Convert : hexadecimal string to decimal integer with Python

Question

I am new Python user and I am trying to convert hexadecimal string to decimal integer with Python. In my system, I send analogue values like :

import serial 
import binascii 

ser = serial.Serial(port = 'COM3',
    baudrate = 9600,
    bytesize=8,
    parity='N',
    stopbits=1,
    timeout =None) # my parameter to communicate with my card
ser.open() 
a = binascii.a2b_hex('010f0001000000c8d9') # transform hexadecimal under binary format (no problem)
u = ser.write(a) # send binary data (no problem, it works fine)
i = ser.read(u) # read the answer 
i 
# I get that hexadecimal string : '\x02\x01d\x0f\x00\x00\x02\xbf7'

What I tried :

int(i, 0)

it did not work,and I did not find anywhere how I can translate that into a decimal. Does someone know?

I think you need to check what you are receiving is correct from your serial port... — Iron Fist, Dec 04 '15 at 11:22
Also, Check that you are setting up the correct parameters for the Serial protocol .. baudrate, bytesize, parity..etc...This can receiving non-formatted data... — Iron Fist, Dec 04 '15 at 11:32
The output for i is composed with smileys and all. I checked the parameters they are correct. :) — Dianou, Dec 04 '15 at 15:03
@Dianou seems you are having good Chat with your device ... :) — Iron Fist, Dec 04 '15 at 20:34
Possible duplicate of [Convert hex string to int in Python](https://stackoverflow.com/questions/209513/convert-hex-string-to-int-in-python) — betontalpfa, Apr 01 '19 at 14:47

score 0 · Answer 1 · answered Dec 04 '15 at 11:35

0

You are getting the binary representation in i. To keep with the logic of your program you can use binascii.b2a_hex to convert it to a string of hex digits, and then use int(string,16) to convert it to a decimal int.

b = binascii.b2a_hex(i)
number = int(b,16)

Mind you, it's going to be a long int, so handle it with care

answered Dec 04 '15 at 11:35

Noel Segura Meraz

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That does not match what is sent – Padraic Cunningham Dec 04 '15 at 11:41
As I understand it doesn't need to. They program just sends a value, and the card in the other end responds with a different value of the same size – Noel Segura Meraz Dec 04 '15 at 11:43
@PadraicCunningham, Does it have to be the same?...Because it's communicating with another device...not looping, unless OP confirms it to be so... – Iron Fist Dec 04 '15 at 11:49
In that case there is no need for binascii at all. Int.from_bytes will do – Padraic Cunningham Dec 04 '15 at 11:49

Convert : hexadecimal string to decimal integer with Python

1 Answers1