CTI 2550-A Operating instructions

2550-A
EIGHT CHANNEL
ISOLATED ANALOG INPUT MODULE
INSTALLATION AND OPERATION GUIDE
Ver. 2.2
CTI Part # 062-00197-022
*062-00197-022*
2550-AIOG 092005 $25

ii CTI 2550-A Installation and Operation Guide

CTI 2550-A Installation and Operation Guide iii
Copyright © 2005 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 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.

iv CTI 2550-A Installation and Operation Guide

CTI 2550-A Installation and Operation Guide v
Figure 1 The 2550-A 8-Channel Isolated Analog Input Module
PREFACE
This Installation and Operation Guide provides installation and operation instructions for the
CTI 2550-A Eight Channel Isolated Analog Input Module for SIMATIC® 505 programmable
controllers. We assume you are familiar with the operation of SIMATIC® 505 series programmable
controllers. Refer to the appropriate SIMATIC® user documentation for specific information on the
SIMATIC® 505 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
.

vi CTI 2550-A Installation and Operation Guide

CTI 2550-A Installation and Operation Guide vii
NOTE:
Notes alert the user to special features or procedures.
WARNING:
Warnings alert the user to procedures which could damage equipment and endanger the user.
CAUTION:
Cautions alert the user to procedures which could damage equipment.
USAGE CONVENTIONS

viii CTI 2550-A Installation and Operation Guide

CTI 2550-A Installation and Operation Guide ix
TABLE OF CONTENTS
PREFACE ................................................................... v
USAGECONVENTIONS....................................................... vii
TABLEOFFIGURES ......................................................... xi
CHAPTER1. DESCRIPTION.................................................... 1
1.1FrontPanelDescription................................................. 1
1.1.1ActiveLED ................................................. 1
1.1.2 Input Connector for Channels 1-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2AsynchronousOperation ................................................ 2
1.3ImmediateI/O ........................................................ 2
1.4UnipolarorBipolarMode ............................................... 2
1.5VoltageorCurrentMode................................................ 2
1.6DigitalWordMap..................................................... 2
1.7AnalogtoDigitalConversion............................................. 4
1.7.1UnipolarModeConversion ...................................... 4
1.7.2BipolarModeConversion ....................................... 4
1.7.3ExampleConversion ........................................... 5
1.8EffectofOut-of-RangeInputSignals....................................... 5
1.8.1UnipolarMode ............................................... 6
1.8.2BipolarMode ................................................ 6
1.9UsinganInputwith20%Offset........................................... 8
1.9.1 Using the Module with 20% Offset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.10Resolution.......................................................... 9
CHAPTER2. INSTALLATION ................................................. 11
2.1PlanningtheInstallation ............................................... 11
2.1.1 Calculating the I/O Base Power Budget . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.1.2InputSignalWiring .......................................... 11
2.2UnpackingtheModule................................................. 12
2.3ConfiguringtheModule................................................ 13
2.3.1 Selecting Voltage or Current Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.3.2SelectingVoltageRange ....................................... 14
2.3.3 Selecting Unipolar or Bipolar Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.3.4SelectingDigitalFiltering ...................................... 15
2.3.5SelectingOffsetScaling ....................................... 15
2.3.6 Selecting Advanced Operating Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.3.7 Configuring DIP Switches to Report Hardware Configuration . . . . . . . . . . . 16
2.4InsertingtheModuleintotheI/OBase..................................... 16

xCTI 2550-A Installation and Operation Guide
2.5WiringtheInputConnectors ............................................16
2.5.1 Connecting Voltage Input Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.5.2 Connecting Current Input Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.5.3ConnectingtheShieldWiring ................................... 18
2.6 Installing the Screw Terminal Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.7CheckingModuleOperation ............................................20
CHAPTER3. TROUBLESHOOTING.............................................21
SPECIFICATIONS ............................................................23
JUMPERSETTINGSLOGSHEET ...............................................25
LIMITEDPRODUCTWARRANTY ..............................................29
REPAIRPOLICY ............................................................. 31

CTI 2550-A Installation and Operation Guide xi
TABLE OF FIGURES
Figure 1 The 2550-A 8-Channel Isolated Analog Input Module ........................... v
Figure 2 2550-A Front Panel ..................................................... 1
Figure 3 Word Input to the PLC from the Module (Unipolar) ............................. 3
Figure 4 Word Input to the PLC from the Module (Bipolar) .............................. 3
Figure 5 Example of Change in Input Level .......................................... 5
Figure 6 Voltage Input Limits (Unipolar) ............................................ 6
Figure 7 Voltage Input Limits (Bipolar) ............................................. 6
Figure 8 Overrange Word Value (Unipolar) .......................................... 7
Figure 9 Underrange Word Value (Unipolar) ......................................... 7
Figure 10 Overrange Word Value (Bipolar) ......................................... 7
Figure 11 Underrange Word Value (Bipolar) ......................................... 8
Figure 12 Input Resolution ....................................................... 9
Figure 13 Factory Configuration Jumper Settings ..................................... 14
Figure 14 Configuration Jumper Locations .......................................... 15
Figure 16 Screw Terminal Connector Wiring ........................................ 17
Figure 17 Shield Wire Termination ................................................ 19
Figure 18 Input Connector Assembly .............................................. 19
Figure 19 Example I/O Configuration Chart ......................................... 20
Figure 20 Troubleshooting Matrix ................................................ 21
Figure 21 Jumper Settings Log ................................................... 25

xii CTI 2550-A Installation and Operation Guide

CTI 2550-A Installation and Operation Guide 1
Figure 2 2550-A Front Panel
CHAPTER 1. DESCRIPTION
The Eight Channel Analog Input Module is a member of Control Technology’s family of I/O modules
compatible with the SIMATIC® 505 programmable controllers. The Model 2550-A is designed to
translate an analog input signal into an equivalent digital word which is then sent to the programmable
controller (PLC).
1.1 Front Panel Description
1.1.1 Active LED
The Active LED will be illuminated when the module is functioning normally. If the Active LED is not
lit, or is blinking, refer to Chapter 3 for troubleshooting.

2CTI 2550-A Installation and Operation Guide
1.1.2 Input Connector for Channels 1-8
This connector provides wiring terminals for channels 1-8 for either voltage or current inputs.
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 analog inputs in one
module update (4 milliseconds maximum) and store the translated words in buffer memory. The PLC
retrieves the stored words from the module buffer memory at the start of the I/O scan.
1.3 Immediate I/O
The Model 2550-A Analog Input Module is fully compatible with the Immediate input instruction for
the SIMATIC® 545 and 555 PLCs.
1.4 Unipolar or Bipolar Mode
Each input channel may be configured to accept either bipolar or unipolar input signals. Selection of
unipolar or bipolaar mode is made via an internal jumper (see Section 2.3.3).
1.5 Voltage or Current Mode
Each of the module’s eight channels may be configured to receive either voltage or current analog input
signals. For unipolar input signals, the range is 0 to 5 VDC, 0 to 10 VDC or 0 to +20 mA. For bipolar
input signals, the signal range is -5 to +5 VDC, -10 to +10 VDC or -20 to +20 mA. Selection of
voltage or current mode and voltage range are made via internal jumpers (see Sections 2.3.1 and 2.3.2).
1.6 Digital Word Map
A unipolar analog input signal is translated into a 12-bit plus sign bit digital word. A bipolar input
signal is translated into an 11-bit digital word plus 1-bit for the polarity sign. Since the PLC requires a
16-bit input word, the 12-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 four bits not used for the digital word, one is used to
show the sign of the word, one is used to note values which are “overrange”, and the remaining bits are
not used and are set to zero.

CTI 2550-A Installation and Operation Guide 3
Figure 3 Word Input to the PLC from the Module (Unipolar)
Figure 4 Word Input to the PLC from the Module (Bipolar)
As shown in the following figure, for a bipolar word input of the five bits not used for the digital word,
one is used to show the sign of the word, one is used to note values which are “overrange”, and the
remaining bits are not used and are set to zero.

4CTI 2550-A Installation and Operation Guide
1.7 Analog to Digital Conversion
1.7.1 Unipolar Mode Conversion
The following equations may be used to calculate the digital word which will result from a particular
voltage or current input in the Unipolar input Mode:
Input voltage (V) x 32000
0 to 5V Input Range Mode, Digital Word (WX)= ---------------------------------
5 volts
Input voltage (V) x 32000
0 to 10V Input Range Mode, Digital Word (WX)= ---------------------------------
10 volts
Input current (mA) x 32000
0 to 20mA Input Range Mode, Digital Word (WX)= -----------------------------------
20 mA
1.7.2 Bipolar Mode Conversion
The following equations may be used to calculate the digital word which will result from a particular
voltage or current input in the Bipolar Input Mode:
± Input voltage (V) x 32000
-5 to +5V Input Range Mode, Digital Word (WX)= -----------------------------------
5 volts
± Input voltage (V) x 32000
-10 to +10V Input Range Mode, Digital Word (WX)= -----------------------------------
10 volts
± Input current (mA) x 32000
-20 to +20 mA Input Range Mode, Digital Word (WX)= ------------------------------------
20 mA

CTI 2550-A Installation and Operation Guide 5
Figure 5 Example of Change in Input Level
1.7.3 Example Conversion
As an example, the following figure illustrates the effects of a change in input level going from 1.25 to
2.5mV in the 0 to 5V Unipolar Input Mode. (For the 0 to 10V and 0 to 20mA Unipolar Input Modes,
or the Bipolar Modes, refer to the formulas given in Sections 1.6.1 and 1.6.2 to determine the digital
word which results from a particular input.)
1.8 Effect of Out-of-Range Input Signals
The Model 2550-A utilizes the overrange and underrange bit to indicate when a channel has reached
individual limits. The value of the overrange or underrange condition varies from channel to channel.
The reason for this is that as a channel is calibrated all of the gains and offsets and dynamic ranges of
the analog to digital converter of the system are compensated for in each analog input channel.
Therefore the point at which the analog to digital converter reaches a saturation point and can no longer
produce a change in counts for corresponding change in input signal is called the overrange or
underrange limit of the channel. This level is different for every channel. In the figures below, (sections
1.8.1 and 1.8.2), the limits for the overrange and underrange values are the minimum limits for a given
channel. The actual limits for an individual channel may be greater.

6CTI 2550-A Installation and Operation Guide
Figure 6 Voltage Input Limits (Unipolar)
Figure 7 Voltage Input Limits (Bipolar)
1.8.1 Unipolar Mode
Signals falling below the lower limits in 0 to 5V Input Mode or 0 to 10V Input Mode are translated
into a digital word that includes the addition of Bit 16 to indicate an overrange or underrange condition.
Note that although the digital word may approach zero as the analog input signal approaches the
minimum given range, the digital word will never actually be zero. In fact the underrange capability of
any channel in Unipolar Mode may produce a negative value to the PLC for a number of counts before
the underrange bit is set.
1.8.2 Bipolar Mode
In Bipolar Mode signals above or below the upper and lower limits in the -5 to +5VDC or
-10 to +10VDC range are translated to a digital word and also utilize the overrange and underrange bit.
The actual limit for each channel will vary from channel to channel as described above.

CTI 2550-A Installation and Operation Guide 7
Figure 8 Overrange Word Value (Unipolar)
Figure 9 Underrange Word Value (Unipolar)
Figure 10 Overrange Word Value (Bipolar)
Figures 8 and 9 show the binary values of typical overrange and underrange conditions for Unipolar
mode.
Figures 10 and 11 show the binary values of typical overrange and underrange conditions for Bipolar
Mode.

8CTI 2550-A Installation and Operation Guide
Figure 11 Underrange Word Value (Bipolar)
NOTE:
This function is new and was not supported in the original 2550 product.
When enabled with JP1 all 8 inputs are scaled for offset mode.
1.9 Using an Input with 20% Offset
Some applications use transducers that provide 1 to 5 volts (4 to 20mA) input signals instead of
0 to 5 volt (0 to 20mA) input signals. You can allow for this 20% offset by including some additional
instructions in your RLL (Relay Ladder Logic) program.
First, subtract 6400 from the input data word (WX). Then, multiply the result by 125 and divide the
product by 100. This yields the following equation:
(WX -6400) x 125 ÷ 100 = 20% offset data word
Consult your PLC programming manual (or program design guide) for information about RLL
instructions used in the conversion.
1.9.1 Using the Module with 20% Offset
If all 8 inputs are used in offset mode the Model 2550-A may be configured to perform the offset
calculation automatically. (See Figure 14 Configuration Jumper Locations). Jumper JP1 when enabled
will configure the module such that all inputs will be scaled for 1-5VDC or 4-20mA operation. No
further relay ladder logic is required for input processing.