I am getting timeouts trying to access parallel port with VISA

[SteveChandler]

I am getting VISA timeout errors when trying to write to the parallel port. MAX says that the port is working and I should be able to communicate with it. Windows2000 device manager also says that the device is working. I am using the write to parallel port with VISA example that I found on the ni site. To make it even more confusing (or not) it works on one computer but not another. All software and drivers are identical on both machines. On the one that is giving me the timeout error, I am able to write to the parallel port using "accesshw"

[Randy_H]

Steve,

I have seen this even on my own machine. I have narrowed it down to the BIOS setting for the parallel port. I have a Dell Optiplex and it has 4 modes for the parallel port: AT, PS/2, EPP, and ECP. I can get the example to work (I also had to tie the following pins together: 1 - 13, 10 - 16, 11 - 17, and 12 - 20) under AT, PS/2, and EPP, but not ECP. On another machine in our department, ECP mode works fine. It seems to be hardware specific. I would start by looking at the BIOS setting for the parallel port on both computers and seeing if they are the same or not.

Randy Hoskin
Applications Engineer
National Instruments
http://www.ni.com/ask

[SteveChandler · Accepted solution]

What a coincidence. The computer that I was having problems with is also a Dell Optiplex. Wiring the pins together the way you specified solved my timeout problem. The cable that I had trouble with just had pins 11 and 12 tied low as specified on the page with a link to example code titled "Using VISA to Access the Parallel Port in LabVIEW" I don't know why the original cable worked with a Gateway but not a Dell Optiplex. Thanks for the quick solution!