Filter data by tag value, write to database only on change

Problem scenario

I have this item: Kemro.opc.4.IF1.1.92.Mars1.SVs.system.sv_ShotCounter[14]="1562" in OPC Data Logger. I want to take data and write it to MySQL, only when this counter changes.

Requirements:

• Advanced OPC Data Logger Enterprise or a trial version.
• Script Execute plugin.

It is assumed that:

1. You've created a configuration (using the "Green Plus" button in the main window and added an OPC group in the OPC logger and can receive any data from a selected OPC server.

2. You've configured a data export to MySQL.

Solution:

1. Enable highlighted options in the OPC group settings.

Fig.1. OPC group settings

2. Download and install the "Script Execute" plugin.

3. Enable it (fig. 2).

Fig.2. Script Execute plugin

4. Select the plugin in the list and click the "Setup" button below.

5. In the script editor window select "PascalScript" from the "Script type" list

6. Copy and paste the following code. Modify it if necessary. The row sName1:string = 'Kemro.opc.4.IF1.1.92.Mars1.SVs.system.sv_ShotCounter'; contains the name of the controlled OPC tag.

7. Click the "Check" button and verify that the script was compiled successfully.

8. Click the "OK" button and save all changes.

The PascalScript code

var v1,v2:double;
    sName1:string = 'Kemro.opc.4.IF1.1.92.Mars1.SVs.system.sv_ShotCounter';
    sName2:string = 'LAST_VALUE';
begin
 // checks that a variable is stored before
 if IsVariableStored(sName2) then
   // retrieves a stored variable
   v1 := PopVariable(sName2)
 else
   // otherwise initialize our value
   v1 := 0;

 // checks a variable in a data packet
 if IsVariableDefined(sName1) then
  begin
    v2 := GetVariable(sName1);
    // stores a value between script executions
    PushVariable(sName2, v2);

    // the script will discard data packets by the following condition
    if v1 = v2 then
     DiscardDataPacket();
  end
 else
  // discard data also when the counter didn't read yet
  DiscardDataPacket();

end.

Related articles:

• Inserting OPC data to MS Access database through ODBC (features: adding groups and items, inserting to an ODBC database)
• Adding a timestamp in the CSV file (features: OPC groups)
• How to log OPC data to a SQL database.
• OPC to MSSQL: Writing a lot of OPC tags to MS SQL 2008 database
• OPC to MSSQL: Writing several OPC tags to separate columns
• OPC to MySQL: Writing OPC tags to MySQL 5 database
• OPC to a database: Writing OPC tags to a database
• OPC to Excel: Writing OPC data to Excel
• Filtering data by a tag value and write data to a database only when the value will change
• Filtering data out if an OPC tag value is not equal to a specified value
• Processing or storing OPC data by an event from the OPC server
• Aggregating data from multiple servers to one OPC server

OPC and DCOM Configuration on Windows 2008 and Windows 7

• Part 1. Installing OPC Core Components.
• Part 2. OPC and DCOM Configuration. Creating a user and giving access permissions.
• Part 3. Configuring the Windows 2008 and Windows 7 firewall for DCOM and OPC.
• Part 4. DCOM Configuration. Dcomcnfg.
• Part 5. OPC and DCOM Configuration. Typical problems and solutions.

OPC and DCOM Configuration on Windows 10, 11, Windows Server 2019, 2022

• Part 1. Installing OPC Core Components.
• Part 2. OPC and DCOM Configuration. Creating a user and giving access permissions.
• Part 3. Configuring the Windows 10, 11, Windows Server 2019, 2022 firewall for DCOM and OPC.
• Part 4. DCOM Configuration. Dcomcnfg.
• Part 5. OPC and DCOM Configuration. Typical problems and solutions.