Sequencing parameter overview
Sequencing input parameters are the supplied values the
Equipment Sequence
requires to make product. These values are often formulation parameters (an ingredient and how much) or a processing variable (specifications of target temperature, duration, rate of speed, for example. Sequencing output parameters are reported values that record a value resulting from the execution of the
Equipment Sequence
. For example, reporting the actual amount of an ingredient used in an Equipment Sequence
.Sequencing parameters use a special data type, SEQ_<Type>.
- Value: This is the current value of the sequencing parameter or step tag. Its data type is BOOL, DINT, INT, REAL, SINT, or STRING depending on the <Type>.
- Valid: Specifies if theValueis known to be good. BOOL: 1 = Valid and 0 = Invalid.When this flag is 1, then theValuemember of the parameter or sequence is known to be correct. When it is 0, theValuemember is not known to be correct. Valid is part of Quality of Data.
- InitialValue:Equipment Sequences execute and then are returned to an initial state to be executed again. TheInitialValueis the value to be assigned to theValuemember when theEquipment Sequenceis initialized.
- InitializeAsValid: TheInitializeAsValidflag is configurable on a step output tag. On initialization, the value of this attribute is copied into theValidattribute. An initial value assigned to the step output tag can be treated as valid right away, such as in a step output parameter used as a totalizer, as opposed to a value uploaded only once when the phase completes.
- Expression: An expression may reference sequencing parameters, step tags, and local tags and local program parameters. A sequencing output parameter's expression is evaluated when the sequence enters a terminal state (ABORTED, STOPPED, or COMPLETE) and the result is stored as the value of the output.
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