Control Technologies 2556-A Operating instructions

CTI 2556-A SIXTEEN CHANNEL
ISOLATED THERMOCOUPLE INPUT MODULE
INSTALLATION AND OPERATION GUIDE
Version 1.0
$25

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CTI 2556 Installation and Operation Guide
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Copyright © 2020 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. 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 orconsequential
damages resulting from the use of this document. This document is provided without express or implied
warranty of any kind, including but not limitedto the warranties of merchantiblility or fitness for a particular
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comment or discover an error, please call us toll-free at 1-800-537-8398.
REVISION HISTORY
Version 1.0
6/1/20
Original Release

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CTI 2556 Installation and Operation Guide
2
PREFACE
This Installation and Operation Guide provides installation and operation instructions for the CTI 2556-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 2556-A 16-Channel Isolated Thermocouple Input Module

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CTI 2556 Installation and Operation Guide
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.

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CTI 2556 Installation and Operation Guide
TABLE OF CONTENTS
Contents
REVISION HISTORY..............................................................................................................................................i
CHAPTER 1. DESCRIPTION...................................................................................................................................1
1.1 Front Panel Description ....................................................................................................................1
1.1.1 Active LED.......................................................................................................................2
1.1.2 Input Terminals for Channels 1-16...................................................................................2
1.2 Asynchronous Operation ..................................................................................................................2
1.2.1 Immediate I/O Compatibility.........................................................................................................2
1.3 J, K, R, S, T, E, or L Thermocouples and mV .................................................................................2
1.4 Digital Word Map.............................................................................................................................2
1.5 Thermocouple Input to Digital Conversion......................................................................................3
1.5.1 Engineering Units.............................................................................................................3
1.5.2 Scale Units........................................................................................................................3
1.6 Effect of Out-of-Range Input Signals...............................................................................................3
1.7 Resolution.........................................................................................................................................6
CHAPTER 2. INSTALLATION................................................................................................................................7
2.1 Planning the Installation ...................................................................................................................7
2.2 Calculating the I/O Base Power Budget ...........................................................................................7
2.3 Unpacking the Module......................................................................................................................7
2.4 Configuring the Module....................................................................................................................8
2.4.1 Selecting Thermocouple or Millivolt Measurement via DIP Switch ...............................8
2.4.2 Selecting Thermocouple Type Input via Hardware Jumpers............................................9
2.4.3 Selecting PLC Login Mode..............................................................................................9
2.4.4 Selecting Data Format ......................................................................................................9
2.4.5 Selecting Digital Filtering.................................................................................................9
2.4.6 Select Degrees Celsius or Fahrenheit.............................................................................10
2.5 Inserting the Module Into the I/O Base ..........................................................................................12
2.6 Wiring the Input Connectors...........................................................................................................13
2.6.1 Connecting the Shield Wiring......................................................................................................15
2.7 Checking Module Operation...........................................................................................................16
CHAPTER 3. TROUBLESHOOTING....................................................................................................................18
SPECIFICATIONS ..................................................................................................................................................19
JUMPER SETTINGS LOG SHEET ........................................................................................................................21
THERMOCOUPLE WIRE GUIDE.........................................................................................................................22
LIMITED PRODUCT WARRANTY......................................................................................................................24
REPAIR POLICY.....................................................................................................................................................25

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CTI 2556 Installation and Operation Guide
TABLE OF FIGURES
Figure 1 2556-A 16-Channel Isolated Thermocouple Input Module ...........................................................ii
Figure 2 2556-A Front Panel Description...........................................................................................................1
Figure 3 Word Input to the PLC from the Module............................................................................................2
Figure 4 Example Change in Input Level...........................................................................................................3
Figure 5 Effect of Voltage Input on Type J Thermocouple...........................................................................4
Figure 6 Effect of Voltage Input on Type K Thermocouple ..........................................................................4
Figure 7 Effect of Voltage Input on Type R Thermocouple ..........................................................................4
Figure 8 Effect of Voltage Input on Type S Thermocouple...........................................................................4
Figure 9 Effect of Voltage Input on Type T Thermocouple...........................................................................5
Figure 10 Effect of Voltage Input on Type E Thermocouple ........................................................................5
Figure 11 Effect of Voltage Input on Type L Thermocouple.........................................................................5
Figure 12 Effect of Voltage Input on Millivolt Range......................................................................................5
Figure 13 Input Resolution....................................................................................................................................6
Figure 14 Factory Configuration Jumper Settings .......................................................................................10
Figure 15 Printed Circuit Board Layout...........................................................................................................11
Figure 16 Configuration Jumper Location......................................................................................................12
Figure 17 Input Connector Wiring.....................................................................................................................13
Figure 18 Thermocouple Wiring Application..................................................................................................14
Figure 19 Millivolt Wiring Application..............................................................................................................14
Figure 20 Example I/O Configuration Chart....................................................................................................16
Figure 21 Troubleshooting Matrix.....................................................................................................................18

1 2556-A Installation & Operation Guide
CHAPTER 1. DESCRIPTION
The Sixteen Channel Thermocouple Input Module is a member of Control Technology's family of I/O modules
compatible with the all 2500 Series 2500® Processors and the SIMATIC® 505 Series programmable
controllers. The Model 2556-A is designed to translate a J, K, R, S, T, E, and L (DIN J) thermocouple or
millivolt input signal into an equivalent digital word which is then sent to the programmable controller (PLC).
The 2556-A Thermocouple Input Module features built-in independent internal cold junction
compensation and linearization for each thermocouple input for Types J, K, E, R, S, L, and T. No
external cold junction compensation is required.
1.1 Front Panel Description
Figure 2 2556-A Front Panel Description
ACTIVE LED
2559-FPC 40 Pin Removable Connector
Note: This connector is required and
is ordered separately

2 2556-A Installation & Operation Guide
1.1.1 Active LED
The Active LED will be illuminated when the module is functioning normally. If the Active LED is not lit,
refer to Chapter 3 for troubleshooting.
1.1.2 Input Terminals for Channels 1-16
The Model 2556-A uses CTI’s 2559-FPC with Cold Junction Compensation built into the connector. This
connector provides wiring terminals for channels 1-16 and is ordered separately.
1.2 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 (24
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.
1.2.1 Immediate I/O Compatibility
The Model 2556-A has been tested and is compatible with the Immediate Read function of the SIMATIC®
545 and 555 PLC. The Model 2556-A is compatible with 545 and 555 PLCs. It is compatible with the 525
PLCs in 16WX mode only.
1.3 J, K, R, S, T, E, or L Thermocouples and mV
Each of the module's sixteen channels may be configured to receive either J, K, R, S, T, E, or L thermocouple
input signals or a DC voltage signal ranging from -55 to +55 millivolts. Selection of thermocouple type or
millivolts are made via internal DIP switch settings and hardware jumpers (see Sections 2.4.1 and 2.4.2).
1.4 Digital Word Map
Thermocouple 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."
Figure 3 Word Input to the PLC from the Module

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1.5 Thermocouple Input to Digital Conversion
1.5.1 Engineering Units
The following equations may be used to calculate the digital word in decimal format which will result from a
particular thermocouple input:
Thermocouple Mode, Digital Word (WX) = Degrees X10
Millivolt Mode, Digital Word (WX) = Millivolts X100
As an example, the following figure illustrates the effects of a change in input level going from 0° to
102.4°F in the Thermocouple Input Mode.
Figure 4 Example Change in Input Level
1.5.2 Scale Units
When data format is selected as SCALE the full temperature range of the thermocouple 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) x 32000
Scaled Integer = (mV –(-50)) ÷ (50 –(-50)) x 32000 = (mV + 55) ÷ 100 x 32000
For example the scaled integer offset at 0°C for a Type J thermocouple is:
Scaled integer = 0 - (-210) ÷ (760 - (-210)) x 32000 = 6928
For mV mode, the scaled integer at 0mV is:
Scaled integer = (0mV + 50) ÷ 100 x 32000 = 16000
1.6 Effect of Out-of-Range Input Signals
Thermocouple inputs exceeding the ANSI standard of 760 degrees C for Type J, or 1768 degrees C for Type
R and S, and 1000 degrees C for Type E will cause the overrange bit to be set and the maximum temperature
for that thermocouple type to be returned. Open thermocouples report temperatures that are out of the
allowable range. This condition may occur due to failure of the thermocouple or due to the thermocouple wire
being cut or disconnected. The Model 2556-A will report an open thermocouple condition within 200
milliseconds.
For mVsignals in SCALE mode (0-32000), the module will report >32000 if the input voltage > 50mV and will
reach a maximum reported value of 32767 at approximately +52.5mV. For negative inputs <-50mV, the module
will report negative values (<0) and will reach a minimum reported value of -2115 at about -56.5mV.

4 2556-A Installation & Operation Guide
Figure 5 Effect of Voltage Input on Type J Thermocouple
Figure 6 Effect of Voltage Input on Type K Thermocouple
Figure 7 Effect of Voltage Input on Type R Thermocouple
Figure 8 Effect of Voltage Input on Type S Thermocouple
NOTE:
The Model 2556-A uses the least significant bit (16) to indicate an open thermocouple. The
value of this bit is set to 1 when this condition occurs. An open thermocouple condition will
report within 200 milliseconds.

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Figure 9 Effect of Voltage Input on Type T Thermocouple
Figure 10 Effect of Voltage Input on Type E Thermocouple
Figure 11 Effect of Voltage Input on Type L Thermocouple
Figure 12 Effect of Voltage Input on Millivolt Range

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1.7 Resolution
The module has a resolution of approximately 0.1°C, 0.2°F or 0.01 millivolts.
The chart below shows the corresponding input resolution per step for each of the input configuration modes:
Figure 13 Input Resolution

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CHAPTER 2. INSTALLATION
The installation of the 2556-A Sixteen Channel Thermocouple 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 minimize noise. The following sections discuss these important
considerations.
2.2 Calculating the I/O Base Power Budget
The Model 2556-A requires 5 watts of +5 VDC power from the I/O base. Use these values 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 2556-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.

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2.4 Configuring the Module
The Model 2556-A must be configured for type J, K, R, S, T, E thermocouples or millivolt range and digital
filtering/no filtering mode before wiring the input connectors and inserting the module into the I/O base.
Changing the module input channel configuration involves the following steps:
1. Selecting thermocouple type or millivolt measurement via DIP switch
2. Selecting thermocouple type or millivolt input for each channel via hardware jumpers
3. Selecting digital filtering or no filtering for the module
4. Selecting standard login mode (16WX) or Advanced Operating Mode
5. Selecting degrees Celsius or Fahrenheit
6. Selecting Engr units or SCALE units for module
7. Logging the configuration jumper settings for future reference
Each of these steps is described in the following sections.
2.4.1 Selecting Thermocouple or Millivolt Measurement via DIP Switch
DIP switches 1-4 on the inside edge of the printed circuit board are used to inform the microcomputer of
changes in setup in the hardware selection jumpers (see Figure 16 Configuration Jumper Location). Each
channel has 3 switches to represent the thermocouple type or millivolt measurement that is performed.
Switch Position
BCD Value
Measurement Selected
OFF OFF OFF
0
Millivolt
OFF OFF ON
1
E
OFF ON OFF
2
J
OFF ON ON
3
K
ON OFF OFF
4
L
ON OFF ON
5
R
ON ON OFF
6
S
ON ON ON
7
T
NOTE:
As shipped, all input channels are configured for Type J thermocouples (degrees Celsius) and
digital filtering enabled, 16 WX mode and engineering units.
NOTE:
The ON position is selected by pushing the switch toward the center of the printed circuit
board.

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2.4.2 Selecting Thermocouple Type Input via Hardware Jumpers
Locate the hardware Thermocouple Compensation Jumpers corresponding to input channels 1 through
16. These jumpers are located adjacent to the input terminal strip (see Figure 16 Configuration Jumper
Location). For each input channel, select either millivolt input or thermocouple type by placing the jumper in
the correct position.
2.4.3 Selecting PLC Login Mode
Locate JP68 on the printed circuit board to select PLC Login Mode (Figure 16 Configuration Jumper
Location). Standard login is 16WX registers in the PLC. Advanced Operating Mode logs in as 16X, 16Y,
32WX and 32WY registers. Consult the CTI 255x Sixteen Channel Advanced Function Programming
Reference Manual, part #62-177, if the advanced operating mode is to be selected.
2.4.4 Selecting Data Format
Locate SCALE jumper JP69 on the printed circuit board (Figure 16 Configuration Jumper Location).
Select Engr to present data to the PLC as temperature X10 or Millivolt X100. Select SCALE to scale and
present data as an unsigned integer from 0-32000.
2.4.5 Selecting Digital Filtering
Locate the Digital Filtering Jumper JP67 (Figure 16 Configuration Jumper Location). 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. Digital filtering applies to
both thermocouple or millivolt inputs.
The time step for digital filtering is .080 seconds. The filtering technique used provides that the full range of a
voltage change reported to the PLC will be accomplished in 5 time steps or .40 seconds. The voltage change
will be reported as a continuous exponential function over this time period with values at each time step as
indicated at .08 seconds, the value is 63% of full range at .16 seconds, the value is 86% of full range
at .24 seconds, the value is 95% of full range, and at .40 seconds, the value is 99% of full range.
NOTE:
Engineering Data Format must be selected for millivolt mode.

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2.4.6 Select Degrees Celsius or Fahrenheit
Locate the temperature scaling jumper JP66 on the right hand side of the module (see Figure 16
Configuration Jumper Location) and select either degrees Celsius or Fahrenheit by positioning the jumper in
the "DEG C" or "DEG F" position.
Figure 14 Factory Configuration Jumper Settings

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Figure 15 Printed Circuit Board Layout

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Figure 16 Configuration Jumper Location
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.

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2.6 Wiring the Input Connectors
Thermocouple input signals are accepted through a removable connector the 2559-FPC plugged into the front
of the module. Consult the thermocouple manufacturer's recommendations for selecting the input wire type and
size. The front connector accepts wire from 14 to 22 AWG.
To assign an input to a specific channel, locate the appropriate channel position on the connector as shown in
the following figure. Wires must be inserted by pressing the wire into the connector receptacle and tightening
the cage clamp screw. To remove the wire unscrew the cage clamp screw then remove the thermocouple wire.
Figure 17 Input Connector Wiring

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Figure 18 Thermocouple Wiring Application
Figure 19 Millivolt Wiring Application