The NF does not recognize a discrete variable as such

[Francesco Casella]

Please check ​Modelica.Electrical.PowerConverters.Examples.DCAC.MultiPhaseTwoLevel.MultiPhaseTwoLevel_R.err. The following error is reported:

[Modelica 3.2.2/Blocks/Discrete.mo:68:5-68:21:writable]
Error: Argument 1 of pre must be a discrete expression,
but signalPWM.zeroOrderHold.ySample is continuous.

The source code reads:

  block ZeroOrderHold "Zero order hold of a sampled-data system"
    extends Interfaces.DiscreteSISO;
    output Real ySample(start=0, fixed=true);

  equation
    when {sampleTrigger, initial()} then
      ySample = u;
    end when;
    /* Define y=ySample with an infinitesimal delay to break potential
       algebraic loops if both the continuous and the discrete part have
       direct feedthrough
    */
    y = pre(ySample);

  end ZeroOrderHold;

From Section 3.8.3 of the Modelica Specification

Discrete time expressions are:
Discrete-time variables, i.e., Integer , Boolean , String variables and enumeration variables, as well as Real variables assigned in when-clauses

In this case, ySample is assigned in a when-clause, so it is discrete-time, not continuous-time.

[Per Östlund]

Fixed in 6f42885.