Are there any performance issues upgrading SCXI to USB?

[Dynamotive]

Hello

We have two SCXI racks circa year 2000. They form part of a soft real time control system written in C++ using Traditional Nidaq with plug in PCI Multifunction cards.

We are considering upgrading the cards to either PCI cards that support NidaqMX or NI-SCXI-1600 USB module.

1) If we use the USB module at what rate will data arrive at the host computer and be present by the callee of the NidaMX function call ? The control system requires to collected data at 10 Hz with signal latency of no more than a 50 msecs.(Please ignore windows latency)

Clearly it is very attractive to use USB over PCI since we do not have enough PCI slots available. (we are already occupying one)

2) Also will the 10 year old  racks be compatible with the NI-SCXI-1600 device?

Rack 1. Serial number AED9D7 Part Number 181455K-31

Rack 2. Serial number CEC81A Part Number 181455M-31 REV 1.0

Many thanks

Andrew

[BB.]

Hi Andrew,

Thanks for your post. The SCXI-1600 is fully compatible with your current SCXI-1001 chassis. However please note that the SCXI-1600 is only compatible with 32bit windows.

Typically PCI is a much faster bus than USB. I couldn't give you an exact figure because it would be system dependant. This Image illustrates the different bus standards both in terms of bandwidth and latency:

What kind of speeds and how many measurements do you plan to do with your SCXI chassis? We may be able to calculate the throughput of the SCXI system and figure out whats best.

Best Regards,