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Help > OPC DA Connect Reference > Read Numeric Variable
Read Numeric Variable

This step allows reading a Numeric variable on a selected OPC Server.

To configure this step open the Edit Step window from Sequence editor.

In the Configuration Dialog Box, select a valid server by navigating over the Network to select a server or by using an expression.

In the Variable Path, select the Numeric Variable to read by navigating on the OPC Server with Variable Browser or by using an expression.

Tip  Only compatible variables are listed in the tree of the Variable Browser.

Note  It is mandatory to use the Open Connection step to connect to the OPC Server before performing Read / Write operations. If the connection is not properly initiated, you will get an error 8004.

At execution, step configuration and results are added to the report.

Four variables are set in result, according to the Read operation:

       the value of the OPC variable is saved in Step.Result.ValueRead;

       the quality code of the OPC variable is saved in Step.Result.Quality;

       the quality string of the OPC variable is saved in Step.Result.QualityStr;

       the timestamp of the OPC variable is saved in Step.Result.TimeStamp;

Tip  You may configure a Post-Expression to set the read value in another variable :
Locals.NumericVariable = Step.Result.ValueRead

Caution  The OK button is disabled according to your license status (see OPC DA Connect Licensing Options):

       in Execution License;

       in Evaluation Mode, after 10 minutes since TestStand starts;

       when Evaluation Mode has expired;

 

See Also

Configuration Dialog Box

Server Browser

Variable Browser