Constraints: Setting Values (SAP Library - Variant Configuration (LO-VC))

Constraints: Setting Values

In the INFERENCES section of a constraint, you can define the characteristics for which the constraint sets values. Only enter characteristics here if you really want to use the constraint to set values. If you want to use the constraint to monitor the consistency of the configuration, leave out this section.

Note

Do not enter the characteristic variable for which values are to be inferred in the constraint condition or in an IF condition. The inference must be technically possible. This means that the relevant data fields must be defined for the table calls or function calls, arithmetical equations must allow a solution for the variable, and so on.

If you want to use formulas to infer values, you do not need to enter a separate formula for each characteristic, as is the case with some other programming languages:

Voltage = Resistance * Current
Resistance = Voltage/Current
Current = Voltage/Resistance

You only need to enter one equation in the RESTRICTIONS section of the constraint. In the INFERENCES section, you only enter the objects or variables you want to infer.

Caution

Either all the variables to be inferred or none of the variables to be inferred must be restrictable.

OBJECTS:
(300)Circuit
where V = Voltage;R = Resistance;C = Current
RESTRICTIONS:
V = R * C
INFERENCES:
V, R, I

System Performance

To improve system performance, we recommend that you only enter characteristic values to be inferred if you really need them inferred.

Table Calls

You can use tables in constraints. You can use tables to check the consistency of assigned values, to infer values, or to restrict the allowed values of a characteristic. For more information, refer to Tables in Constraints.

Why Not Explanations

If you want to see why a constraint has not inferred a value for a specific characteristic or why a specific characteristic value has not triggered a constraint, you can use the explanation facility or trace functions on the characteristic value assignment screen to find more information (see Explanation Functions for Value Assignment).