I have connected a transistor circuit to my parallel port.I want to operate on it.
Basically i will set voltage and current from outside source and will take the values of voltage and current as input from parallel port(I have done everything regarding the hardware part and have difficulty in c programming)and using that values i want to plot the curves(current vs voltage).
How can i do that using c program?(taking the input from parallel port and plotting the curves)?

I'm not an electrical engineer, so I might not fully answer your Q.

I'm using VC++, under Help, I found:
_inp (read one byte from specified I/O port)
_inpd(same as _inp but double word)
_inpw(2 byte)
_outp(for write)
_outpd
_outpw

I searched from Google, Parallelport programming, and found this:
http://www.lvr.com/jansfaq.htm

Be carefull with your wiring to Parallelport pin, you might hose your motherboard or Input card.


cheers,
  Johan

  Also, from UNIX / Linux and variants, you can open a file under your /dev directory and write to it like a normal file. for examplte /dev/lpr or /dev/ttyS0 ... /dev/ttyS<n-1>

Regards,
Meredith Shaebanyan