuitNo error0
Under rangeNo error0
errorUnder range condition1
Over rangeNo error0
errorOver range condition1
Channel No error0
errorChannel error1
4 to 20 mA00000
0 to 20 mA00001
± 0.05 V0001 0
± 0.10 V0001 1
± 0.50 V0010 0
± 2.0 V0010 1
0 to 5 V0011 0
±10V0100 1
Thermocouple Type J01010
Thermocouple Type K01011
Theromcouple Type T01100
Thermocouple Type E01101
Thermocouple Type R01110
Thermocouple Type S01111
Thermocouple Type B10000
Thermocouple Type N10001
Invalid1001 x
Invalid101x x
Invalid110x x
Invalid1110 x
Thermocouple Type C11110
CJC temperature11111
Engineering Units x100
Proportional counts11
Zero on open circuit00
Disabled11
250 Hz input filter11
Open circuit detected1
Chapter 4: Channel Configuration, Data, and Status47
OpenMax. on open circuit01
CircuitMin. on open circuit10
Channel10 Hz input filter00
filter50 Hz input filter01
freq.60 Hz input filter10
Open circuitNo error0
Under rangeNo error0
errorUnder range condition1
Over rangeNo error0
errorOver range condition1
Channel No error0
errorChannel error1
0 to 5 V0011 0
±10V0100 1
Thermocouple Type J01010
Thermocouple Type K01011
Thermocouple Type T01100
Thermocouple Type E01101
Thermocouple Type R01110
Thermocouple Type S01111
Thermocouple Type B10000
Thermocouple Type N10001
Important: If the channel for which you are seeking status is disabled,
all bit fields are cleared. The status word for any disabled
channel is always 0000 0000 0000 0000 regardless of any
previous setting that may have been made to the
configuration word.
Explanations of the status conditions follow.
Channel Status (Bit 0)
The channel status bit indicates operational state of the channel. When
the channel enable bit is set in the configuration word (bit 0), the universal
module configures the selected channel and takes a data sample for the
channel data word before setting this bit in the status word.
Input Type Status (Bits 1-5)
The input type bit field indicates what type of input signal you have
configured for the channel. This field reflects the input type defined in the
channel configuration word.
Data Format Type Status (Bits 6 and 7)
The data format bit field indicates the data format you have defined for
the channel. This field reflects the data type selected in bits 6 and 7 of the
channel configuration word.
Open Circuit Type Status (Bits 8 and 9)
The open-circuit bit field indicates how you have defined the open circuit
bits configuration word, and therefore, the response of the universal
module to an open-circuit condition. This feature does not apply to the 0-5
V, 1-5 V, 0-10 V, ±2 V, ±10 V, or 0-20mA input ranges, and a properly
configured channel of those types will give the disabled status. It applies
to all others, including CJC temperature input.
Channel Filter Frequency (Bits 10 and 11)
The channel filter frequency bit field reflects the filter frequency you
selected in the configuration word.
Open Circuit Error (Bit 12)
This bit is set (1) whenever a configured channel detects an open-circuit
condition at its input. Short circuited RTD inputs will also flag this error
condition. A short circuit for RTDs exist when the module reads less than
3 ohms across the RTD input. An open-circuit at the CJC sensor will also
flag this error if the channel input type is either thermocouple or CJC
temperature. A range error on the CJC sensor will also flag this bit if the
input type is a thermocouple type.
Chapter 4: Channel Configuration, Data, and Status49
Under-Range Error (Bit 13)
This bit is set (1) whenever a configured channel detects an under-range
condition for the channel data. An under-range condition exists when the
input value is equal to or below the specified lower limit of the particular
sensor connected to that channel.
Over-Range Error (Bit 14)
This bit is set (1) whenever a configured channel detects an over-range
condition for the channel data. An over-range condition exists when the
input value is equal to or above the specified upper limit of the particular
sensor connected to that channel.
Channel Error (Bit 15)
This bit is set (1) whenever a configured channel detects an error in the
configuration word, or an error has occurred while acquiring the ADC
data value. If during the auto-calibration process, the module detects an
out-of-range condition for the filter frequency selected for the channel, the
channel error bit will be set. An out-of-range condition occurring during
auto-calibration would be the result of an overly noisy environment,
whereby the module cannot maintain accuracy specifications, thus flagging
an error. The error bit is cleared when the error condition is resolved.
The channel data word is still updated during a period of auto-calibration
filter frequency tolerance errors, but accuracy may be degraded.
50SLC 500™ Universal Analog Input Module
Chapter 5: Ladder Program Examples51
Chapter 5
Programming Examples
Earlier chapters explained how the configuration word defines the way a
channel operates. This chapter shows the programming required to
enter the configuration word into the processor memory. It also
provides you with segments of ladder logic specific to unique situations
that might apply to your programming requirements. The example
segments include:
• initial programming of the configuration word
• dynamic programming of the configuration word
• verifying channel configuration changes
• interfacing the universal module to a PID instruction
• monitoring channel status bit
Initial Programming
To enter data into the channel configuration word (O:e.0 through O:e.7)
when the channel is disabled (bit 0 = 0), follow these steps. Refer to
page 30 (Table 9) for specific configuration details.
Example - Configure eight channels of a universal module residing in
slot 3 of a 1746 chassis. Configure each channel with the same
parameters.
Figure 5.1Channel configuration
1514131211109876543210
10000011 01010011
Configure Channel For:
Channel Enable Bit
± 10.0 V Range
Engineering Units x 10
Open Circuit Disabled
Degrees C (N/A)
10 Hz Filter
RTD Type (N/A)
Auto-cal Disable Bit
Channel Data Word
This example transfers configuration data and sets the channel enable
bits of all eight channels with a single File Copy instruction.
52SLC 500™ Universal Analog Input Module
Procedure
1. Using the memory map function, create integer file N10. Integer file
N10 should contain eight elements (N10:0 through N10:7).
2. Using the APS software data monitor function, enter the
configuration parameters for all eight universal channels into a source
integer data file N10.
Press a key or enter value
N10:3/0 = 1
offlineno forcesbinary datadecimal addrFile EXMPL
CHANGE
RADIX
F1
SPECIFY
ADDRESS
F5
NEXT
FILE
F7
PREV
FILE
F8
3. Program a rung in your ladder logic to copy the contents of integer
file N10 to the eight consecutive output words of the universal
module beginning with O:3.0.
Figure 5.3Initial programming example
First Pass Bit
s:1
] [
15
Initialize Module
COP
COPY FILE
Source #N10:0
Length 8
Dest #O:3.0
On power up, bit S:1/15 is set for the first program scan, and integer file N10
is sent to the NI8u channel configuration words.
Dynamic
Programming
Chapter 5: Ladder Program Examples53
The following example explains how to change data in the channel
configuration word when the channel is currently enabled.
Example - Execute a dynamic configuration change to channel 2 of the
universal module located in slot 3 of a 1746 chassis. Change from
monitoring a bipolar 10 V signal to monitoring the CJC sensors
mounted on the terminal block. This gives a good indication of what
the temperature is inside the control cabinet. Finally, set channel 2 back
to the bipolar 10 V range.
Important: While the module performs the configuration alteration, it
does not monitor input device data change at any channel.
Verifying Channel
Configuration
Changes
When executing a dynamic channel configuration change, there will
always be a delay from the time the ladder program makes the change
to the time the NI8u gives you a data word using that new configuration
information. Therefore, it is very important to verify that a dynamic
channel configuration change took effect in the module, particularly if
the channel being dynamically configured is used for control. The
following example explains how to verify that channel configuration
changes have taken effect.
Example - Execute a dynamic configuration change to channel 2 of the
universal module located in slot 3 of a 1746 chassis, and set an internal
“data valid” bit when the new configuration has taken effect. In this
example the input image of the channel is selected to contain the
channel status word.
Chapter 5: Ladder Program Examples55
Figure 5.6Programming for configuration changes
example
Rung 2:0
Rung 2:1
Rung 2:2
Rung 2:3
Set up all eight channels
s:1
] [
15
Set channel 2 to CJC
I:1.0
] [
0
Set channel 2 back to ±10V
I:1.0
]/[
0
Check that the configuration written to channel two
is being echoed back in channel two's status word.
The universal module was designed to interface directly to the SLC
5/02™ or later processor PID instruction without the need for an
immediate scale operation.
Example - Use NI8u channel data as the process variable in the PID
instruction.
1. Select scaled-for-PID as the data type in the channel configuration
word.
2. Specify the input channel data word as the process variable for the
PID instruction.
In this example, the value -32,617 is the numeric equivalent of
configuration word N10:0 for channel 0. It is configured for a type K
thermocouple, scaled-for-PID, zero the signal for an open circuit, 10
Hz, °C, channel enabled, to return the data word.
Figure 5.8Programming for PID Control Example
Program Listing
Rung 2:0
Rung 2:1
Rung 2:2
Rung 2:3
First Pass BitInitialize NI8u
s:1
] [
15
PID
PID
Control BlockN11:0
Process VariableI:3.0
Control VariableN11:23
Control Block Length23
The Rate and Offset parameters should be set per
your application. The Dest will typically be an
analog output channel. Refer to the APS User Manual
or Analog I/O Modules User Manual for specific
examples of the SLC instruction.
Channel 0
MOV
MOVE
Source N10:0
Dest O:3.0
SCL
SCALE
Source N11:23
Rate [/10000]
Offset
Dest
-32,617
0
END
I
I
address 15 data 0 address 15 data 0
N10:0 1000 0000 1001 0111
Monitoring Channel
Status Bits
Chapter 5: Ladder Program Examples57
Figure 5.9Data table for PID Control
Data Table
The example shows how you could monitor the open circuit error bits of
each channel and set an alarm in the processor if one of the inputs
opens. An open circuit error can occur if one of the input signal wires
gets cut or disconnected from the terminal block, or if the CJC sensors
are not installed or are damaged.
Important: If a CJC input is not installed or is damaged, all
thermocouple alarms are set, and their respective channel LEDs blink.
58SLC 500™ Universal Analog Input Module
Figure 5.10Monitoring channel status bits example
Program Listing
Rung 2:0
Rung 2:1
First Pass BitInitialize NI8u
s:1
] [
15
Channel 0
Enable
I:3.0
] [
0
Channel 0
Open
I:3.0
] [
12
COP
COPY FILE
Source #N10:0
Dest #O:3.0
Length 8
Channel 0
Channel 0
Alarm
O:2.0
( )
0
Rung 2:2
Rung 2:3
Rung 2:4
Rung 2:5
Rung 2:6
Rung 2:7
Channel 1
Enable
I:3.1
] [
0
Channel 2
Enable
I:3.2
] [
0
Channel 3
Enable
I:3.3
] [
0
Channel 4
Enable
I:3.4
] [
0
Channel 5
Enable
I:3.5
] [
0
Channel 6
Enable
I:3.6
] [
0
Channel 1
Open
I:3.1
] [
12
Channel 2
Open
I:3.2
] [
12
Channel 3
Open
I:3.3
] [
12
Channel 4
Open
I:3.4
] [
12
Channel 5
Open
I:3.5
] [
12
Channel 6
Open
I:3.6
] [
12
Channel 1
Alarm
O:2.0
( )
1
Channel 2
Alarm
O:2.0
( )
2
Channel 3
Alarm
O:2.0
( )
3
Channel 4
Alarm
O:2.0
( )
4
Channel 5
Alarm
O:2.0
( )
5
Channel 6
Alarm
O:2.0
( )
6
Rung 2:8
Channel 7
Enable
I:3.7
] [
0
Channel 7
Open
I:3.7
] [
12
Channel 7
Alarm
O:2.0
( )
7
Figure 5.11Data table for monitoring channel status
This is an example of how to automatically switch between reading the
channel status words and channel data words. Specifically, this
example shows a very simple method of utilizing a timer to periodically
switch between reading the channel status and data words.
The program utilizes a timer accumulator value to determine when to
set up the configuration words, and when to read in the channel status
and channel data information. The channel status information is copied
from the I:2.0 to I:2.7 registers into registers N7:10 to N7:17. The
channel data information is copied from I:2.0 to I:2.7 into registers N7:0
to N7:7. This allows sensor data and channel status information to be
accessed at any time from these registers. However, when the module
channels are configured to read sensor data, the channel status words
(as reflected in N7:10 to N7:17) are not being dynamically updated, and
vice-versa.
A longer interval between reading in the channel status information
could be achieved through the utilization of a combination of counters
and timers. If you are utilizing an SLC 5/03 or SLC 5/04 or later
processor, the internal processor clock registers S:40 to S:42 could be
utilized to determine the timing.
Rung 2:0
TON
TIMER ON DELAY
Timer T4:0
Timer Base 0.01
Preset 1001
Accum 0
(EN)
(DN)
Timer T4:0 counts out a 10 second interval. Its accumulator indicates
the progress it has made toward completion. The accumulator value
shall be utilized to determine when to set the channel configuration
word to send sensor data or to send status information.
A longer interval between transitions can be achieved using a
combination of timers and counters.
60SLC 500™ Universal Analog Input Module
Rung 2:1
This rung tests to see if T4:0.ACC is at a value between 800 and 950
counts. If so, the channel configuration words are defined (through the
Fill File command) to send status information.
LIM
LIMIT TEST
Low Lim 800
Test T4:0.ACC
0
High Lim950
FLL
FILL FILE
Source 151
Dest #O:2.0
Length 8
Rung 2:2
This rung executes a Copy File command to move the channel status
word (as enabled in the previous rung) into registers N7:10 through
N7:17 for all channels.
Though the module is quick about switching from sensor data to status
information, it is a good idea to give the module a little time to switch
modes. That is why this example uses a half second period in time
between when the channel is set-up to send the status word and when
the status word is read into the N7 table.
LIM
LIMIT TEST
Low Lim 950
Test T4:0.ACC
0
High Lim1000
COP
COPY FILE
Source #I:2.0
Dest #N7:10
Length 8
Chapter 5: Ladder Program Examples61
Rung 2:3
This rung will copy the channel sensor data into registers N7:0 through
N7:7, about 2 seconds after the configuration word has been changed to
send sensor data.
Timing is important here. Because the channels are multiplexed, it can
take the module some amount of time to update the channel input word
with sensor data it has been sending channel status information. That
amount of time is determined by the module update time and the worst
case autocalibration time that could occur based on the filter frequencies
and input types selected.
LIM
LIMIT TEST
Low Lim 200
Test T4:0.ACC
0
High Lim750
COP
COPY FILE
Source #I:2.0
Dest #N7:0
Length 8
Rung 2:4
This rung will set the channel configuration words for sending sensor
data, each time the timer completes a cycle. It also resets the timer.
T4:0
] [
DN
FLL
FILL FILE
Source -32617
Dest #O2:0
Length 8
T4:0
(RES)
Rung 2:5
|END|
62SLC 500™ Universal Analog Input Module
Chapter 6
Testing Your Module
This chapter describes troubleshooting with channel-status and modulestatus LEDs. It explains the types of conditions that might cause the
module to flag an error, and suggests what corrective action you could
take. Topics include:
• module and channel diagnostics
• LED indicators
• Interpreting I/O error codes
• troubleshooting flowchart
Module and Channel
Diagnostics
The module operates at two levels:
• module level
• channel level
Module level operation includes functions such as power-up, configuration,
and communication with the SLC processor. ON indicates the module is
OK. OFF indicates a fault.
Channel level operation includes functions such as data conversion and
open-circuit detection. ON indicates the channel is OK. Blinking
indicates a fault.
The module performs internal diagnostics at both levels, and immediately
indicates detected error conditions with either of its status LEDs. When a
status LED is continuously ON, the status is OK.
Module Diagnostics at Power-up
At module power-up, the module performs a series of internal diagnostic
tests. If the module detects a failure, its module status LED remains off.
Channel Diagnostics
When a channel is enabled, the module checks for a valid configuration.
Then on each scan of its inputs, the module checks for out-of-range and
open-circuit fault conditions of its inputs including the CJC input.
When the module detects a failure of any channel diagnostic test, it causes
the channel status LED to blink and sets the corresponding channel fault
64SLC 500™ Universal Analog Input Module
bit (bits 12-15 of the channel status word). Channel fault bits and LEDs
are self-clearing when fault conditions are corrected.
Important: If you clear the channel enable bit, channel status bits are
reset.
LED Indicators
The module has nine LEDs:
• eight channel-status LEDs, numbered to correspond with each channel
• one module-status LED
INPUT
Status
014
236
5
7
LEDs for Channels 0-7
Channel
LED for Module Status
Module
Universal Analog
LED Troubleshooting Tables
Table 6.1Module-status LED
If Module
Status LED is:Then:Take this Corrective Action:
OnThe module is OK.No action required.
Of fThe module is turned off,Cycle power. If the condition persists,
or it detected a modulecall your local distributor or Spectrum
fault.Controls for assistance.
Table 6.2Module-status and Channel-status LED
If Module
StatusAnd ChannelThen:Take this Corrective Action:
LED is:Status LED is:
OnThe channelNo action required.
is enabled.
BlinkingThe moduleExamine error bits in status word
detected:if bit 12=1, the input has an open circuit
Onopen-circuit conditionif bit 13=1, the input value is under range
under-range conditionif bit 14=1, the input value is over range
over-range conditionif bit 15=1, the channel has a diagnostic
channel erroror channel error
OffThe module is inNo action is required.
power up, or the
channel is disabled.
Chapter 6: Testing Your Module65
Channel-status LEDs (Green)
The channel-status LED operates with status bits in the channel status
word to indicate the following faults detected by the module:
• invalid channel configuration
• an open-circuit input
• out-of-range errors
• selected filter frequency data acquisition or auto-calibration errors
When the module detects any of the following fault conditions, it causes
the channel-status LED to blink and sets the corresponding fault bit in the
channel status word. Channel fault bits (bits 12-15) and channel-status
LEDs are self-clearing when fault conditions are corrected.
Open-circuit Detection (Bit 12)
If open-circuit is enabled for an applicable input channel, the module tests
the channel for an open-circuit condition each time it scans its input.
Open-circuit detection is always performed for the CJC inputs. Open
circuit does not apply to ±2V, 0-5V, 1-5V, ±10V, 0-10V, or 0-20mA ranges.
Possible causes of an open circuit include:
• broken thermocouple, RTD or CJC sensor
• thermocouple, RTD or CJC sensor wire cut or disconnected
• millivolt, volt or milliamp input wire cut or disconnected
• less than 3 ohms has been detected on an RTD input.
Out-of-Range Detection (Bit 13 for under range, bit
14 for over range)
The module tests all enabled channels for an out-of-range condition each
time it scans its inputs. Possible causes of an out-of-range condition
include:
• the temperature is too hot or too cold for the thermocouple or RTD
being used
• a type B thermocouple may be registering a °F value in EU x1 beyond
the range allowed by the SLC processor (beyond 32,767) for the data
word
• a CJC sensor may be damaged or the temperature being detected by
the CJC may be outside the CJC sensor range limits
• the millivolt, Volt, or milliamp input is outside of its selected input range
66SLC 500™ Universal Analog Input Module
Channel Error (Bit 15)
The module sets this fault bit when it detects any of the following:
Configuration erorrs:
- configuration bits Data Format definition, invalid Input Types for
channels 0 through 3: 10010 - 11101
- configuration bits Data Format definition of Engineering Units x 1 for
Input Types of ±500mV, 0-5V, 1-5V, 0-10V, ±10V, 0-20mA
- configuration bits where Open Circuit is enabled with Input types of 05V, 1-5V, 0-10V, ±10V, or 0-20mA
- invalid data acquisition of an input channel
- the filter frequency selected for the valid channel currently fails
autocalibration range checks
Module Status LED (Green)
Interpreting I/O Error
Codes
The module-status LED indicates when the module detects a
nonrecoverable fault at power up or during operation. For this type of
fault, the module:
• no longer communicates with the SLC processor
• disables all channels
• clears all data and status words
A module failure is non-recoverable and requires the assistance of your
local distributor or Spectrum Controls.
I/O error codes appear in word S:6 of the SLC processor status file. The
first two digits of the error code identify the slot (in hexadecimal) with the
error. The last two digits identify the I/O error code (in hexadecimal).
The error codes that apply to your module include (in hexadecimal):
• 50–5E
• 71 (watchdog error)
• 90–94
For a description of the error codes, refer to the Allen-Bradley AdvancedProgramming Software (APS) Reference Manual, Allen-Bradley
publication 1746-6.11.
Verifying With Test
Instrumentation
Chapter 6: Testing Your Module67
The 1746sc-NI8u has multiplexed channel inputs which switch in order to
read an input channel. The settling time is 3ms. Caution must be used
when testing the module with a test instrument, because the instrument
may require a settling time much greater than 3 ms. Errors will result in
the test instrument sourcing if its settling time requirement is not met.
Contact the instrumentation manufacturer for settling time requirements
before using the instrument to test your module.
68SLC 500™ Universal Analog Input Module
Figure 6.1 Troubleshooting Flowchart
Check LEDs
on module.
Module
Status LED(s)
off.
Module fault
condition.
Check to see
that module is
seated properly
in chassis.
Cycle power.
Is problem
corrected?
No
Module
Status LED
on.
Normal module
operation.
End
Ye s
End
Status LED(s)
Fault
condition.
Are
faulted channel(s)
configured for mV or
thermocouple
input?
Thermocouple
Is more than one
LED blinking?
Ye s
CJC fault
has probably
occurred
Check that wiring is secure
at both CJCs and that the
temperature within the
enclosure is in the range
limits of the CJC sensor.
(Refer to Chapter One.)
Ye s
Is problem
corrected?
No
RTD or resistance
Check channel
status word
bits 1215.
Channel
blinking.
mV, mA,
No
Bit 15
set (1)
Bit 14
set (1)
Bit 13
set (1)
Channel
Status LED(s)
off.
Channel is
not enabled.
Enable channel if
desired by setting
channel config.
word (bit 0 = 1).
Retry.
Channel error. Check
configuration word
for a valid input type
configuration and insure
bit 14 is set to zero.
Retry.
Over-range condition exists.
The input signal is greater
than the high scale limit for
the channel or the CJC
connections. Correct and
Retry.
Under-range condition exists.
The input signal is less than
the low scale limit for the
channel or the CJC
connections. Correct and
Retry.
Channel
Status LED(s)
on.
Channel is
enabled and
working.
End
Ye s
Is problem
corrected?
No
Contact you local
distributor or
Spectrum
Controls.
Contact you local
distributor or
Spectrum
Controls.
Bit 12
set (1)
An open-circuit condition is
present. Check channel and
CJC wiring for open or
loose connections. Check
for short circuited RTD
connections. Retry.
Contact you local
distributor or
Spectrum
Controls.
Chapter 7: Maintaining Your Module And Ensuring Safety69
Chapter 7
Maintaining Your Module
And Ensuring Safety
Read this chapter to familiarize yourself with:
• preventive maintenance
• safety considerations
The National Fire Protection Association (NFPA) recommends
maintenance procedures for electrical equipment. Refer to article 70B of
the NFPA for general safety-related work practices.
Preventive Maintenance
Safety Considerations
The printed circuit boards of your module must be protected from dirt,
oil, moisture, and other airborne contaminants. To protect these boards,
install the SLC 500 system in an enclosure suitable for its operating
environment. Keep the interior of the enclosure clean, and whenever
possible, keep the enclosure door closed.
Also, regularly inspect the terminal connections for tightness. Loose
connections may cause a malfunctioning of the SLC system or damage to
the components.
WARNING
!
POSSIBLE LOOSE CONNECTIONS
Before inspecting connections, always ensure that
incoming power is OFF.
Failure to observe this precaution can cause personal injury and
equipment damage.
Safety is always the most important consideration. Actively think about
the safety of yourself and others, as well as the condition of your
equipment. The following are some things to consider:
Indicator Lights – When the module status LED on your module is
illuminated, your module is receiving power.
Activating Devices When Troubleshooting – Never reach into a
machine to activate a device; the machine may move unexpectedly. Use a
wooden stick.
70SLC 500™ Universal Analog Input Module
Standing Clear Of Machinery – When troubleshooting a problem with
any SLC 500 system, have all personnel remain clear of machinery. The
problem may be intermittent, and the machine may move unexpectedly.
Have someone ready to operate an emergency stop switch.
CAUTION
!
Safety Circuits – Circuits installed on machinery for safety reasons (like
over-travel limit switches, stop push-buttons, and interlocks) should
always be hard-wired to the master control relay. These circuits should
also be wired in series so that when any one circuit opens, the master
control relay is de-energized, thereby removing power. Never modify
these circuits to defeat their function. Serious injury or equipment
damage may result.
POSSIBLE EQUIPMENT OPERATION
Never reach into a machine to actuate a switch. Also,
remove all electrical power at the main power disconnect
switches before checking electrical connections or inputs/
outputs causing machine motion.
Failure to observe these precautions can cause personal injury
or equipment damage.
WARNING
!
EXPLOSION HAZARD
SUBSTITUTION OF COMPONENTS MAY IMPAIR
SUITABILITY FOR CLASSI DIVISION2.
WARNING
!
EXPLOSION HAZARD
DO NOT DISCONNECT EQUIPMENT UNLESS POWER HAS
BEEN SWITCHED OFF OR THE AREA IS KNOWN TO BE
NON-HAZARDOUS.
NONO
TE:TE:
NO
TE: THIS EQUIPMENT IS SUITABLE FOR USE IN
NONO
TE:TE:
CLASSI, DIVISION 2, GROUPS A, B, C, AND D OR NONHAZARDOUS LOCATIONS ONLY.
Chapter 7: Maintaining Your Module And Ensuring Safety71
WARNING
!
EXPLOSION HAZARD
!
WHEN IN HAZARDOUS LOCATIONS, TURN OFF POWER
BEFORE REPLACING OR WIRING MODULES.
WARNING
!
Refer to your system’s Installation & Operation Manual for more
information.
THIS DEVICE IS INTENDED TO ONLY BE USED WITH THE
ALLEN-BRADLEY SLC500 SYSTEMS.
72SLC 500™ Universal Analog Input Module
Electrical
Specifications
Appendix A
Module Specifications
This appendix lists the specifications for the 1746sc-NI8u Universal analog
Input Module.
Backplane Current Consumption120 mA at 5 VDC
100 mA at 24 VDC
Backplane Power Consumption3.00W maximum (0.6W @ 5 VDC, 2.4W @ 24 VDC)
Number of Channels8 (backplane and channel-to-channel isolated)
I/O Chassis LocationAny I/O module slot except 0
A/D Conversion MethodSigma-Delta Modulation
Input FilteringLow pass digital filter with programmable notch (filter)
frequencies
Normal Mode Rejection (between100 dB at 50 Hz
[+] input and [-] input)100 dB at 60 Hz
Common Mode Rejection (between100 dB at 50/60 Hz
inputs and chassis ground)
Input Filter Cut-Off Frequencies
2.6 Hz at 10 Hz filter frequency
13.1 Hz at 50 Hz filter frequency
15.72 Hz at 60 Hz filter frequency
65.5 Hz at 250 Hz filter frequency
CalibrationModule autocalibrates at power-up and
approximately every two minutes afterwards*
Input Overvoltage Protection±14.5 VDC continuous
250W pulsed for 1 msec.
Input Overcurrent Protection28 mA continuous
40 mA, 1mS pulsed, 10% duty cycle maximum
Isolation500 VDC continuous between inputs and chassis
ground and between inputs and backplane.
12.5 VDC continuous between channels of TC / V / i
0 VDC between channels of RTD
* = See page 28 for detailed explanation of auto-calibration.
74SLC 500™ Universal Analog Input Module
Physical
Specifications
LED Indicators9 green status indicators, one for each of 8
Module ID Code3500
Recommended Cable:
for thermocouple inputs...Shielded twisted pair thermocouple extension wiren
for mV, V or mA inputsBelden 8761 or equivalent
for RTD inputsshielded Belden #9501, #9533, #83503o
Maximum Wire SizeOne 16 AWG wire or two 22 AWG wires per terminal
n
Refer to the thermocouple manufacturer for the correct extension wire.
o
Refer to the RTD manufacturer and Chapter 1 of this user’s manual.
EnvironmentalSpecifications
Operating Temperature0°C to 60°C (32°F to 140°F)
channels and one for module status
Input Specifications
Storage Temperature-40°C to 85°C (-40°F to 185°F)
Relative Humidity5% to 95% (without condensation)
CertificationUL & CUL approved
Hazardous EnvironmentClass1 Division 2 Hazardous Environment
ClassificationGroups A, B, C, D
EMCCE compliant
Thermocouple Type J-210°C to 760°C(-346°F to 1400°F)
Thermocouple Type K-270°C to 1370°C(-454°F to 2498°F)
Thermocouple Type T-270°C to 400°C(-454°F to 752°F)
Thermocouple Type E-270°C to 1000°C(-454°F to 1832°F)
Type of Input (Selectable) Thermocouple Type R0°C to 1768°C(32°F to 3214°F)
Thermocouple Type S0°C to 1768°C(32°F to 3214°F)
Thermocouple Type B300°C to 1820°C(572°F to 3308°F)
Thermocouple Type N0°C to 1300°C(32°F to 2372°F)
Thermocouple Type C0°C to 2315°C(32°F to 4199°F)
Millivolt (-50 mVdc to +50 mVdc)
Millivolt (-100 mVdc to +100 mVdc)
Millivolt (±500mV, ±2V, 0-5V, 1-5V, 0-10V, ±10V)
Current (4 to 20mA)
Current ( 0 to 20mA)
RTD Pt 385-200°C to 850°C-328°F to 1562°F
(100Ω, 500Ω, 1000Ω)
RTD Pt 385-200°C to 750°C-328°F to 1382°F
(200Ω)
RTD Pt 3916-200°C to 630°C-328°F to 1166°F
(100Ω, 200Ω, 500Ω, 1000Ω)
RTD 10Ω Cu 426-100°C to 260°C-148°F to 500°F
RTD 120Ω Ni 618-100°C to 260°C-148°F to 500°F
RTD 120Ω Ni 672-80°C to 260°C-112°F to 500°F
Resistance (0 to 3000Ω)
Appendix A: Module Specifications75
RTD ConversionJIS C 1602-1997 for Pt 385
JIS C 1604-1989 for Pt 3916
SAMA RC21-4-1966 for the 10Ω Cu 426 RTD
DIN 43760 Sept. 1987 for the 120Ω Ni 618 RTD
MINCO Application Aid #18 May 1990 for the 120Ω Ni 672 RTD
ThermocoupleNIST ITS-90 standard
Linearization
Channel Multiplexing3 mS
Settling Time
RTD Current Source200µA, one for each RTD channel
Cold JunctionAccuracy ±1.72°C, -25°C to +105°
CompensationOn board CJC Sensor Required, Analog Devices AD592CN
Input ImpedenceGreater than 10MΩ > Ohm Voltage / Thermocouple / RTD
< 250 Ω current
Temperature Scale°C of °F and 0.1°C or 0.1°F
(Selectable)
DC Millivolt Scale0.1 mV, 0.01 mV, or 0.001 mV
(Selectable)Depending on input type
Milliamp Scale.01 mA or .001mA
(Selectable)
Open Circuit DetectionUpscale, Downscale, Zero, or Disabled
(Selectable)Does not apply to 5 or 10V range, or 0-20mA input type
Time to DetectOne module update time
Open Circuit
Input Step Response0 to 95% in 300 msec (10 Hz)
Display ResolutionSee Channel Data Word Resolution table in Chapter 4
Module Update TimeDependent upon enabled channels (see Update Time, Chap 3)
Channel Turn-Off TimeUp to one module update time
Overall Accuracy
The accuracy of the module is determined by many aspects of the
hardware and software functionality of the module. The following
attempts to explain what the user can expect in terms of accuracy based
on the thermocouple, RTD, resistance, and millivolt, volt, and milliamp
inputs for the NI8u module.
76SLC 500™ Universal Analog Input Module
The accuracies specified as follows include errors due to the cold junction
compensation for thermocouples, current source errors for RTDs, and
hardware and software errors associated with the system, which depends
upon input path. RTD accuracies do not include errors due to lead
resistance. The hardware and software errors include calibration of the
system, and non-linearity of the ADC. For the sake of the calculations the
resolution of the ADC was assumed to be at least 16 bits (use of the
10Hz, 50Hz, and 60Hz filter frequencies). Note: The 250Hz frequency
should not be applied to thermocouple or RTD inputs if accuracy is a
concern.
Thermocouple
The following table provides the maximum error for each thermocouple
type when the 10Hz, 50Hz, or 60Hz filters are used and the module is
operating at 25°C and was calibrated at 25°C. Inaccuracies in the cold
junction compensation sensors are not included.
ThermocoupleMax. Error
Type25°C
J±0.6°C
K-225°C to 1370°C±1.0°C
K-270°C to -225°C±7.5°C
T-230°C to +400°C±1.0°C
T-270°C to -230°C±5.4°C
E-210°C to +1000°C±0.5°C
E-270°C to -210°C±4.2°C
R±1.7°C
S±1.7°C
B±3.0°C
N±0.4°C
C±1.8°C
The following table provides the maximum error for each thermocouple
type when the 10Hz, 50Hz, or 60Hz filters are used and the module is
operating at 0°C to 60°C and was calibrated at that temperature.
Inaccuracies in the cold junction compensation sensors are not included.
ThermocoupleMax. Error
Type0°C to 60°C
J±0.9°C
K-225°C to 1370°C±1.5°C
K-270°C to -225°C±10.0°C
T-230°C to +400°C±1.5°C
T-270°C to -230°C±7.0°C
E-210°C to +1000°C±0.8°C
E-270°C to -210°C±6.3°C
R±2.6°C
S±2.6°C
B±4.5°C
N±0.6°C
C±3.5°C
The diagrams that follow for each thermocouple type, give data for a
sample module over the input range of the thermocouple, over
temperature. Thermocouples are usually parabolic in their µV to degrees
C curves. Normally, at the ends of any given thermocouple range, the
ratio of change in temperature increases as a result of a change in voltage.
In other words, at the ends, a smaller change in voltage results in a larger
change in degrees.
0.1
0.05
0
-0.05
-0.1
-0.15
-0.2
Degrees C Deviation
-0.25
Appendix A: Module Specifications77
Thermocouple Type J, Exa mple Deviations
Ch 2 Delta, 25C
Ch 2 Delta, 0C
Ch 2 Delta, 60C
-0.3
-0.35
-210 -110 - 1090190290390490590690790
Degrees C TC Input
Thermocouple Type K, Example Deviations (Low Range )
3
2.5
2
1.5
1
0.5
Degrees C Deviation
0
-0.5
-270-260-250-240-230-220-210-200
Degrees C TC Input
Ch 2 Delta, 25C
Ch 2 Delta, 0C
Ch 2 Delta, 60C
78SLC 500™ Universal Analog Input Module
Thermocouple Type K, Example Deviations (High Range)
0.3
0.2
0.1
0
-0.1
Degrees C Deviation
-0.2
-0.3
-2000200400600800100012001400
Degrees C TC Input
Ch 2 Delta, 25C
Ch 2 Delta, 0C
Ch 2 Delta, 60C
Thermocouple Type T, Example Deviations (Low Range)
0.5
0
-0.5
-1
Degrees C Deviation
-1.5
-2
-270-260-250-240-230-220-210-200
Degrees C TC Input
Ch 2, Delta, 25 C
Ch 2 Delta, 0C
Ch 2 Delta, 60C
0.05
-0.05
Appendix A: Module Specifications79
Thermocouple Type T, Example Deviations (High Range)
The following table provides the maximum error for each RTD and
resistance type when the 10 Hz, 50 Hz, and 60 Hz filters are used and the
module is operating at 25°C and was calibrated at 25°C. Errors due to
lead wire resistance mismatches are not included.
10Ω Cu 426±3.0°C
120Ω Ni 618±0.4°C
120Ω Ni 672±0.4°C
3000Ω Resistance±2.0 Ω
Appendix A: Module Specifications83
The following table provides the maximum error for each RTD and
resistance type when the 10 Hz, 50 Hz, and 60 Hz filters are used and the
module is operating at 0°C to 60°C and was at that temperature. Errors
due to lead wire resistance mismatches are not included.