FIELD OF THE INVENTION
The present invention relates to an intelligent system for automatized functional
testing of digital input module of distributed control systems.
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 device in the
control room and this data is processed by a human machine interface for
monitoring and decision-making on the performance of the power plant.
A typical distributed control system has mainly the following components:-
field sensors, transmitters, actuators, input / output module connected to the
field elements for data acquisition; a controller unit for processing the acquired
data and transmitting control commands for field operation, a HMI device for
data display and control; a data storage unit, and the 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 the controller
issues monitoring and control instructions so as to implement the desired

functionalities 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 input
module is used to acquire the real-time status of various devices. The digital
input module scans at a very high speed, generally in few milli seconds. The
digital input module is also used at 1 milli second scan rate for Sequence Of
Events (SOE) data acquisition. SOE is an important function in the DCS which is
used to find out the first cause, in case of a trip occurs in the plant.
Usually the digital 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 issued through a Terminal Emulation Software such as "Hyper terminal".
Module location and channel number are part of the command. At various stages
of testing, different values of resistors need to be connected to the input
channels, and status of LEDs of the module need to be noted down. The module
returns values available in the data page. This value needs to be cross checked
with the standard values available in the module production test specification
document. Channel data is presented as 4 bytes information that needs to be
correlated with the expected values. LED status and data page content to be
matched as per the documentation to derive the test result.

OBJECT OF THE INVENTION
It is therefore an object of the present invention to propose an intelligent system
for automatized functional testing of digital input module of distributed control
systems.
SUMMARY OF THE INVENTION
The system of the present invention has various hardware and software
components that works in tandem to achieve the objective of automatized
functional testing of digital input modules.
According to the invention the module under test is connected to a PC using a
controller and a null modem cable. An intelligent test system is connected to the
input channels of the module. The test system 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 input module with a single click of
mouse button. 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 double clicking on the failed test row
in the graphical user interface (GUI). The actual circuit diagram of the module is
then opened and the probable faulty components are 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 a block diagram of Intelligent test system for DI modules.
Figure 2 shows functional test specified for DI modules.
Figure 3 shows sample screen shot of user interface
Figure 4 shows intelligent hardware developed for automated testing of DI
module.
Figure 5 Graphical user interface for DI test
Figure 6 DI Test Result
DETAILED DESCRIPTION OF THE INVENTION
The prior art procedure for testing the digital input module is by connecting a PC
to the module using a controller and a null modem cable. Manual commands are
issued and the responses are analyzed to arrive at the result. Different circuits
need to be connected to the input 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 Input module functional test specification reveals that
~54 commands to be issued, ~37 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 116 manual interventions required for testing a single DI
module.
The various tests to be carried out for the DI module is shown in Figure 2.
This invention is related to development of an intelligent test system 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 system is developed using various hardware and software
components. A user friendly Graphical User Interface (GUI) interacts with the
user and the DI module through a 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 DI module
through a 25 core pre-fabricated cable designed for intelligent test system. The
cable assembly consists of devices to read the intensity of light emitted by the
LEDs.
The GUI of Intelligent test system is installed in a workstation/ PC. The
hardware of intelligent test system is connected to the PC through an USB port.
The Intelligent test system 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 DI module test as
shown in Figure 4.
Module type, serial number firmware version number and location of the module
in the mounting base are displayed in the 'Module' group as shown in Figure 5.
DI module can be tested either in auto mode or in semi-auto mode. In auto
mode the entire functional test is carried out automatically without any manual
intervention. In semi-auto mode user is allowed to notice different status and
feed resistors as per DI module production test specification.
In Auto mode, the intelligent test system will automatically carries out all the
tests in a sequential manner without user intervention. On completion of the
test, the intelligent test system beeps three times to alert the user that the test
is completed as shown in Figure 6.
In Semi-Auto mode, the intelligent test system carries 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 the intelligent test system and also connect
the necessary circuits to the individual channels as and when required and
indicated by the system. Issue of commands and the data page bit evaluation is
carried out by the intelligent test system.
If a failure is announced for any of the "Functional Verification" a test, double
click on the respective row for getting tips on troubleshooting. The schematic
page related to the specific function is 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 enables the module repair engineer to quickly
fix the problem.
Module test report is 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 Number of the module, and the version number of the firmware
are 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 is
displayed at the end of the report.
If the module fails during any of the functional tests, then the probable faulty
area/ components are to be marked in the report file.

WE CLAIM
1. An intelligent system for automatized functional testing of digital input
module of distributed control systems, the distributed control system
(DCS) comprises a plurality of field sensors, transmitters actuators, a
plurality of input and output modules to the field elements for data
acquisition, a controller unity for processing the acquired data and
transmitting corresponding control commands for field operation, a
human-interface (HMI) device for data display, and a data storage unit,
the components of the DCS being interconnected through a plant
network, the intelligent system comprising:-
- a testing device to test the digital input modules of DCS having a
microcontroller with peripheral interfaces and hardware circuits to
feed signals representing test parameters to the module under test,
the hardware circuit being connected to the modules through a
pre-fabricated cable assembly having devices to read the intensity
of light emitted by a plurality of LEDs fixed on the test device to
display multiple test-parameters of the module;
- a graphical user interface (GUI)installed on a workstation and the
hardware circuit of the test device connected to the workstation
through an USB port with built-in feature for assistance in
troubleshooting the module, in case of failure
wherein the system on activation carries out the functional test of the
modules and the test results displayed without manual intervention.

ABSTRACT

The invention relates to an intelligent system for automatized functional testing
of digital input module of distributed control systems, the distributed control
system (DCS) comprises a plurality of field sensors, transmitters actuators, a
plurality of input and output modules to the field elements for data acquisition, a
controller unity for processing the acquired data and transmitting corresponding
control commands for field operation, a human-interface (HMI) device for data
display, and a data storage unit, the components of the DCS being
interconnected through a plant network, the intelligent system comprising a
testing device to test the digital input modules of DCS having a microcontroller
with peripheral interfaces and hardware circuits to feed signals representing test
parameters to the module under test, the hardware circuit being connected to
the modules through a pre-fabricated cable assembly having devices to read the
intensity of light emitted by a plurality of LEDs fixed on the test device to display
multiple test-parameters of the module; a graphical user interface (GUI)installed
on a workstation and the hardware circuit of the test device connected to the
workstation through an USB port with built-in feature for assistance in
troubleshooting the module, in case of failure wherein the system on activation
carries out the functional test of the modules and the test results displayed.