MATLAB: Error using SimulinkRealTime.target/getsignal

getsignalsignalsSimulink Real-Time

I have already seen the answer to a similar question without success.

I'm using Simulink Real-Time and am trying to use the getsignal command to find the current value of a signal in the model. I have successfully used this for a number of other signals with no problems but a few of the recently added signals report the error "Error using SimulinkRealTime.target/getsignal Invalid Signal".

I have tried the following

Adding a unit gain block and reading the output of that signal
Making the signal a "Test Point"
Using the Data Inspector and logging the signals (they appear in the Data Inspector but not with getsignal)

When I show the signals for the target using

tg = slrt;
tg.ShowSignals = 'on';

The signals that I am looking for do not appear in the list.

What can I do to force the signals to be visible to the host PC?

Best Answer

Found the solution.

The signal was a scalar value from a CAN Read block which was of type uint32. The normal advice to get signals to be visible is to use a Gain block with a value of 1 and this approach had worked for other signals. However in this scenario Simulink was converting the data type from uint32 to a large fixed point value (128 bits) after the Gain block.

Checking all the data types and converting the value back to a double before the unity gain block and the subsequent scaling and offset made the signal visible using getsignal.

Any data type that takes up more than 64 bits, apparently won't be visible.

Related Solutions

MATLAB: Do I receive the error “Invalid Signal” when using “getsignal” from Simulink Real Time? The signal is listed with the target properties

The SimulinkRealTime.target.getsignal function accepts either a signal ID or a Simulink Real Time (SLRT) signal name as the input. In this case, although "armed" is the name of the Simulink signal, it is considered the label of the SLRT signal. To get the signal by label, we much first access its signal ID, as follows:

sigID = tg.getsignalidsfromlabel('armed');
tg.getsignal(sigID)

More information regarding accessing SLRT signals by name can be found in the documentation.

https://www.mathworks.com/help/releases/R2017b/xpc/api/simulinkrealtime.target.getsignal.html#input_argument_signal_name

MATLAB: How to use data from a MUX block with the from xPC block in xPC Target 4.2 (R2009b)

This is due to the fact that MUX blocks are virtual blocks. So they are being removed during code generation.

To get all the signals you need to download the model to the target and connect to it. After that enter the following command in the MATLAB command window:

tg.ShowSignal = 'on'

Now you can see all signals.

If you are having a vector with two signals as input for a gain block you will see this output:

    Signals              = INDEX   VALUE             BLOCK NAME                    LABEL                         
                           0       0.000000          Gain/s1                       Gain                          
                           1       0.000000          Gain/s2                       Gain

Now you can enter these signals as a cell array in the dialog box of the From xPC block:

 {'Gain/s1', 'Gain/s2'}

Now the From xPC will extract the two signals.

Best Answer

Related Solutions

MATLAB: Do I receive the error “Invalid Signal” when using “getsignal” from Simulink Real Time? The signal is listed with the target properties

MATLAB: How to use data from a MUX block with the from xPC block in xPC Target 4.2 (R2009b)

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