Communication Trouble

[mbram]

We are having trouble communicating with our robot. We can achieve communication and run code however after running for 3-4 seconds we lose both communication and code. We've checked our undercarriage and found no problems. We've tried from different computers and we have also reset everything several times. Does anyone here know what may be the problem?

[MagiChau]

Check the power connection of your cRIO. The cRIO could be restarting itself if there is nothing else wrong.

[mbram]

Alright, we'll do that right now, thanks.

[jee7s]

In the event the power connection isn't the cause...

This also sounds like it could be a watchdog expiration problem. Are you sure you are feeding the watchdog in your program?

[Jon Stratis]

A few other places to check...

Check the entire power path from the battery to the cRio. There should be no "wiggle" in any of the connections - the battery terminals, the terminals on the 120A breaker, or the terminals on the power distribution board. If any of those spots is loose, it can cause a high resistance which will reduce the power available to the robot, possible causing a cRio reset.

Also check your electrical isolation. The cRio should be completely isolated from the frame, as the case for the cRio is grounded. I've seen scenarios where the cRio appeared isolated when the robot was sitting there, but when moving it would bounce around a little bit, or the material it was mounted to would flex, and it would short to the frame. If anything else is shorted to your frame (like a 775 from last year, or a wire someone accidentally caught under the head of a bolt), you can cause power issues that will cause a reset.

[DavidGitz]

Originally Posted by jee7s

In the event the power connection isn't the cause...

This also sounds like it could be a watchdog expiration problem. Are you sure you are feeding the watchdog in your program?

Unless you have a specific need for it, there should be no reason to feed the watchdog in your code. This necessity was removed last year and now this is taken care of by the WPI Library functions themselves. This is true for Labview but I'm not sure of other programming languages (but I bet it is).

Can you describe the exact situation of how you lose communication? Does it happen after driving/moving the robot? Do you ever get to enable the robot? Does it happen when you Download and/or Deploy? Do you get any messages on the Diagnostics panel? Does it happen on wireless and wired connections? After this happens are you still able to ping the cRIO and/or the radio?

I'm not 100% sure here, but I think that if you are getting the "No Communications" red light that means your radio has lost connection, and should be independent of the cRIO (i.e. not a power connection problem on the cRIO).