[Tutor] how to read over serial port

[bob gailer]

shawn bright wrote:
> Hey there all,
>
> I have a gps device that talks to the computer over a serial port.
> i am using the pyserial module and getting values in.
>
> Here is my delima,
>
> i am supposed to read a message in that starts with a $ (this is all ascii).
> but when i do a ser.read(16) and i try to print it to a screen, it is
> all just weird characters.
>   

I did not realize there was a Weird character set. I'd have expected 
ASCII characters. (chuckle?)

When you say "weird" I guess you mean unexpected. What exactly did you 
get and what exactly did you expect?

> i had it write each byte to a file  like
> f = open('test', 'wb')
> msg = ser.read(16)
> for i in msg:
>     f.write(i)
> f.close()
>
> then when i open it with python and do
> f = open('test', 'rb')
> and read it it is the same weird characters.
>   

Well of course. Writing to a file and then reading it should give the 
same results. Again what did you expect and why does this surprise you?

> when i add a line to print the type after reading like this:
> for i in msg:
>     print str(type(i))
>
> i consistantly get type str
>   
That's good. It tells us that msg is a character string.
> so, what am i supposed to be doing to get real values out of this
> stream of bytes?
>   

Depends again on what you are expecting. What do you mean by "real"?


-- 
Bob Gailer
Chapel Hill NC 
919-636-4239

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