python sending a hex string to serial port

Question

I am trying to send a hexadecimal string to a serial port and it has to be in the following format '\x02\x81....' this is my code

from binascii import unhexlify
string='0281E1B1'
print unhexlify(string)

gives me some randon symbols ?a+ instead of \x02\x81\xE1\xB1 I have python 2.7 so decode('hex') isnt working either

Joran Beasley · Accepted Answer · 2015-05-08 16:29:15Z

3

you are doing it right .... you just need to send it over the port

print repr(unhexlify(my_string))

my_serial.write(unhexlify(my_string))

#or 

my_serial.write(my_string.decode("hex"))

the problem is you cant just print random bytes( "\x##") to the terminal and expect to see something that makes sense ...the terminal displays characters it cannot decode a ? or like a diamond with a question mark

>>> '0281E1B1'.decode("hex")
'\x02\x81\xe1\xb1'
>>> print '0281E1B1'.decode("hex")
☻üß▒
>>> '0281E1B1'.decode("hex") == unhexlify('0281E1B1')
True

although for whatever weird reason my terminal didnt add any ? to that particular string

edited May 8, 2015 at 16:29

answered May 8, 2015 at 16:24

Joran Beasley

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1 Comment

Mariam H Over a year ago

Thanks for explaining! You are right it all works now :)

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