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Unread 11-05-2012, 09:48
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Re: Intermittent connection on field only

Quote:
Originally Posted by Alan Anderson View Post
There actually is a possible reason for CAN errors to shut off the compressor. It's a second-order effect. The error processing and reporting uses up a lot of system resources, delaying other actions, including the communication task. The system watchdog times out because the data from the Driver Station didn't get processed in time. Every PWM and Relay output on the Digital Sidecar gets shut off. Since the compressor is controlled by a Spike relay, it stops.

Alan,

Great analysis. What I'm trying to figure out is how we've advanced, if when we used C, we would be careful about interrupt priorities so that critical functions (i.e. packet transmission) were not delayed. When I use Labview, I run sensors and actuators in separate vi's, not in the main case structure. I know that if I'm not careful, a separate process can eat up resources as well, but doesn't Labview allow you to prioritize specific processes? Could we then not protect comms? Of course, careless programming might have the robot stop because of the causes you outlined. But the comms would stay up.
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