Juan,
You say it jumps when you start the heartbeat. Are the jumps at the same frequency as the heartbeat? Are you at a 5Hz poll (for instance) and are the jumps then 5 times a second? This would indicate that something in the configure message is causing the jumps.
You suggest that it might be the 3 Sec. watchdog but that doesn't make sense if the heartbeat is actually running unless the heartbeat is not communicating with your device... The widget watchdog will not fire if a configure message for the widget is heard by the widget within the 3 Sec window.
(I can't tell from your writup what's happening so I'm trying to clarify...)
If you see this happen again you can save the CAN traffic log and send it to me. I might be able to see something in the traffic.
I've been lurking and enjoying reading all of your reports. You've been doing great work.
I'll be glad to help where I can.
Regards, Stephen --