Is usb interface suitable with realtime control?

[necromancer]

what is advantage and disadvantage of realtime control via usb interface

 

[checkmate]

It really depends on how strict your real time requirement is. If it's real strict, even if usb is fast enough, windows and non-RT linux are not real-time operating systems by themselves.
In terms of data acquisition rate, I would say that the bottleneck lies more in the ADC used, and maybe even more on the microcontroller overheads, rather than the data transfer rate for usb2.0.
Furthermore, USB is a shared bus system, though there are transfer modes that can reserve most of the bandwidth for a single device.
For applications requiring high-speed data acquisition, nothing still beats a DAQ card, with no uC delays and direct interface onto the PCI bus.

 

[bamdad]

as far as the standard is concerned, USB architecture inflicts a maximum delay of 1millisec on any data transaction, which is not deterministic. and another point is that the USB HOST controller is responsible for ALL data transactions, even the INTERRUPTs, so it might not be so suitable for any "real time" application, depending on how "REAL" the time must be.

 

[Niver]

I think that at least it is usefull for demo purposes in integrated environments. I wonder if you can create an USB I/O card and compute control algorithms of 10 ms or more in the Host...perhaps linking the card with xPC Target in Simulink.

Moreover....10 ms of Time Step is enough for almost any control application. You could run your MegaRobustPredictive controller in the Host and manage I/O through USB.

Added after 2 minutes:

I think that, at least, it is usefull for demo purposes in integrated environments. I wonder if you can create an USB I/O card and compute control algorithms of 10 ms or more in the Host...perhaps linking the card with xPC Target in Simulink.

Moreover....10 ms of Time Step is enough for almost any control application. You could run your MegaRobustPredictive controller in the Host and manage I/O through USB.