[Justin Buist]

I ran into something similar last year trying to pair an Arduinio up to our RoboRIO to use inexpensive sensors meant for Arduino. I never did figure it out but only spent an hour on it.

Reading this thread jogged some stuff loose. VISA is a serial protocol standard of sorts that I've dealt with a few times writing software for credit/debit card PIN pads. It's kind of a shot in the dark but have the Arduino shoot back an ACK byte (0x06) after it receives its command. That might make the NI code on the RoboRIO happy.

Given that I'm not the only one confounded by the WPILib serial implementation I suspect they're adding VISA rules in there but not documenting them well. It'd be nice if we had something like rxtx available but that does not appear to be easy.