Is there an equivalent serialbreak() function with the new serialport class in MATLAB 2020b?

MATLAB is recommending the switch to serialport as opposed to serial. With the old serial class, you could send a serialbreak() command. With the new serialport() class, I cannot locate a similar functionality. Is there a way to do this? Thanks.

------------------------------------------------------------------------------------

% Old way.

mbed = serial('COM9');

fopen(mbed);

serialbreak(mbed,1);

% New way.

mbed = serialport('COM9',9600);

% How do I send serial break with this new class?

Answer 1

[Pratyush Roy]

Hi Matthew,

As of MATLAB R2019b there is no builtin function to send a serial break to the 'serialport' object. Instead this will have to be done manually by sending 0 bits to the device for a certain amount of time, depending on the device. For example you can manually write 0s for the necessary amount of time:

write(s,zeros(1,amount),"uint8")

Hope this helps !!

[Walter Roberson]

NO this will not work!! Every byte written this way will be properly framed with start and stop bits, and it will just be data transfer!

break is holding the line at 0 V for more than one character time including start and stop bits. This is not a possible character: any possible character would switch to mark within that time.

https://stackoverflow.com/questions/1279478/rs-232-break-signal

That has a suggestion that I had long forgotten. Switch to a much lower baud rate, preferably at least 10 times slower. Send 0. This will hold the bits beyond the time expected by the receiver.

Note that this technique might have problems if the receiver is in autobaud.

[Mike Kokko]

Has this been addressed yet? I'm trying to transition from serial to serialport and this is a show stopper. The baud rate trick doesn't seem to be working.

[Mike Kokko]

@Pratyush Roy do you know if there is a fix yet for transitioning serialbreak() to the new serialport interface? I need to send an actual serial break to a device (not just framed packets of zeros) and am concerned that we will lose this capability when the serial interface is removed from MATLAB. Thanks.

[Walter Roberson]

Mike Koko:

You will need to raise this as a technical support case to emphasize to Mathworks that it is needed.

The new interface is, in my opinion, not currently suitable for controlling a serial port.

There was a time when I wrote modem control software, and data transfer software over dialup. I was a systems administrator for an ISP with international nodes. The current serialport() interface would not be usable for that kind of purpose.

[Mike Kokko]

@Walter Roberson Thank you very much, I will do that.

Answer 2

[Michael]

This issue has been fixed in R2023b: https://www.mathworks.com/help/matlab/ref/serialport.serialbreak.html