audit-signature.md

Audit Signature (CFR21 workflow)

The Audit Signature is a special type of object that can be added to any variable in FactoryTalk Optix, it allows to track the changes on the variable and who made those changes, this is specially useful for CFR21 compliance.

The following APIs are intended to be used at DesignTime to prepare the InformationModel with the necessary Audit Signatures.

Add signature to a variable

[ExportMethod]
public void AddSignatureToVariable()
{
    var sourceVarPointer = LogicObject.GetVariable("SourceVariable") ?? throw new ArgumentException("Cannot find source variable");
    var sourceVar = InformationModel.GetVariable(sourceVarPointer.Value) ?? throw new ArgumentException("Cannot find source variable");
    // Create the audit variable
    var sourceVar = InformationModel.Make<AuditInfo>("AuditSigning Signature");
    sourceVar.Add(auditVar);
}

Add signature on all bits of a word

[ExportMethod]
public void CreateAuditOnVariableSingleBits()
{
    // Check if InputVariable is populated
    var sourceVarPointer = LogicObject.GetVariable("SourceVariable") ?? throw new ArgumentException("Cannot find source variable");
    var sourceVar = InformationModel.GetVariable(sourceVarPointer.Value) ?? throw new ArgumentException("Cannot find source variable");

    // Check if TargetFolder is populated
    var targetFolderPointer = LogicObject.GetVariable("TargetFolder") ?? throw new ArgumentException("Cannot find target folder");
    var targetFolder = InformationModel.Get<Folder>(targetFolderPointer.Value) ?? throw new ArgumentException("Cannot find target folder");

    // Prepare object for the method
    var methodArguments = new object[] { sourceVar, targetFolder };

    // Run the method in a separate thread
    var myTask = new LongRunningTask(CreateSingleBits, methodArguments, LogicObject);
    myTask.Start();
}

private void CreateSingleBits(LongRunningTask task, object methodArgumentsObj)
{
    // Extract the method arguments
    var methodArguments = (object[]) methodArgumentsObj;
    var sourceVar = (IUAVariable) methodArguments[0];
    var targetFolder = (Folder) methodArguments[1];

    // Variable to store the number of bits
    var numberOfBits = 0;

    // Get the type of the source variable. Add new datatypes if needed
    if (sourceVar.DataType == OpcUa.DataTypes.Int32 || sourceVar.DataType == OpcUa.DataTypes.UInt32)
        numberOfBits = 32;
    else if (sourceVar.DataType == OpcUa.DataTypes.Int16 || sourceVar.DataType == OpcUa.DataTypes.UInt16)
        numberOfBits = 16;
    else if (sourceVar.DataType == OpcUa.DataTypes.Float)
        numberOfBits = 32;
    else if (sourceVar.DataType == OpcUa.DataTypes.Double)
        numberOfBits = 64;
    else
        throw new ArgumentException("Unsupported data type");

    // Create the variable for each bit and add the auditing
    for (int i = 0; i < numberOfBits; i++)
    {
        // Create the new variable
        var newVariable = InformationModel.MakeVariable($"{sourceVar.BrowseName}_Bit{i}", OpcUa.DataTypes.Boolean);
        newVariable.SetDynamicLink(sourceVar, DynamicLinkMode.ReadWrite);

        // Modify the dynamic link to read only the bit using HasDynamicLink reference
        var dynamicLinkVariable = newVariable.Refs.GetVariable(FTOptix.CoreBase.ReferenceTypes.HasDynamicLink) as IUAVariable;
        if (dynamicLinkVariable != null)
        {
            dynamicLinkVariable.Value = (string)dynamicLinkVariable.Value + $".{i}";
        }

        // Create the audit variable
        var auditVar = InformationModel.Make<AuditInfo>("AuditSigning Signature");
        newVariable.Add(auditVar);

        // Check if the variable already exists and delete it
        if (targetFolder.Children.OfType<IUAVariable>().Any(v => v.BrowseName == newVariable.BrowseName))
            targetFolder.Get(newVariable.BrowseName).Delete();

        // Add the variable to the target folder
        targetFolder.Add(newVariable);
    }
}