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Unread 15-03-2011, 20:32
jhersh jhersh is offline
National Instruments
AKA: Joe Hershberger
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Re: A different Serial CAN problem.

Quote:
Originally Posted by PhilBot View Post
The problem is that this "0.0 postion" error persisted for many reboots, debug download etc. and then just returned to normal and hour later.
Sounds like you had a short between the wiper and ground on your pot.

Quote:
Originally Posted by PhilBot View Post
The Jags are switched between "Voltage out" and "Position mode" each time a preset recall button is pressed (and held). Before the new mode parameters are loaded, the JAGs are disabled, and then re-enabled at the end. All of the JAG parameters (control mode, position source, pot turns, PI gains etc) are re-loaded, and the code checks for any errors and re-tries the command sequence 3 times if errors persist.

Note: We'd run into the occasional bad-command-write problem several days before shipping and had built in the retries. So it's pretty bullet proof.
Sounds like a nice implementation. We did something similar last year and had no problems like this. The main difference between our setup and yours is we were using an encoder instead of a pot.

Quote:
Originally Posted by PhilBot View Post
Do you think accidentally sending the JAG an invalid "position value" (eg: a negative value for target position) could lock up the controller????
I don't think it should matter, though I can't say I've explicitly tested for that. If you can reproduce it with a simple program, let me know.

-Joe
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