Why do I get an "Incorrect data type" error or "Parameter precision loss" warning when tuning an integer or fixed-point type parameter with Simulink Real-Time & Speedgoat?

I am trying to change a Gain parameter during my Simulink Real-Time (SLRT) simulation, but I get an "Incorrect data type" error when I use the setparam target function as follows:

>> tg = slrealtime;
>> tg.setparam('MyModel/Gain','Gain',-2)
Unable to set 'Gain' parameter value on target computer 'TargetPC1': Incorrect data type.

When I try changing the parameter in the block dialog while using the external mode ("Run on Target"), I see warnings such as the following in the MATLAB prompt:

Warning: Parameter precision loss occurred for 'Gain' of 'MyModel/Gain'.  The
original value of the parameter, 1, cannot be represented exactly using the run-time data type
sfix32_En31. The value is quantized to 0.9999999995343387. Quantization error occurred with an absolute
difference of 4.656612873077393e-10 and a relative difference of 4.65661287307739e-08%.
Suggested Actions:
    • To disable this warning or error for all parameters in the model, set the 'Detect precision loss'
    option to 'none'. - Apply
    • Inspect details in the Parameter Quantization Advisor. - Open
    •  - Suppress
 
> In slrealtime/Instrument/dataAvailableFromObserverViaTarget (line 1413)
In slrealtime.Target/dataAvailableFromObserver (line 66)
In slrealtime.Instrument>@(varargin)tg.dataAvailableFromObserver(varargin{:}) (line 1332)
In slrealtime.internal.instrument.StreamingCallBack.NewData (line 25) 

Answer 1

[MathWorks Support Team]

Option 1: Use the MATLAB command line

You can first query the parameter using the getparam target function to get clarity on the data type:

>> val = tg.getparam(gcb,'Gain')
val =
  int8
   -1

In this case, you need to pass an explicit int8 Type:

>> tg.setparam('MyModel/Gain','Gain',int8(-2));

If the parameter type is fixed-point, you will see the following output for getparam:

>> val = tg.getparam(gcb,'Gain')
val = 
    -1
          DataTypeMode: Fixed-point: binary point scaling
            Signedness: Signed
            WordLength: 32
        FractionLength: 31

In this case, it is easiest to re-use the same fi object returned by getparam:

>> val.Value = -2;
>> tg.setparam('MyModel/Gain','Gain',val);

Option 2: Use SLRT Explorer

For an interactive approach, you can also check the parameter data types in the SLRT Explorer "Parameters" tab and "Type" column:

Additional notes:

1. To avoid fixed-point types for Gain parameters, enable the model setting Gain parameters inherit a built-in integer type that is lossless.
2. The Parameter Quantization Advisor app (R2022b+) may also be useful.
3. More information on controlling block parameter data types in Simulink can be found in the documentation Control Block Parameter Data Types.