FIELD OF INVENTION:-
The present invention generally relates to a development of a test jig for analog input module used in the distributed control system (DCS).
BACKGROUND OF THE INVENTION:-
In a distributed control system (DCS) the input/output modules and the controllers in the central control room process the data captured from various sensors, actuators, and field devices in the generating plants for example, a thermal power plant. The data is centrally stored in the storage mechanism in the control room and this data is processed by human machine interface for monitoring and decision-making on the performance of the total system.
A typical distributed control system has mainly the following components:-field sensors, transmitters, actuators etc; input /output module connected to the field elements for data acquisition; controller unit for processing the acquired data and also for issuing the commands for field operation,HMI system for data display and control; data storage unit and plant network, which interconnects all the controllers and the HMI.
The input/output modules are connected to the field elements and the Input modules acquire data provided by the field elements. Commands generated through the controller are sent to the output field elements through the output modules. The logic to process the data is programmed in the controller and controller generates monitoring and control instructions so as to implement the desired functioning schedule of the plant. The controller processes the data available in the Input module and take decisions based on the logic built in it. If the decision is to output some values to a field device, then this is sent out through the output module.
In the Distributed Control System the input output modules are used as an

interface between the control system and the field devices. The analog input module is used to receive process values! set points etc. to various devices.
Usually the analog input modules are tested as per the test procedure available with the module. To test the functionality of the module, a series of commands are generated through a Terminal Emulation Software such as "Hyper terminal". Module location and channel no are part of the command. At various stages of testing, accurate milliampere current sources, resistor circuits etc needs to be connected to the channels one by one, and status of LEDs of the module need to be noted down. LED status and the values returned by the module to be matched as per the documentation to derive the test result.
OBJECTS OF THE INVENTION:-
a) The main object of the present invention is to provide system that can perform the functional test of analog input module in a fully automatic method without any manual intervention.
b) Another object of the invention is development of an intelligent test jig to automate the laborious test procedure to reduce the time taken for testing and also to reduce or nullify the manual errors.
STATEMENT OF THE INVENTION:-
The system of the present invention has various hardware and software components that works in tandem to achieve the goal of fully automatic and intelligent system of testing the analog input modules.

The module under test will be connected to a computer using controller and a null modem cable. A test jig is connected to the channels of the module. The test jig scans the backplane where the modules are connected and displays to the user. The user then selects a module and performs the functional test of analog input module. The test is carried out automatically and the result is displayed to the user.
In case the module reports a failure for any of the specified test, the user can find out the faulty electronic component by selecting the failed test row in the graphical user interface. The circuit diagram of the module is displayed and the faulty components are indicating.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:-
It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system or methods in accordance with embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which:
The invention can now be explained with reference to the accompanying drawings where
Figure 1 shows in block diagram of test jig set up for Al module.
Figure 2 shows functional test specified for Al module.
Figure 3 shows intelligent hardware developed for automated testing of Al module.

Figure 4 shows sample screen shot of user interface. Figure 5 Graphical user interface for Al test Figure 6 Al Test Result
The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT:
The standard procedure for testing the analog input module is by connecting a module to the module using a controller and a null modem cable as shown in Figure 1. Manual commands are generated and the responses are analyzed to arrive at the result. Different circuits are connected to the channels at separate stages of the testing. The ON-OFF status of the LEDs needs to be checked manually. Manual method of testing is a laborious procedure that involves connecting various circuits at different point of time as and when it is required, one by one to each channel. This manual procedure is vulnerable to errors creeping in due to monotonous nature of the test procedure.
A quick analysis of Analog input module functional test specification reveals that -124 commands to be issued, -77 data page entries to be correlated and 41 manual noting to be made to arrive at the final test result! status of the module .


This translates to 242 manual interventions required for testing single AI module. The various tests to be carried out for the AI module is shown in Figure 2. A user friendly Graphical User Interface (GUI) interacts with the user and the AI module through controller. The hardware comprises of an Microcontroller with associated peripheral interfaces and the circuits required to be fed to the module. The circuit is connected to the AI module through a 25 core pre-fabricated cable configured for the test jig. The cable assembly consists of devices to read the intensity of light emitted by the LEDs.
The GUI of test jig is installed in a workstation/computer. The hardware of intelligent test jig is connected to the computer through the USB port. The test jig hardware has an LCD display that displays the current status of the test as shown in Figure 3.
Double click on the respective slot number. to initiate the AI module test as shown in Figure 4.
Module type serial no., firmware version no. and location of the module in the mounting base are displayed in the 'Module' group as shown in

Figure 5.
Al module can be tested in auto mode wherein the entire functional test will be carried out automatically without any manual intervention.
In Auto mode test jig will automatically carry out all the tests in a sequential manner without user intervention. On completion of the test, test jig alerts the user that the test is completed as shown in Figure 6.
If a failure is announced for any of the “Functional Verification” test, a schematic page related to the specific function is displayed indicating the probable faulty component. If the probable faulty components identified are in different schematic pages, the "Next" and "Previous" buttons are enabled/disabled accordingly.
Module test report will be generated automatically at the end of the functional test. The first line of the report file indicates the module type. The date and start time of the test, 81 No. of the module, and the version no of the firmware will also be recorded. All the functional tests carried out with the result of each test are ecorded in the report. The date and time of completion of the test will be displayed at the end of the report.
If the module fails during any of the functional tests, then the probable faulty areal components will also be marked in the report file.
Advantages:-
A novel method of testing Analog input module in a bulk manufacturing
environment.
Built-In intelligence to carry out all the functional tests of for Analog

Input module and analysis of the result.
Fully automated Analog Input module test jig, the user can carry out all the function tests with a single click of mouse button . No manual intervention required in "Auto mode".
More efficient system compared to manual method of testing for Analog Input module.
Very less cycle time in comparison to manual method of testing for Analog Input module.
Error less system as the Analog Input module test jig is intelligent and
fully automated (no fatigue errors or monotonous nature of test).
An innovative feature built-in to assist the module repair engineer
in troubleshooting the failed Analog Input module.
Detailed report generation with troubleshooting tips for Analog Input.

We claim:-
1. A system for testing the analog input module in a distributed control system 5 comprising a test jig interfaced with associated electronics in which a graphical user interface (GUI) interacts with an artificial intelligence module (AI) through a controller to output result of various tests performed.
2. A system for testing the analog input module as substantially descried and illustrated herein with reference to the accompanying drawings.