Software Specification

Comparer

insite GmbH

Introduction#

A Comparer is a software component that is part of the IDAT system and is used for a cyclical comparison of data. Various comparers exist, depending on the type of data they observe. Depending on the comparison results, different actions can be defined.

Purpose and Objective##

A Comparer is an interchangeable component that monitors and compares data (files, Excel data, PLC data ...)

Definitions, Acronyms, Abbreviations##

PLC: Programmable Logic Controller
SPS: Speicher Programmierbare Steuerung
LibNoDave: A free library for the communication with a PLC
Data definition file (DDF): A file that describes the structure and mapping of (PLC) data
Mapping: A variable is mapped to a defined data area

General Description#

The special features and setting options of the software are described below.

System Environment##

The software is written in C# with Visual Studio 2010 for the Target framework .NET 4.0.

.NET 4.5 is not used since it does not guarantee any compatibility with XP.

Framework##

This components are a part of IDAT and are also configured using the IoC components of IDAT (for more details, please refer to the chapter Configuration).

Host application##

In this installation and use case, there is one host application that uses comparers. It is called "IMON" and has it's own "IMON User Guide".

Comparers#

The following section examines the currently existing comparers and points out the options and configurations.

All comparers are linked to the application by implementing the following interface:

arer
{
    public interface IComparer
    {
        void Configure(XElement xmlSetup);
        void RunOnce(); 
        void Start();
        void Stop();
    }
}

FileComparer##

This component compares files as well as their contents if necessary (see ContentComparison). On a change of the monitored file, an event can be created.

Configuration###

<Comparer impl="IMONFileComparer">
    <PollingCycle>10</PollingCycle>
    <Source><![CDATA[D:\Test.xlsx]]></Source>
    <Destination><![CDATA[D:\tmp\]]></Destination>
    <Executor>
        ...
    </Executor>
</Comparer>

Parameter	Description
PollingCycle	Test every x seconds for a change
Source	The files to be checked are specified here
	(file name with wildcards possible)
Destination	Destination directory. It contains the last version of the file. The
	source file may change and is compared to the version stored here
Executor	Actions that are executed in the case of inequality

Execute####

<Executor>
    <Execute filter="(.*\.xlsx)" eventHandler="IDATExecutor" 
             errorEventHandler="IDATErrorExecutor"  
             errorValueName="CurrentErrorCode" hint="none" />
    <Execute filter="(.*\.xlsx)" 
             eventHandler="C:\Execute.bat" />
</Executor>

ContentComparison#####

Attribute	Description
filter	RegEx file filter (e.g.: .*.xlsx for all xlsx files )
eventHandler	Can either be an EventHandler or an executable file
	(see document EventHandler)
errorEventHandler	EventHandler executed when an error occurs
errorValueName	Name of the constant that should record the Errorcode
hint	Not used at present

DataComparer##

This component was developed to integrate interfaces to the PLC. For example, you can implement a handshake protocol that works on different flags written/read by the PLC and the PC to implement a safe data exchange mechanism. You can declare actions that depend on a certain flag in the PLC so it is executed when a certain condition is met.

Such actions can be

Opening batch files or invoking processes.
Writing a block of data to the PLC.
Setting other handshake flags in the PLC.

and more.

Configuration###

<Comparer impl="IMONDataComparer">
    <PollingCycle>3</PollingCycle>
    <DataDefFilename>D:\IDATSchrauberDB.xml</DataDefFilename>
    <OutputFilename>IMONDataComparerOutput.xml</OutputFilename>
    <Actions>
        <Action writeVar="IfError.ErrorCode" eventHandler="IDATExecutor"  />
        <Action writeVar="IfError.ErrorOccured" eventHandler="IDATExecutor"  />
        <Action readVar="IfRead.UpdateRequired" compValue="true" 
                eventHandler="IDATExecutor" errorEventHandler="IDATErrorExecutor" 
                errorValueName="CurrentErrorCode" hint="none" />
        <Action readVar="IfRead.UpdateRequired" compValue="false" 
                writeVar="IfWrite.UpdateRequiredDetected" writeValue="false" 
                errorEventHandler="IDATErrorExecutor" errorValueName="CurrentErrorCode" 
                hint="none" />
        <Action readVar="IfRead.Toggle" compValue="true" writeVar="IfWrite.Toggle" 
                writeValue="false" errorEventHandler="IDATErrorExecutor" 
                errorValueName="CurrentErrorCode" hint="none" />
        <Action readVar="IfRead.Toggle" compValue="false" writeVar="IfWrite.Toggle" 
                writeValue="true" errorEventHandler="IDATErrorExecutor" 
                errorValueName="CurrentErrorCode" hint="none" />
        <Action readVar="IfRead.WriteEnabled" compValue="false" 
                writeVar="IfWrite.DataWritten" writeValue="false" 
                errorEventHandler="IDATErrorExecutor" errorValueName="CurrentErrorCode" 
                hint="none" edge="true" />
    </Actions>
</Comparer>

Parameter	Description
PollingCycle	Test every x seconds for a change
DataDefFilename	Data definition (see documentation Data Definition)
OutputFilename	A dump of the read and written data
Actions	A series of defined actions

Action####

<Action readVar="IfRead.WriteEnabled" compValue="false" edge="true"
                writeVar="IfWrite.DataWritten" writeValue="false" 
                errorEventHandler="IDATErrorExecutor" errorValueName="CurrentErrorCode" 
                hint="none" />

        <Action readVar="IfRead.WriteEnabled" compValue="true" edge="true"
                eventHandler="C:\Action.bat"
                errorEventHandler="IDATErrorExecutor" errorValueName="CurrentErrorCode" 
                hint="none" />

<Action writeVar="IfError.ErrorCode" eventHandler="IDATExecutor"/>

Structure of the variable names: [Mappingname].[Varname]

<Mapping name="IfRead" var="IDATIf" ...>
    <Operations>
        <Read name="WriteEnabled" var="PLCtoIDAT.WriteEnable" active="true" />
    </Operations>
</Mapping>

Attribute	Description
readVar	PLC variable to be read
compValue	Value to be compared with
edge	Execute action only if value changes
writeVar	PLC variable to be written
writeValue	Value to be written
eventHandler	Can either be an EventHandler or an executable file
	(see document EventHandler)
errorEventHandler	EventHandler executed when an error occurs
errorValueName	Name of the constant that should record the Errorcode
hint	Not used at present

Examples:

<Action readVar="IfRead.UpdateRequired" compValue="true"
        eventHandler="IDATExecutor" errorEventHandler="IDATErrorExecutor"
        errorValueName="CurrentErrorCode" hint="none" />

Read the Variable UpdateRequired from the Mapping IfRead (=readVar)
Compare the read value with the value in compValue
If the value is equal, then execute the EventHandler
If an error occurs, then execute the ErrorEventhandler and initialise the constant CurrentErrorCode that is to be defined in the DDF as CONST with the error code

<Action readVar="IfRead.UpdateRequired" compValue="false" 
        writeVar="IfWrite.UpdateRequiredDetected" writeValue="false" 
        errorEventHandler="IDATErrorExecutor" errorValueName="CurrentErrorCode"
        hint="none" />

Read the Variable UpdateRequired from the Mapping IfRead (=readVar)
Compare the read value with the value in compValue
If the value is equal, then set the variable UpdateRequiredDetected (writeVar) from Mapping IfWrite in the data definition to the value defined in writeValue

<Action writeVar="IfError.ErrorCode " eventHandler="IDATExecutor" />

The variable ErrorOccured is written with each call (i.e. cyclic), the value to be written is the value entered in the DDF.

Installation#

The different comparers come as DLLs and are installed via a simple copy operation together with the other IDAT files.

Change Directory#

Author	Date	Remarks
Benjamin Prömmer	August 2013	Creation
Karsten Gorkow	2016-01-15	Revised document