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<== Date ==> <== Thread ==>

Subject: Re: wdTimer & EPICS sequencer
From: Andrew Johnson <anj@aps.anl.gov>
To: rjpage@mit.edu
Cc: Tech_Talk <tech-talk@aps.anl.gov>
Date: Sat, 30 Jan 1999 11:15:50 -0600
"Russell J. Page, Sr." wrote:
> 
> I'm presently trying to resolve a problem in an EPICS Sequencer Program.
> I need to create a delay and the SNL delay function is unsuitable for
> what I need to do. 

It would help if you explain a little more about what you actually want to
occur and why the SNL delay function can't do what you want.  I'm not sure
a watchdog timer would be your best solution, but without understanding
the problem it's hard to suggest alternatives (eg would calling taskDelay
in an action statement solve this?).

> Using the escape mechanism with a usr function, I am
> able to create a vxWorks watchdog timer okay, but when the timer
> expires, I need to return to the sequencer code. At present, my test
> timer returns a message to my debug terminal as I expect (I use the
> printf function). I tried every permutation I can think of on the idea
> of exit(), wdDelete, wdCancel, etc. but all that happens is either a
> reboot of the target or the terminal hangs. ^C, ^Z etc. won't break it.

The watchdog callback function is executed within ISR context; you can get
all kinds of crashes if you're not careful here.  Check the vxWorks users
manual for information on what is & is not allowed.

- Andrew
-- 
New country, job, address, car and signature; same old Andrew Johnson

References:
wdTimer & EPICS sequencer Russell J. Page, Sr.

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