Error when trying to read data from serialport

Hello!

I have a serialport connected, like this:

s = 
Serialport with properties:

                 Port: "COM9"
             BaudRate: 115200
    NumBytesAvailable: 950

The data I gather from here looks like this:

>> readline(s)

ans = 

    "*RRN:00000000C76D,00000000C6F1,0,000651,0004,-59"

This device is receiving that kind of data every second or so (it´s not fixed). So "NumBytesAvailable" increases every time (I believe it is 50 Bytes every line). I want to read every of these lines, every time there is a new one. But I don´t know how to use "Callback".

When Callback is on, I have these error (increasing errors every time there is new data in terminator)

    >> configureCallback(s,"terminator",@callbackFcn)
Warning: Error occurred while executing the listener callback for event DataWritten defined for class asyncio.InputStream:
Undefined function 'callbackFcn' for input arguments of type 'internal.Serialport'.

Error in internal.Serialport/callbackFunction (line 1353)
            obj.BytesAvailableFcn(obj, dataAvailableInfo);

Error in internal.Serialport>@(varargin)obj.callbackFunction(varargin{:}) (line 958)
                        obj.StringClient.StringReadFcn = @obj.callbackFunction;

Error in matlabshared.transportclients.internal.StringClient.StringClient/DataAvailableCallback

Error in matlabshared.transportclients.internal.StringClient.StringClient>@(varargin)obj.DataAvailableCallback(varargin{:})

Error in matlabshared.seriallib.internal.Serial/onDataReceived

Error in matlabshared.seriallib.internal.Serial>@(varargin)obj.onDataReceived(varargin{:})

Error in asyncio.Channel/onDataReceived (line 487)
                notify(obj.InputStream, 'DataWritten', ...

Error in asyncio.Channel>@(source,data)obj.onDataReceived() (line 425)
                                         @(source, data) obj.onDataReceived()); 
> In asyncio/Channel/onDataReceived (line 487)
In asyncio.Channel>@(source,data)obj.onDataReceived() (line 425) 
Warning: Error occurred while executing the listener callback for event DataWritten defined for class asyncio.InputStream:
Undefined function 'callbackFcn' for input arguments of type 'internal.Serialport'.

Error in internal.Serialport/callbackFunction (line 1353)
            obj.BytesAvailableFcn(obj, dataAvailableInfo);

Error in internal.Serialport>@(varargin)obj.callbackFunction(varargin{:}) (line 958)
                        obj.StringClient.StringReadFcn = @obj.callbackFunction;

Error in matlabshared.transportclients.internal.StringClient.StringClient/DataAvailableCallback

Error in matlabshared.transportclients.internal.StringClient.StringClient>@(varargin)obj.DataAvailableCallback(varargin{:})

Error in matlabshared.seriallib.internal.Serial/onDataReceived

Error in matlabshared.seriallib.internal.Serial>@(varargin)obj.onDataReceived(varargin{:})

Error in asyncio.Channel/onDataReceived (line 487)
                notify(obj.InputStream, 'DataWritten', ...

Any help please? Thank you in advance

[Sebastian Bomberg]

Hi Javier,

it looks like the callback function "callbackFcn" does not exist or is not on the path. Perhaps you just copied parts of code from a generic example?

Have a look at this example in the documentation

Use Callbacks for Serial Port Communication

You will find the actual body of a callback function that reads and displays one line of data whenever a terminator is read.

Hope this helps

Sebastian

[Javier Mateo]

Hi Sebastian, thank you very much again for your support.

I tried the function, but I am missing something or I do not know how to use it... I have never played with functions

(using "serialport" instead of src, does not work neither)

This is what I got:

[Sebastian Bomberg]

Javier,

please save your above function to a file readSerialData.m and have a look at the rest of the steps in the example:

• Create an instrument object — Create the serial port object s associated with serial port COM1.

        s = serialport("COM1",9600);

• Configure properties — Configure s to execute the callback function readSerialData when the terminator is read.

        configureCallback(s,"terminator",@readSerialData)

• Disconnect and clean up — Clear the objects from the MATLAB® workspace when you are done.

        clear s

[Javier Mateo]

Yes, it worked flawlessly, thank you!

I can get the data in the command window. However, my goal is to play with this data and plot it in real time.

Could you please help me with that? I dont see the variable "data" in the workspace. I don´t know how to play with this data then

If I try to write any code below the readSerialData.m code, the callback terminator does not work anymore

[Samuel Olufemi Taiwo]

you have to create whatver you want to plot within the function.