Driven Scan Class - Machine State

Driven scan classes set the polling rate (Fast Rate and Slow Rate) dynamically for tags based on a given condition, which is actually a logical comparison. Machine states being tied to a Boolean tag, as described below, is one example of a condition where the logic comparison is true when the machine state is ON. In simple cases, when the logic comparison is true, the Fast Rate applies, otherwise the Slow Rate applies.

To add a driven scan class based on the machine state

Lets add a driven scan class that updates the tags based on when the machine is ON.

  1. In the Scan Class Editor, create a new scan class by clicking on the green + icon on the lower-left of the window.

  2. Name the scan class, for example, you can name it Driven Machine State, and set the Mode to Driven.
    This scan class executes based on the condition you set on the Driving Tag.

  3. Click on the tag icon next to the Driving Tag box, and choose the tag you want to set the condition on.

  4. Set Operator to = and the Value to 1.

  5. Set the Slow Rate to 10,000 (10sec) and the Fast Rate to 1000 (1sec).
    When the machine is ON it will use the Fast Rate, when the machine is OFF it will use the Slow Rate.

  6. Click OK.
    Now in the Tag Browser you will see a check box next to the tag for which you have set the machine state of ON and OFF on it.