Send signals through serial port without driver?

[Amanda.Ison]

Hello,

I am looking for a way to send or receive a simple high/low signal through a serial port of a computer. I know this can be done with a DAQ, but I assume there must be a way to do this via serial communication as well (for example, via a USB or RS232 port).

My application is relatively simple; I have a machine which is programmed to send a "start test" signal, wait, and then receive an "end test" signal and a binning command from a piece of test equipment (for example, an LCR meter). The signals will be a ~10ms pulsed true/low. The control functions will all be set to 5V control voltage. The interface is a 36-pin centronics port. I have a model U206-006-R "USB to IEEE Parallel Printer Cable" which I am hoping to use to convert the 4-pin USB signal to one of the 36 centronics pins. This cable is designed to use a driver to automatically communicate with the attached printer. However, since the device I am using has no "driver", there is no VISA resource name and I do not know how to send a signal to it.

Which LabVIEW functions would be appropriate for this? Are there any tips or resources you would recommend? Or is this a deceptively difficult project that I'd be better off using a DAQ for? 

Thanks,

-Amanda

[Alexander_Sobolev]

It says cable (converter) creates virtual parallel port, drivers for this converter (not of the attached device!) install automatically. Then VISA should see parallel port (LPT2 or something like that). Then you can send messages via VISA, according to your device protocol. 

Did not control parallel port lines directly, with Serial port we have used RTS line as a slow digital line. But it also required some wiring, because it is not TTL. 

[Alexander_Sobolev]

One more thing, might be helpfull

http://digital.ni.com/public.nsf/allkb/B937AC4D8664E37886257206000551CB