How can I read the whole input buffer of a serial port object?

31 views (last 30 days)
I am communicating with a device via rs-232 and I would like to read the whole iput buffer of the serial object at once.
What I already tried was:
s = serial('com1');
fopen(s);
fscanf(s,'%f',s.bytesavailable);
So when I run the code I only get the last value instead of the whole input buffer.
Do you have a clue what the issue could be?

Accepted Answer

Walter Roberson
Walter Roberson on 22 Jun 2015
s = serial('com1');
fopen(s);
data = char(fread(s, s.bytesavailable));
sscanf(data,'%f');
Are you certain that you want to try to read floating point text numbers when the buffer might happen to end in the middle of a number?? For text you normally want to work line-by-line (fgetl() or fgets()) or else fscanf() without a count (allowing the scanning to pause for more characters to be received)

More Answers (1)

Valentino Tomasic
Valentino Tomasic on 22 Jun 2015
Hi Walter! Firstly, I want to thank you for your fast response! Your advice worked perfectly, I could read out the whole buffer at once. My main problem is that the device sends data faster than my processing loop is (it's a real time plot). This is why the input buffer is getting filled progressively. So I thought the problem could be solved if the buffer is being read out completely.
  1 Comment
Walter Roberson
Walter Roberson on 22 Jun 2015
Is the input terminated somehow? linefeed? Or even just a comma between entries? If so then you should be programming a bytesavailablefcn callback. That callback can grab values from the serial port and store them away for a later run of the processing loop. For example you could keep a circular buffer, such as is shown blog or file exchange

Sign in to comment.

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by