FIELD OF INVENTION
The present invention generally relates to a development of intelligent test jig for digital output module used in the distributed control system (DCS). In particular the present invention relates to a system and method to test the Digital Output Module in a fully automatic environment.
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 hydro 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 issued 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 issues 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 digital output module is used to send process values/ setpoints etc. to various devices.
Usually the digital output modules are tested as per the test procedure available with the module. To test the functionality of the module, a series of commands are issued through a Terminal Emulation Software such as "Hyper terminal". Module location and channel no are part of the command. At various stages of testing, resistor-led circuit 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 return values to be matched as per the documentation to derive the test result.

OBJECTS OF THE INVENTION
The main object of the present invention is to provide an intelligent system that can do the functional test of digital output module in a fully automatic method without any manual intervention.
SUMMARY 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 method of testing the digital output modules.
The module under test will be connected to the PC using controller and a null modem cable. The Intelligent 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 digital output module with a single dick of mouse button. The test will be canned out automatically and the result will be 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 double clicking on the failed test row in the graphical user interface. The actual circuit diagram of the module will be opened and the probable faulty components will be highlighted in red color with flashing.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The invention can now be explained with reference to the accompanying
drawings where
Figure 1 shows in block diagram of Intelligent test jig set up for DO module.
Figure 2 shows functional test specified for DO module.
Figure 3 shows intelligent hardware developed for automated testing of DO
module. Figure 4 shows sample screen shot of user interface Figure 5 Graphical user interface for DO test Figure 6 DO Test Result
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION
The standard procedure for testing the digital output module is by connecting a PC to the module using a controller and a null modem cable as shown in Figure 1. Manual commands are issued and the responses are analyzed to arrive at the result Different circuits need to be connected to the channels during various 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 Digital output module functional test specification reveals that ~24 commands to be issued, ~4 data page entries to be correlated and 25 manual noting to be made to arrive at the final test result/ status of the module.
This translates to 53 manual interventions required for testing single DO module.
The various tests to be carried out for the DO module is shown in Figure 2.
This invention ts related to 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.
The Intelligent test jig is developed using various hardware and software
components. A user friendly Graphical User Interface (GUI) interacts with the
user and the DO module through controller. The hardware comprises of an
Microcontroller with associated peripheral interfaces and the circuits required to
be fed to the module. This hardware circuit is connected to the DO module
through a spedal 25 core pre-fabricated cable designed for intelligent test jig.
The cable assembly consists of devices to read the intensity of light emitted by theLEDs.

The GUI of Intelligent test jig is installed in a workstation/ PC. The hardware of intelligent test jig is connected to the PC through the USB port. The Intelligent 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 no. to initiate the DO 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.
DO module can be tested either in auto mode or in semi-auto mode. In auto mode the entire functional test will be carried out automatically without any manual intervention. In semi-auto mode user will be asked to notice different status and feed resistors as per DO module production test specification.
In Auto mode, intelligent test jig will automatically carry out all the tests in a sequential manner without user intervention. On completion of the test, intelligent test jig beeps three times to alert the user that the test is completed as shown in Figure 6.
In Semi-Auto mode, intelligent test jig will carry out all the tests in a sequential manner requesting user intervention. User need to note down the LED status and manually feed the data to intelligent test jig and also connect the necessary

circuits to the individual channels as and when required and indicated by intelligent test jig. Issue of commands and the data page bit evaluation will be carried out by the intelligent test jig.
If a failure is announced for any of the "Functional Verification'' test, double dick on the respective row for getting tips on troubleshooting. The schematic page related to the specific function will be displayed with the probable faulty component flashing in red color. If the probable faulty components identified are in different schematic pages, the "Next" and "Previous" buttons are enabled/ disabled accordingly. This feature will help the module repair engineer to quickly fix the problem.
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, SI 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 recorded 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 area/ components will also be marked in the report file.

Steps and methods followed for functional testing of Digital Output Module:
1. At startup: When a Digital Output module is started, all its yellow (8 In total) signal lights are switched on for about half a second and then reset. If any or all signal lights fail to switch on and off, the card is either faulty or it has been installed incorrectly on the mounting base.
2. Testing Serial Buses:
a. The module type is checked via both serial buses (main and auxiliary),
b. Set the I/O card onto the main bus
c. Read the module type from byte 0 and the field interface type from
byte 1 on page three
d. Check for the reply
e. Set the I/O card onto the auxiliary bus
f. Read the module type from byte 0 and the field interface type from
byte 1 on page three
g. Check for the reply
h. Set the I/O card back onto the main bus
i. If this check is successful, the following blocks work: 5-volt supply line
and its peripheral components RS-485 bus buffers A1-A2 and their
peripheral components D7/D3 controller G1 crystal

3. Testing Reading of the Card Address:
a. Addresses are set, for the card address lines.
b. The addresses to be tested are (mounting base address + card slot
address)
c. Issue commands to test the address
d. If the address is formed correctly, the D6 buffer is functionally ok.
4. Testing the Output Channels
a. Configuration
The output channels are configured one by one with the commands
b. Output channel function test
a. Connect two resistors (60 (5W) and 60 (5W)) in series between the
output channel 0 COM pin and process voltage 0V, and connect a
red signal light (20mA) with its own series resistor 1k alongside one
of the resistors. Connect process voltage (24VDC) to channel 0
NO/NC pin.
b. Set 0 as channel 0 mode with the command
c. Check that following signal lights are off: the yellow channel 0
signal light and the red signal light connected to the output
d. Set 1 as channel 0 mode with the command
e. Check that following signal lights are on: the yellow channel 0
signal light and the red signal light connected to the output

f. Repeat steps a to f for channels 1-7
g. Once the test has been performed successfully, the following
components work: Output-channel optos A1-A4, circuits D1, V13,
and peripheral components H1-H8 signal lights Connecting
components K1-K8 Output current limiters F1-F8 and their
peripheral components This completes the Digital Output module
testing processes

WE CLAIM
1. A system to test the digital output module in a fully automatic environment
comprises:
a Graphical User Interface (GUI) to interact with the user;
a digital output means;
a controller means to carry out the tests of intelligent test jig in a sequential
manner.
2. A system to test the digital output module as claimed in claim 1, wherein the Graphical User Interface (GUI) of intelligent test jig is positioned in a work station.
3. A system to test the digital output module as claimed in claim 1, wherein the intelligent test jig comprises a display means.
4. A system to test the digital output module as claimed in claim 1, wherein if a failure is announced for any of the "Functional Verification" test, the system provides steps of troubleshooting to the operator.
5. A method to test the digital output module in a fully automatic environment comprises the steps as illustrated w.r.t. the accompanying drawings.