Wrong type and signal class for ExternalInterface "Y" on "InputParameter" creates conflict with non-analogue constants definitions (eg, boolean TRUE/FALSE)

[Erik0x42]

Problem

InputParameter's terminal "Y" is of type "AnalogueOut" and has SignalClass restricted to "Analogue".
InputParameter may be boolean (eg, "TRUE") - this is defined by the wording "logical operands" in the standard.
The current implementation in NorsokSCDLibrary.aml will cause a conflict between terminal type/class and binary values.

XML with issue comments:

<SystemUnitClass Name="InputParameter" RefBaseClassPath="ElementaryFunctionLibrary/NorsokElementaryFunctionClass">
  <Description>process parameters, numbers and logical operands </Description>
  <Attribute Name="Parameter" AttributeDataType="xs:decimal">
    <Description />
    <DefaultValue />
    <Value />
  </Attribute>
  <ExternalInterface Name="Y" RefBaseClassPath="InterfaceClassLibrary/NorsokSignalClass/Out/AnalogueOut" ID="6b2117e3-8475-7e4b-9309-fed0ce98bac7">
    <!-- hidden lines  -->                                                                  ^^ wrong ^^
    <Attribute Name="SignalClass" AttributeDataType="xs:string">
      <Description />
      <DefaultValue />
      <Value>Analogue</Value>
      <Constraint Name="LegalValues">
        <NominalScaledType>
          <RequiredValue>Analogue</RequiredValue>    --   this is wrong (remove restriction)
        </NominalScaledType>
      </Constraint>
    </Attribute>

Proposed solution

1. Change terminal "Y" type (RefBaseClassPath) to "Out" (one level higher in the interface class hierarchy)
2. Allow also Binary as SignalClass

Applying these two fixes will align this output terminal with similarly data type agnostic terminals of Split, Opt and BlackBox.

References

• IEC PAS 63131:2017 Figure B.12 - Fixed parameter label
• IEC PAS 63131:2017 Table D.8 - Constant values

[cdenisey]

It is preferable to maintain same Terminal Y already established so as to disturb less SCD tools already established, Therefore suggestion to also allow Binary definition should be adopted. However, the "Parameter" attribute allows for AML export to correct values (Analogue or Bolean), so there should be alignment between them upon export.