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How can I create byte values from integers in Python?

Background: I need to send a numerical value as a byte to an external device, but I have run into a problem. My code is:

ser=serial.Serial("COM3",9600, timeout=0)
ser.write(value)

where "value" is an int that I read have read. The problem is, when I send this, it sends the character value, not the actual value (it sends the byte value 31 for the number 5, since that is the unicode position for it, I believe)

In reality, I want to be able to send it the character "\x05" for example. I guess my question is, how would I convert and int 5 to a char "\x05", or 37 to "\x37"

like image 922
mattdee123 Avatar asked Dec 13 '22 04:12

mattdee123


2 Answers

Use the built-in function chr().

If you have a list of such integers you need to send, you might consider using a bytearray().

Alternatively, in newer versions of Python you can simply use a byte type.

like image 70
Amber Avatar answered Dec 28 '22 07:12

Amber


you can use this..

bytes(chr(my_int))    # not strictly correct unless 0<=my_int<=255
bytes((my_int,))
like image 45
shofee Avatar answered Dec 28 '22 06:12

shofee