2012 Field Comm. Issue Logs

[Greg McKaskle]

A couple things that may help with reading the logs.

1. A spike at the beginning of auto is an glitch in the measurement. The DS was modified to zero the lost packets when the match begins. As a result, the delta loss reported into the logs will sometimes show a high spike at the very beginning of auto. You cannot trust this point.

2. If the communication with the robot fails, the voltage will disappear, and other lines such as CPU should be flat and cached. Lost packets and trip time will often look high for a time when a drop occurs.

3. The lost packets numbers is typically "out of 25". So 10 lost packets over half second means 10 out of 25 were lost. If communications is lost entirely, the timeout is 1 second, so the number may go above 25 and be "out of 50".

4. When packets are lost, it is common for CPU to drop. The code for tele and disabled are typically waiting for new DS packet, so less to do when less packets comes in.

5. If the DS line suddenly shows a disabled line, but the robot line seems to ignore it, this indicates a watchdog due to communications drop. This means the robot outputs were disabled due to more than 5 consecutive packets not arriving. Note that it is possible for occasional packet arrival to keep the robot enabled, and this is typical.

6. If you see periodic spikes in the trip time and/or the lost packets, this may very well be due to the DS. If you observe these when cabled, that is supporting evidence that something on the DS is a likely cause. Opening the Task Manager may show a process bumping to the top in time with the blip.

7. Trip time doesn't necessarily mean latency. The trip time includes the trip to the robot and back again. If delayed to the robot, it impacts driving. If delayed on the robot or on the return trip, or often within the DS laptop, the trip delay does't imply that the robot is hard to drive due to lag.

8. Similarly, lost packets may make it to the robot and keep the watchdog alive and be lost on the return trip.

Greg McKaskle