Reading signed data from RS232

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VQ
VQ 2011-4-19
Hi,
I want to read 256 signed numbers from RS232. In Hyperterminal I see:
-54
-54
-54
-52
-55 . . . But when I read it in Matlab I saw something like that:
out=fread(s)
45 53 52 13 13 10 45 . . .
And if I convert "out" to char (val=char(out)) I haven't got 256 numbers, I have 45...I know that this problem is due to conversion into ASCII characters..
Can anybody give me a solution to read correctly the data?

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回答（2 个）

Chirag Gupta
Chirag Gupta 2011-4-19
Instead of using fread, try using fscanf where you can specify the format.
http://www.mathworks.com/access/helpdesk/help/techdoc/ref/serial.fscanf.html
Ankit Desai
Ankit Desai 2011-4-20
You can provide the precision that you want to use with fread.
The online documentation should provide more details.
-Ankit
  1 个评论
Walter Roberson
Walter Roberson 2011-4-20
Ankit, if you examine char([45 53 52]) you will find it is '-54' so the problem is not the precision the variables are written at, but rather that the data is being ASCII encoded and needs to be converted back to numeric form.

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