Troubleshoot Sequencing Parameters

Verify the sequence output parameter has a valid configured expression.

Verify the sequence program has become COMPLETE, STOPPED, or ABORTED. Entering one of these states triggers the

Equipment Sequence

to automatically evaluate the expressions of its sequencing output parameters.

The sequence output parameter's InitializeAsValid flag is configured to be FALSE. Any time the sequence is initialized, the Valid flag of these tags is assigned the value of the InitializeAsValid flag.

The expression of these tags references a sequencing parameter or step tag that has its Valid flag set FALSE. When a parameter expression evaluates, the

Value

is assigned the result of the mathematical operation. The

Valid

value is then assigned the result of applying the logical AND operation to all terms having a

Valid

flag (terms of SEQ_<type> data type). If any term has its Valid attribute set FALSE, the sequencing output parameter's Valid attribute is set FALSE.

The expression on a sequencing output parameter has not evaluated yet, so the

Value

attribute's value

remains its initialized value.

The Valid attribute of sequencing outputs is not set when the tag’s Value is updated in these ways:

Check the configuration of the InitializeAsValid attribute. They may be initialized as Valid.

A control engineer or operator may have assigned a value to the sequence output parameter, with a

Usage

of read-write, which sets the Valid flag TRUE.

The control engineer or operator may have commanded the sequence output parameter to evaluate, which could set the Valid flag TRUE (all terms of SEQ_<type> data type would have to have their Valid flags set TRUE).