how to control time sequence for handshaking

[phlins]

Hi all,

  I am reading some material about using VISA to control the data input/output to external device (in serial or parallel port). For some device, it needs a precise time sequence for handshaking to 30 nanosecond, I wonder if it is possible to control from OS level to make such short time interval? I am using Labview 2011 and Windows7 32 bits

[Tortu]

Greetings phlins

In general, software time operations in Windows won't go beyond 1ms. Even if you use an RT OS, accuracy won't go further than micro seconds. Only FPGA or hardware timed tasks can handle nanoseconds. This is regarding digital operations in general.

You may want to check this document:

http://digital.ni.com/public.nsf/allkb/D37754FFA24F7C3F86256706005B9BE7

It talks about the supported baud rates for NI-VISA. With this, just make the conversión to the actual time each baud rate handles and compare it to your requirements.

Finally, when you said this handshaking is for a device, have you considered searching for a device driver? There are many device drivers available for LabVIEW, if i may ask, wich external device are we talking about?