Control Technologies CTI 2451 Operating instructions

CTI 2451 EIGHT CHANNEL
THERMOCOUPLE INPUT MODULE
INSTALLATION AND OPERATION GUIDE
Version 1.2
CTI Part #062-00111
2451IOG 051403 $25

ii CTI 2451 Installation and Operation Guide
Copyright © 2003 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 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 merchantiblility 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 2451 Installation and Operation Guide iii
Figure 1 The Model 2451 Thermocouple Input Module
PREFACE
This Installation and Operation Guide provides installation and operation instructions for the CTI 2451
Eight Channel Thermocouple Input Module for SIMATIC® 405 programmable controllers. We assume
you are familiar with the operation of SIMATIC® 405 Series programmable controllers. Refer to the
appropriate SIMATIC® user documentation for specific information on the SIMATIC® 405
programmable controllers and I/O modules.
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.

iv CTI 2451 Installation and Operation Guide

CTI 2451 Installation and Operation Guide v
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.
USAGE CONVENTIONS

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CTI 2451 Installation and Operation Guide vii
TABLE OF CONTENTS
PREFACE ..........................................................................iii
USAGE CONVENTIONS ............................................................ v
TABLE OF FIGURES ................................................................ ix
CHAPTER 1. DESCRIPTION ......................................................... 1
1.1 Asynchronous Operation .................................................... 1
1.1.1 Active Channels .................................................. 1
1.2 Type "J" or Type "K" Thermocouple .......................................... 2
1.3 Digital Word Map ......................................................... 2
1.4 Thermocouple Input to Digital Conversion ...................................... 3
1.5 Effect of Out-of Range Input Signals .......................................... 3
1.6 Resolution ............................................................... 4
CHAPTER 2. INSTALLATION ....................................................... 5
2.1 Planning the Installation .................................................... 5
2.2 Calculating the I/O Base Power Budget ........................................ 5
2.3 Unpacking the Module ..................................................... 5
2.4 Configuring the Module ..................................................... 6
2.4.1 Select Millivolt or Temperature Input .................................. 7
2.4.2 Selecting Type "J" or Type "K" Thermocouple Inputs ..................... 7
2.4.3 Selecting Digital Filtering ........................................... 7
2.4.4 Select Degrees Fahrenheit or Celsius .................................. 8
2.5 Inserting the Module into the I/O Base ......................................... 8
2.6 Wiring the Input Connectors ................................................. 8
2.6.1 Wiring Guidelines ................................................. 9
2.6.2 Wiring Examples .................................................. 10
2.7 I/O Configuration and Input Format ........................................... 12
2.7.1 Octal Numbering .................................................. 12
2.7.2 Input Format ..................................................... 12
2.7.3 Operating the Module .............................................. 13
2.8 Decoding Channels ........................................................ 14
2.9 Checking Module Operation ................................................. 15
CHAPTER 3. TROUBLESHOOTING .................................................. 17
SPECIFICATIONS .................................................................. 19
LIMITED PRODUCT WARRANTY ................................................... 23
REPAIR POLICY ................................................................... 25

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CTI 2451 Installation and Operation Guide ix
TABLE OF FIGURES
Figure 1 The Model 2451 Thermocouple Input Module ......................................iii
Figure 2 Active Channels ............................................................. 1
Figure 3 Word Map ................................................................. 2
Figure 4 Example Change in Input Level ................................................ 3
Figure 5 Effect of Temperature Input on Module Performance ............................... 3
Figure 6 Effect of Voltage Input on Module Performance ................................... 4
Figure 7 Input Resolution ............................................................ 4
Figure 8 Jumper Locations ........................................................... 6
Figure 9 Factory Configuration Jumper Settings .......................................... 7
Figure 10 Screw Terminal Block Wiring ................................................. 8
Figure 11 Thermocouple Wiring Example ................................................ 10
Figure 12 Millivolt Wiring Example .................................................... 11
Figure 13 Unused Bits ............................................................... 12
Figure 14 Active Channel Bits ......................................................... 12
Figure 15 Data Word ................................................................ 13
Figure 16 Example Measurement ...................................................... 13
Figure 17 Ladder Diagram Example .................................................... 14

xCTI 2451 Installation and Operation Guide

CTI 2451 Installation and Operation Guide 1
Figure 2 Active Channels
CHAPTER 1. DESCRIPTION
The Model 2451 Eight Channel Thermocouple Input Module is a member of Control Technology's family
of I/O modules compatible with the SIMATIC® 405 Series programmable controllers. The Model 2451
is designed to translate Type "J" thermocouples, Type "K" thermocouples and millivolt input signals into
equivalent digital words which are then sent to the programmable controller (PLC).
The Model 2451 Thermocouple Input Module features built-in cold junction compensation for each
thermocouple input. Support for other thermocouple 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 thermocouple
type.
1.1 Asynchronous Operation
The module operates asynchronously with the CPU. That is, the update times of the CPU and module do
not occur simultaneously. The module converts all selected thermocouple inputs in one module update
(which is less than 3.0 milliseconds per selected channel), and stores the digital information in a buffer.
1.1.1 Active Channels
One of the channels is considered to be active during each CPU scan. On any given CPU scan, both an
indicator describing which channel is active and the information for the active channel is transferred
from the module to the CPU. Following the transfer, the channel is deactivated and the next selected
channel automatically becomes active. The next CPU scan triggers the active channel indicator and data
for this channel and sends it to the CPU; this process repeats. Eight CPU scans are required to obtain
data from all eight channels. Thus, although the module itself performs conversion asynchronously with
the CPU, the transmission of data from the module to the CPU is asynchronous with the CPU scan. This
process is illustrated in the following figure.

2CTI 2451 Installation and Operation Guide
Figure 3 Word Map
The module appears to the controller as 32 X inputs. The module can be installed in any slot of any
Series 405 base. Since the Series 405 CPU supports 320 total X inputs, a maximum of 10 thermocouple
input modules (80 channels) can be installed in a single Series 405 system.
1.2 Type "J" or Type "K" Thermocouple
Each of the module's eight channels may be configured to receive either a Type "J" Thermocouple or a
Type "K" non-grounded thermocouple input signal. The module may also be configured to receive DC
voltage signals ranging from 0 to 55 millivolts. Selection of Type "J" or Type "K" thermocouples or
millivolts are made via internal switch and jumper settings (see Sections 2.4.1 and 2.4.3).
1.3 Digital Word Map
Since the module requires a 32-bit input word, the temperature/millivolt data value is placed into the
lower 16-bits (bits 0-17 octal) for transmittal to the PLC (as a V-memory location). As shown in the
following figure, bit 17 is not used for the data value and is always 0. The LSB (bit 0) is used to note
values which are "overrange".
The first 8 bits (20-27 octal) of the upper 16 bits are used for channel status and are read as X values.
Bits 30-37 (octal) are not used.

CTI 2451 Installation and Operation Guide 3
Figure 4 Example Change in Input Level
Figure 5 Effect of Temperature Input on Module Performance
1.4 Thermocouple Input to Digital Conversion
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 (bits 0-17) = Degrees X10
Millivolt Mode, Digital Word (bits 0-17) = Millivolts X100
As an example, the following figure illustrates the effects of a change in input level going from 3.2
degrees to 102.4 degrees in the Thermocouple Input Mode.
1.5 Effect of Out-of Range Input Signals
Thermocouple inputs exceeding the ANSI standard of 760 degrees C for Type "J" or 1372 degrees C for
Type "K" will cause the overrange bit to be set. A maximum temperature of 761 degrees C for Type "J"
or 1373 degrees C for Type "K" will be returned to the PLC for any positive overrange input.
Similarily an input below 0 degrees C for Type "J" or 0 degrees C for Type "K" will cause the overrange
bit to be set. A temperature of 0.1 degree C will be returned to the PLC for Type "J" and Type "K".

4CTI 2451 Installation and Operation Guide
Figure 6 Effect of Voltage Input on Module Performance
Figure 7 Input Resolution
Millivolt inputs exceeding 55.00 millivolts will cause the overrange bit to be set. A reading of 55.01
millivolts will be returned to the PLC for any positive overrange input.
Similarly a millivolt input below 0 millivolts will cause the overrange bit to be set. A reading of 0.01
millivolt will be returned to the PLC for any negative input.
1.6 Resolution
The module has a resolution of approximately 0.2 degrees C, 0.4 degrees F or exactly 0.02 millivolts.
The chart below shows the corresponding input resolution for each of the input configuration modes:

CTI 2451 Installation and Operation Guide 5
CHAPTER 2. INSTALLATION
The installation of the Eight Channel Thermocouple Input Module involves the following steps:
1. Planning the installation
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 2451 requires 2.8 watts of +5V 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 anti-static bag. Do not discard the
anti-static bag. You will need it for the following configuration procedure.

6CTI 2451 Installation and Operation Guide
CAUTION:
DO NOT attempt to calibrate.
Figure 8 Jumper Locations
2.4 Configuring the Module
The Model 2451 must be configured for Type "J" or Type "K" non-grounded thermocouples or millivolt
range and digital filtering/no filtering mode before wiring the input connectors and inserting the module
into the I/O base. As shipped, all input channels are configured Type "J", thermocouples, degrees Celsius
and digital filtering enabled (see Figure 8).
Changing the module input channel configuration involves the following steps:
1. Select millivolt or temperature input
2. Selecting Type "J" or Type "K" thermocouple input mode for each channel
3. Selecting digital filtering or no filtering for the module
4. Logging the configuration jumper settings for future reference
Each of these steps is described in the following sections.

CTI 2451 Installation and Operation Guide 7
Figure 9 Factory Configuration Jumper Settings
2.4.1 Select Millivolt or Temperature Input
Locate jumper JP36 (MILLIVOLT/TEMP jumper in Figure 8) on the 2451 card. Select either Millivolts
or Temperature for the module by positioning the jumper in MILLIVOLT or TEMP position. In the
millivolt mode, jumpers JP1-16, JP35 and DIP switch SW1 are ignored by the 2451.
2.4.2 Selecting Type "J" or Type "K" Thermocouple Inputs
Select the cold junction compensation for each channel by selecting the correct jumper (JP1-16) for each
channel.
Select the correct linearization table by locating by DIP switch 1 (SW1 in Figure 8) on the 2451 circuit
card and select either Type "J" or Type "K" thermocouple for each of the eight inputs by moving each
switch to the proper position. The "ON" position corresponds to Type "J" thermocouple input.
2.4.3 Selecting Digital Filtering
Locate the Digital Filtering Jumper JP34 (see Figure 8). 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.

8CTI 2451 Installation and Operation Guide
Figure 10 Screw Terminal Block Wiring
2.4.4 Select Degrees Fahrenheit or Celsius
Locate the temperature scaling jumper JP35 on the left hand side of the module (see Figure 8) and select
either degrees Fahrenheit or Celsius by positioning the jumper in the FAHRENHEIT or CELSIUS
position.
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 at the back of the module when inserting or removing the
module.
2.6 Wiring the Input Connectors
Thermocouple input signals are accepted through a screw terminal connector block located on the front
of the module. Consult the thermocouple manufacturer's recommendations for selecting the input wire
type and size.

CTI 2451 Installation and Operation Guide 9
CAUTION:
Only non-grounded thermocouples are to be used.
All GND terminals on the 2451 terminal block (see Figure 10) are common to each other. They are
provided as a convenient termination point for cable shields. All input terminals are isolated from the PLC
up to 1500VDC.
2.6.1 Wiring Guidelines
To avoid noise problems, follow these guidelines when installing the module.
!Use the shortest possible wires.
!Avoid placing signal wires parallel to high-energy wires. If the two must meet, cross them
at right angles.
!Avoid bending the wire into sharp angles.
!Use wireways for wire routing.
!When using shielded wires, ground them only at the module end for better noise
immunity.
!Place wires so that they do not interfere with existing wire.

10 CTI 2451 Installation and Operation Guide
NOTE:
All unused channels should be shorted from the + to the - terminals to prevent saturation of the
input amplifier. Failure to do so will result in erroneous readings on adjacent channels.
Figure 11 Thermocouple Wiring Example
2.6.2 Wiring Examples
The following example demonstrates hooking up two thermocouples to channels 1 and 2 of the 2451.
The shields of both thermocouples are connected to terminal 3 GND connector.