NI-PCI 8431

[alex62]

Thanks

[alex62]

Hi,

Can  help me  a Synchronous VISA Function ?

What do you  think?

Thanks.

[Dennis_Knutson]

No, that has nothing at all to do with your issue.

What sort of testing are you doing that the time between writes is so critical?

[alex62]

My application must response to every command (16 bytes frame) with frequency 200Hz without  skipping of command streem.

[crossrulz]

If you have that tight of a timing requirement, then you really should go to an RT system and/or FPGA.  Even then, it will be pretty close, even with 115.2kbaud (10 bits/byte*16bytes/155200 = 1.4ms, 200Hz = 5ms).

[Dennis_Knutson]

Your application that is receiving the data must respond in a deterministic manner? Then your LabVIEW code should be the same.

[alex62]

What do u mean "the same"?

I have to check my application for stream of command with freq. 200Hz(the freq. have to be constant, no gaps) and I have to response to each 200 Hz command.

I really must use RT system...

[cody_a]

I think Dennis_Knutson's point is that if your application has tight timing requirements, your software must be deterministic, and therefore requires a RT operating system.  The inherent jitter introduced by a non-RTOS such as Windows will not allow you to achieve the strict timing requirements your application seems to have.

If you must receive and respond to commands at 200 Hz without jitter, you really should use an RT system.

[Dennis_Knutson]

Whatever sort of widget you have connected to the serial port would appear to be designed for a non-windows environment with the custom baud rate and tight timing requirements. If you don't think that requires an rtos at the other end, you have completely misunderstood or misrepresented the widget.

There have been enough comments on the need for an rtos and the thread has been marked as solved.