Control Technologies CTI 2557-A Operating instructions

CTI 2557-A SIXTEEN CHANNEL
ISOLATED RTD INPUT MODULE
INSTALLATION AND OPERATION GUIDE
Ver. 1.0
2557-AIOG 05 26 2021
$25

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CTI 2557-A Installation and Operation Guide
Copyright © 2021 Control Technology Inc.
All rights reserved.
This manual is published by Control Technology Inc., 5734 Middlebrook Pike, Knoxville, TN 37921.
This manual contains references to brand and product names which are tradenames, trademarks, and/or
registered trademarks of Control Technology Inc.2500 Series®, Siemens® and SIMATIC® are
registered trademarks of Siemens AG. Other references to brand and product names are tradenames,
trademarks, and/or registered trademarks of their respective holders.
DOCUMENT DISCLAIMER STATEMENT
Every effort has been made to ensure the accuracy of this document; however, errors do occasionally
occur. CTI provides this document on an "as is" basis and assumes no responsibility for direct or
consequential damages resulting from the use of this document. This document is provided without
express or implied warranty of any kind, including but not limited to the warranties of merchantability
or fitness for a particular purpose. This document and the products it references are subject to change
without notice. If you have a comment or discover an error, please call us toll-free at 1-800-537-8398.

CTI 2557-A Installation and Operation Guide
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PREFACE
This Installation and Operation Guide provides installation and operation instructions for the CTI
2557-A Sixteen Channel Isolated Thermocouple Input Module for CTI’s 2500 Series 2500®
Processors as well as the legacy SIMATIC® 505 programmable controllers. We assume you are
familiar with the operation of CTI’s 2500 Series 2500® Processors and SIMATIC® Series 505
programmable controllers. Refer to the appropriate CTI’s Series 2500® documentation for Processors
and I/O module operation.
This Installation and Operation Guide is organized as follows:
Chapter 1 provides a description of the module.
Chapter 2 covers installation and wiring.
Chapter 3 is a guide to troubleshooting.
Figure 1 The 2557-A 16 Channel RTD Input Module

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CTI 2557-A Installation and Operation Guide
TABLE OF CONTENTS
PREFACE ...............................................................................................................................................iii
TABLE OF CONTENTS........................................................................................................................ iv
TABLE OF FIGURES ............................................................................................................................ vi
USAGE CONVENTIONS ...................................................................................................................... ix
CHAPTER 1. DESCRIPTION..................................................................................................................1
1.1 Asynchronous Operation........................................................................................2
1.1.1 Compatibility with Immediate I/O .........................................................................2
1.2 100 Ohm, 10 Ohm, 120 Ohm RTDs, or Millivolt Inputs ......................................2
1.3 Digital Word Map..................................................................................................2
1.4 RTD Input to Digital Conversion...........................................................................2
1.4.1 Engineering Units...................................................................................................3
1.4.2 Scale Units..............................................................................................................3
1.5 Effect of Out-of-Range Input Signals....................................................................4
1.6 Resolution ..............................................................................................................5
CHAPTER 2. INSTALLATION...............................................................................................................6
2.1 Planning the Installation.........................................................................................6
2.2 Calculating the I/O Base Power Budget.................................................................6
2.3 Unpacking the Module...........................................................................................6
2.4 Configuring the Module.........................................................................................7
2.4.1 Selecting Temperature or Millivolt Input ..............................................................7
2.4.2 Selecting 2 and 3 Wire or 4 Wire Operation..........................................................8
2.4.3 Selecting 10 Ohm RTD Inputs...............................................................................8
2.4.4 Selecting PLC Login Mode....................................................................................8
2.4.5 Selecting Digital Filtering......................................................................................8
2.4.6 Select Degrees Celsius or Fahrenheit.....................................................................8
2.4.7 Selecting Data Scaling ...........................................................................................9
2.5 Inserting the Module Into the I/O Base................................................................11
2.6 Wiring the Input Connectors................................................................................12
2.6.1 Connecting the Shield Wiring..............................................................................15
2.7 Checking Module Operation................................................................................16
CHAPTER 3. TROUBLESHOOTING...................................................................................................18
SPECIFICATIONS .................................................................................................................................19
Specifications subject to change without notice.........................................................................20
JUMPER SETTINGS LOG SHEET.......................................................................................................21
USER NOTES.........................................................................................................................................22

CTI 2557-A Installation and Operation Guide
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LIMITED PRODUCT WARRANTY.....................................................................................................23
THE WARRANTY SET FORTH ABOVE IN THIS ARTICLE IS THE ONLY WARRANTY
CTI GRANTS AND IT IS IN LIEU OF ANY OTHER IMPLIED OR EXPRESSED
GUARANTY OR WARRANTY ON CTI PRODUCTS, INCLUDING WITHOUT
LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR OF FITNESS FOR A
PARTICULAR PURPOSE AND IS IN LIEU OF ALL OBLIGATIONS OR LIABILITY
OF CTI FOR DAMAGES IN CONNECTION WITH LOSS, DELIVERY, USE OR
PERFORMANCE OF CTI PRODUCTS OR INTERRUPTION OF BUSINESS, LOSS OF
USE, REVENUE OR PROFIT. IN NO EVENT WILL CTI BE LIABLE FOR SPECIAL,
INCIDENTAL, OR CONSEQUENTIAL DAMAGES.......................................................23
REPAIR POLICY ...................................................................................................................................24

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CTI 2557-A Installation and Operation Guide
TABLE OF FIGURES
Figure 1 The 2557-A 16 Channel RTD Input Module..............................................................................iii
Figure 2 2557-A Module Front View............................................................................................................1
Figure 3 Word Input to the PLC from the Module......................................................................................2
Figure 4 Example Change Input Level........................................................................................................3
Figure 5 Effect of Voltage Input - 100 Ohm Platinum......................................................................................4
Figure 6 Effect of Voltae Input - 120 Ohm Nickel.......................................................................................4
Figure 7 Effect of Voltage Input - 10 Ohm Copper ....................................................................................5
Figure 8 Effect of Voltage Input - Millivolts..................................................................................................5
Figure 9 Input Resolution...............................................................................................................................5
Figure 10 Factory Configuration Jumper Settings.....................................................................................9
Figure 11 Configuration Jumper Locations...............................................................................................10
Figure 12 2557-A Module PCB Layout......................................................................................................11
Figure 13 Copper Wire Table at 25 Degrees Celsius..............................................................................12
Figure 14 Removable Wiring Connector Wiring Diagram.......................................................................13
Figure 15 Wiring Diagram for 2, 3 , 4 Wire RTDs and Millivolt Signals................................................14
Figure 16 Cable Grounding.........................................................................................................................16
Figure 17 Example I/O Configuration Chart..............................................................................................17
Figure 18 Troubleshooting Matrix...............................................................................................................18

CTI 2557-A Installation and Operation Guide
ix
USAGE CONVENTIONS
NOTE:
Notes alert the user to special features or procedures.
CAUTION:
Cautions alert the user to procedures which could damage equipment.
WARNING:
Warnings alert the user to procedures which could damage equipment and endanger the user.

CTI 2557-A Installation and Operation Guide
1
CHAPTER 1. DESCRIPTION
This Installation and Operation Guide provides installation and operation instructions for the
CTI 2557-A 8-Channel Analog Output Module for SIMATIC® 505 and CTI 2500 Series® programmable
controllers. We assume you are familiar with the operation of the CTI 2500 Series® programmable
controllers. Refer to the appropriate user documentation for specific information on the CTI 2500 Series®
programmable controllers and I/O modules.
The Model 2557-A is designed to translate 10 Ohm copper, 100 Ohm platinum and, 120 Ohm nickel RTDs
or millivolt input signals into scaled digital words which are then sent to the programmable controller (PLC).
The 2557-A RTD Input Module features built-in independenttwo, three,or four lead compensationforeach
RTD input. The 2557-A uses 8 8 point removable wiring connectors. The connectors are provided with
the module. Support for other RTD types is available through special request from the factory. Call CTI at
1-800-537-8398 to determine if support is available for your special RTD type.
Figure 2 2557-A Module Front View

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CTI 2557-A Installation and Operation Guide
1.1 Asynchronous Operation
The module operates asynchronously with respect to the PLC; a scan of the PLC and input sampling of
the module do not occur at the same time. Instead, the module will translate all inputs in one module
update (20 milliseconds maximum) and store the translated words in a buffer memory. The PLC
retrieves the stored words from the module buffer memory at the start of the I/O scan.
1.1.1 Compatibility with Immediate I/O
The Model 2557-A has been tested and is compatible with the Immediateread function of the
SIMATIC® 545 and 555 PLC.
1.2 100 Ohm, 10 Ohm, 120 Ohm RTDs, or Millivolt Inputs
Each of the module's 16 channels may be configured to receive either a 100 Ohm platinum RTD or a
120 Ohm nickel RTD or a 10 Ohm copper RTD input signal (two, three or four wire) or a DC
voltage signal ranging from 0 to 100 millivolts. Selection of 10 Ohm, 100 Ohm or 120 Ohm RTDs or
millivolts are made via internal switch and jumper settings.
1.3 Digital Word Map
RTD and/or millivolt signals are translated into a 14-bit digital word. Since the PLC requires a 16-bit
input word, the 14-bit value from the converter is placed into a 16-bit word for transmittal to the PLC.
As shown in the following figure, of the two bits not used for the digital word, one is used to show the
sign of the word, while the other is used to note values which are "overrange or underrange."
1.4 RTD Input to Digital Conversion
Figure 3 Word Input to the PLC from the Module

CTI 2557-A Installation and Operation Guide
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1.4.1 Engineering Units
The following equations may be used to calculate the digital word in decimal format which will result
from a particular RTD input:
RTD Mode, Digital Word (WX) = Degrees X 10
Millivolt Mode, Digital Word (WX) = Millivolts X 100
As an example, the following figure illustrates the effects of a change in input level going from 0 to
102.4 degrees in the RTD Input Mode.
Figure 4 Example Change Input Level
1.4.2 Scale Units
When data format is selected as SCALE the full temperature range of the RTD is scaled as an
unsigned integer from 0-32000. The following formula may be used to calculate the scaled integer
value:
Scaled Integer = (measured temp - min temp) ÷ (max temp - min temp) × 32000
For example the scaled integer offset at 0'C for a 1000 Pt RTD is:
Scaled Integer = 0 - (-199.8) ÷ (849 - (-199.8)) × 32000 = 6091

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CTI 2557-A Installation and Operation Guide
1.5 Effect of Out-of-Range Input Signals
RTD inputs exceeding 849.8 degrees C for 100 Ohm platinum or 260.0 degrees C for 120 Ohm nickel
and 10 Ohm copper will cause the overrange bit to be set. A maximum temperature of 849.9 degrees
C for 100 Ohm platinum or 260.1 degrees C for 120 Ohm nickel and 10 Ohm copper will be returned
for any positive overrange input.
Similarly an input below -199.8 degrees C for 100 Ohm platinum or -79.8 degrees C for 120 Ohm
nickel or -100 degrees C for 10 Ohm copper will cause the underrange bit to be set.
Figure 5 Effect of Voltage Input - 100 Ohm Platinum
Figure 6 Effect of Voltae Input - 120 Ohm Nickel
NOTE:
The Model 2557-A uses the least significant bit (16) to indicate an open RTD. The
value of this bit is set to 1 when this condition occurs.

CTI 2557-A Installation and Operation Guide
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Figure 7 Effect of Voltage Input - 10 Ohm Copper
Figure 8 Effect of Voltage Input - Millivolts
Millivolt inputs exceeding 103.04 millivolts will cause the overrange bit to be set. A reading of 103.05
millivolts will be returned for any positive over-range input.
Similarly, a millivoltinput below 0 millivolts will cause the under-range bit to be set. A reading of 1
millivolt will be returned for any negative under-range input.
1.6 Resolution
The module has a resolution of approximately 0.1 degrees C, 0.2 degrees F or exactly 0.01 millivolts.
The chart below shows the corresponding input resolution per step for each of the input configuration
modes:
Figure 9 Input Resolution

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CTI 2557-A Installation and Operation Guide
CHAPTER 2. INSTALLATION
The installation of the 2557-A Sixteen Channel RTD Input Module involves the following steps:
1. Planning theinstallation
2. Configuring the module
3. Inserting the module into the I/O base
4. Wiring the module input connector
5. Checking module operation
The steps listed above are explained in detail in the following pages.
2.1 Planning the Installation
Planning is the first step in the installation of the module. This involves calculating the I/O base power
budget and routing the input signal wiring to minimizenoise. The following sections discuss these
important considerations.
2.2 Calculating the I/O Base Power Budget
The Model 2557-A requires 5 watts of +5 VDC power from the I/O base. Use this figure to verify that
the base power supply capacity is not exceeded.
2.3 Unpacking the Module
Open the shipping carton and remove the special anti-static bag which contains the module.
After discharging any static build-up, remove the module from the static bag. Do not discard the static
bag. You will need it for the following configuration procedure.
CAUTION:
HANDLING STATIC SENSITIVE DEVICES
The components on the 2557-A module printed circuit card can be damaged by static electricity
discharge. To prevent this damage, the module is shipped in a special anti-static bag. Take the
following precautions before removing the module from the bag, when opening the module, and
when handling the printed circuit card during configuration.
Discharge any static potential by holding the module in its anti-static bag and touch the metal
chassis of the PLC. During the configuration step, hold the printed circuit card only by its
edges. Do not touch the circuit card pin connectors, or solder connections.

CTI 2557-A Installation and Operation Guide
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2.4 Configuring the Module
The Model 2557-A must be configured for 10 Ohm copper, 100 Ohm platinum or 120 Ohm nickel
RTDs (2, 3 or 4 wire) or millivolt range and digital filtering/no filtering mode before wiring the input
connectors and inserting the module into the I/O base.
Configuring the module is a two step process. Hardware jumpers are positioned to provide proper gain
and lead wire compensation for either 3 wire or 4 wire RTDs. DIP switches are provided to inform the
microprocessor the changes made to the hardware.
Changing the module input channel configuration involves the following steps:
1. Selecting temperature or millivolt measurement via DIP switch
2. Selecting 3 or 4 wire compensation
3. Selecting 100 Ohm platinum, 120 Ohm nickel or 10 Ohm copper input mode for each channel
4. Selecting standard login mode (16WX) or Advanced Operating Mode
5. Selecting digital filtering or no filtering for the module
6. Selecting degrees C or F for the module
7. Selecting Engr units or SCALE units for module
8. Logging the configuration jumper settings for future reference
Each of these steps is described in the following sections.
2.4.1 Selecting Temperature or Millivolt Input
No hardware changes are required for millivolt inputs. To select millivolt input mode for an input turn
OFF the M and L switch for the input channel. (See Figure 10.) To select a particular RTD probe for
each channel configure the M and L switch.
M
L
0
0
Millivolt
0
1
100 Cu
1
0
1000 Pt
1
1
1200 Ni
NOTE:
Each channel contains a jumper to select between 2, 3 and 4 wire RTD elements. (See Figure
10, JP68). For 2 wire and 3 wire RTDs no change is required. For 4 wire RTDs the jumper
should be removed and placed on a single pin for storage.
NOTE:
As shipped, all input channels are configured 100 Ohm platinum, 3 wire RTDs, degrees
Centigrade and digital filtering enabled.

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CTI 2557-A Installation and Operation Guide
or 120 RTD.
2.4.2 Selecting 2 and 3 Wire or 4 Wire Operation
As shipped the module is ready to accept 2 and 3 wire RTDs. To configure an input channel for 4 wire
operation requires the following steps:
1. Remove the 3 wire select jumper JP68-JP83 for the appropriate input channel and store on
a single pin.
2. Move 2 input jumpers/channel to the 4 wire position. For example: To configure
Channel 1 move JP1 and JP2 to the 4 wire position. (See Figure 10.)
2.4.3 Selecting 10 Ohm RTD Inputs
If a 10 Ohm RTD is selected the gain of the input amplifier must be increased to process the smaller
signal levels. (See Figure 10.) JP49-JP64 are the amplifier gain select jumpers for Channels 1-16. No
0 0
jumper changes are required to select 100
2.4.4 Selecting PLC Login Mode
Locate JP67 on the printed circuit board to select PLC Login Mode (See Figure 10). Standard login is
16 WX registers in the PLC. Advanced Operating Mode logs in as 16 X, 16 Y, 32 WX and 32 WY
registers. Consult the CTI 255x Sixteen Channel Advanced Function Programming Reference Manual
part #62-177, if the advanced operating mode is to be selected.
2.4.5 Selecting Digital Filtering
Locate the Digital Filtering Jumper JP65 (see Figures 9 and 10). To enable digital filtering, set the
jumper in the ENABLED position. Since many analog input signals contain noise,CTI recommends
using digital filtering unless maximum response time is required.
2.4.6 Select Degrees Celsius or Fahrenheit
Locate the temperature scaling jumper JP66 on the righthand side of the module (see Figure 10) and
select either degrees Fahrenheit or Celsius by positioning the jumper in the DEG F or DEG C position.

CTI 2557-A Installation and Operation Guide
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2.4.7 Selecting Data Scaling
Locate JP90 on the printed circuit board (See Figure 10). Select DISABLE to present data to the PLC
as temperature X10 or millivolts X100. Select ENABLE to scale and present the data as an unsigned
integer from 0-32000.
Figure 10 Factory Configuration Jumper Settings
NOTE:
In the sample chart above the standard shipping configuration is indicated as 3 wire 100
0.
Pt,
16 WX, filtering enabled, degrees C and scaling disabled.

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CTI 2557-A Installation and Operation Guide
Figure 11 Configuration Jumper Locations

CTI 2557-A Installation and Operation Guide
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Figure 12 2557-A Module PCB Layout
2.5 Inserting the Module Into the I/O Base
Insert the module into the I/O base by carefully pushing the module into the slot. When the module is
fully seated in the slot, tighten the captive screws at the top and bottom to hold the module in place. To
remove the module from the I/O base, loosen the captive screws, then remove the module from the I/O
base. Be careful not to damage the connector card at the back of the module when inserting or
removing the module.
WARNING:
Remove power from the I/O base before inserting or removing a module.
Removable Wiring
Connectors
Channel Measurement
Selection DIP Switches
2,3 and 4 Wire RTD Selection Jumpers
per Channel
Scaling, Filtering, Degrees C
or F and Advanced Features
Jumper Selection

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CTI 2557-A Installation and Operation Guide
2.6 Wiring the Input Connectors
RTD input signals are accepted through a 64 position fixed connector with wire press in terminals
located on the front of the module. Consult the RTD manufacturer's recommendations for selecting the
input wire type and size. The connector will accept 18 to 30 AWG wire.
The Model 2557-A uses a fixed connector to terminate field wiring. This is used because the chemistry
of a removable connector may have an adverse effect on the accuracy of the measurement. CTI has
carefully selected a connector that minimizes this effect.
Refer to Figure 13 for correct wiring for 2, 3, or 4 wire RTDs to the Model 2557-A. Each channel
consists of four press in terminals. Insert wire by using a small screw driver to depress the spring
tension leverand then insert the wire. Solid core wires may be pushed in without depressing lever.
Remove wire by depressing spring lever to remove tension and then remove lead wire. (See Figure 12)
The Model 2557-A may compensate for up to 20 Ohm of lead resistance per wire. Use the table in
Figure 9 in planning the maximum distance the RTD may be located from the module.
Figure 13 Copper Wire Table at 25 Degrees Celsius