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Akash
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Reading from serial port

Asked by Akash
on 3 Feb 2011
Hi, I need to interface MATLAB with a COM port to read data from sensors. Here is my MATLAB code.
s = serial('COM5');
s.BaudRate = 115200;
fopen(s);
tic
for i = 1:25
an = fscanf(s,'%c');
end
toc
fclose(s);
I have used "tic" "toc" for measuring execution time to read 25 values and its almost 5 seconds. This is pretty slow. 115200 is the max Baud Rate.
Is there a better/faster way to read from a serial port???
Thanks all

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1 Answer

Answer by Ankit Desai on 9 Feb 2011

Akash,
You might be getting the data slowly. The delay might be caused by fscanf waiting for data to be available. As listed in the documentation - fscanf waits for data to be available until a timeout occurs.
You can confirm the same by checking that there 50 bytes available (25 bytes for character values + 25 bytes for terminator values) before you call the fscanf(s) in the for loop.
You can do so by checking the BytesAvailable field of the object.
s.BytesAvailable
I tried the same and was able to do so in < 1 second.
Hope this helps,
-Ankit

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