Testing parallel port loop device
 

Hi,

I've soldered a parallel port loopback device and want to test it. I tried simple command:
echo hello > /dev/lp0 but it doesn't respond. Can it be done in this way or is there is another way?

Thanks
Indy

I assume that you are writing to the port via echo and reading the response via the cat command similar to the serial port. The parallel port loop back plug works differently then the serial port loop back. You would set an output data pin high and then check the corresponding input pin to see if it was high. Since not all of the data pins are used sending characters via the echo command will not work.

In the old days I had Norton diagnostics (dos/windows) but I have not used it in many years. It would be easy to write your own c program.

thanks, I thought so. I'll get a utility to test it.

Thanks,
Indy