raspberry pi串口问题

Question

I'm using raspberry pi 2 to control 2 types of printers. I found at this site how to send serial commands in hexadecimal format using python, like:

cmdTest=b"\x12\x02\x42"
ser.write(cmdTest)

This code works true for one printer but fail for another! knowing that:

I test both devices using a normal computer and both works.

Both are from same manufacturer (ELTRA SISTEMI ).

I am using the appropriate commands for every printer

I am specifying the correct baud rate knowing that both are of the same baud rate.

Answer 1

My problem solved, Although something still not clear. The commands were correct the problem is something related to the serial convertor I were using. Now I used a usb to serial convertor instead of a shield convertor and it works great with same code and same commands. Although it worked, I'm still confused why a printer worked with RS232 shield and other not.