[jhersh]

Thanks for the detailed write-up!

Originally Posted by John Heden

1) How do folks recommend powering the actual 2CAN device ? There are references to ensuring the Dlink radio is powered by the boosted 12V (white Wago connector) to help avoid excessive voltage drops and possible problems. The 2CAN itself has a wide voltage range (6.5 to 28V) but should it be connected on the raw 12V fused power bus? Our autonomous start is probably the worst case power consumption where we simultaneously power up 3 big CIM motors to near full power.

Powered from a 20A fused PD output.

Originally Posted by John Heden

2) Simultaneously accessing the 2CAN webpage while our robot code is simultaneously executing does result in a number of our robot CAN transactions failing (~ 1/1000). This is more of an annoyance for us than a problem but is suggestive of some type of system vulnerability when the 2CAN is being accessed from multiple sources. The WPI libraries seem to have access protection but the 2CAN itself may have some issue when it is being accessed by both the CRIO robot code and a browser on the2CAN page.

I'm not sure how this is handled in the 2CAN. Mike or Omar, can you please comment?

Originally Posted by John Heden

3) There is some mention that the FRC system does send additional CAN related messages to CAN based robots, can anybody confirm this possibility ? Could there be some type of negative interaction with the FMS system?

This is inaccurate. The FMS has no knowledge of the CAN bus. I'm not aware of anything at the application layer that would cause any interaction between CAN and FMS.

Originally Posted by John Heden

4) I did speak to a few CAN Jaguar users who spoke of possible overloading the CAN bus and needing to drop their access intervals down. The current WPI library interfaces, however, look like simple blocking calls where all access is nicely serialized and completes before the next sequence is initiated. While all of these calls may eventually slow down our control loops, it seems unlikely that we could overload the bus.

This is generally accurate. There was an issue in beta where the Jaguar token negotiation could be starved out by continuous traffic from the user application, but that was worked around.

Originally Posted by John Heden

5) We do see some type of “too much error data!” message once in a while we were playing but could not locate this error message anywhere in our code or in the WPI libraries. Any idea as to the source of this unique message?

That message comes from the error reporting to the driver station. If too many errors are generated in a short time, they won't all fit in the fixed sized packets to the driver station, and will result in that message.

Originally Posted by John Heden

6) There is a rev 66 1/29/2011 for FRC plug-in update for FRC posted on the Cross the Road website. We bagged our robot before I could confirm what version of 2CAN plug-in is incorporated in the 2/11/2011 V28 CRIO update? Is there a need for manually installing this file or is the latest included with the V28 update ?

Revision 66 of the 2CAN plug-in is included in v28.

Please let me know if you come up with any more details that might lead to the issue.

Thanks,
-Joe