[Greg McKaskle]

Tom, the shipping company has graciously volunteered to do that testing.

Austin, I was going to send you a URL to the specs, but what I could find was pretty light. I'll try to answer them here.

USB bus can be overloaded, but so can ethernet. The effects when you do so are different, and you are correct in being skeptical. It will be tested in this situation.

As for other I/O rates -- the roboRIO is a similar architecture to the cRIO and all other NI RIO devices. RIO stands for Reconfigurable I/O, and that means an FPGA is user-programmable to handle the hard-real-time duties like building a decoder from some digital inputs. The I/O speeds of cRIO are determined by the modules, so the roboRIO digital speeds are actually far higher.

I don't have the details on count and speed, but it I believe it is the same number of encoders at about 10x the speed.

As for jitter of the RT code reading the encoder, that is something you control. VxWorks is a realtime OS and you should be able to measure and control jitter, but the base templates and frameworks in FRC avoid many of those features in order to keep the code clean. The RT-linux OS will offer many of the same features, but if you don't use them, you are trading simpler code for jitter. How much jitter are we talking about, and do you know what was causing it?

Greg McKaskle