Transition Logic

In addition to defining process actions and the sequence of processing, you can control (enable or inhibit) the processing of the parts of a recipe procedure based on operator decisions or process conditions, unit status, and batch information through the use of transition logic.

With transition logic, you construct a Boolean expression to be evaluated. If the expression evaluates to True, the processing of the recipe moves to the point below the transition logic. If the expression evaluates to False, the recipe processing stops and waits for the transition logic to evaluate to True.

Construct transition logic with the expression builder using the following items:

• Process Class and Instance Tags

• Transfer Class and Instance Tags

• Pre-defined Functions (Ask, Not, WaitSec, WaitMin, WaitHour)

• Constants

The following table shows all the available transition logic operators.

For detailed information on building expressions, see Chapter 16, "Expression Editor.".

Transition logic is a very powerful aid in developing a complete batching system. It is intended to be a useful tool in the coordination and processing of a recipe. It is not intended to extensively replace the functionality in the control system such as the PLC. Where you are performing Boolean expressions that are using tags in the system, there is inherent latency due to communications to the control system. Additionally, the associated processing overhead or demand placed on AVEVA Batch Management is nearly the same as that of a phase. In general, if you have in excess of 50 Boolean expressions that are using tags in the system, you should re-evaluate your system design and incorporate more of this control evaluation in the control system. The greater the number of transition objects in a system, the greater the demand that is placed on AVEVA Batch Management which may result in decreased client updates and system responsiveness.