Re: Power cycling Mark IV

[Tom Droege <tdroege@veriomail.com>]

The general plan for the Mark IV was to try to make the Stamp bullet 
proof.  It then has registers for controlling things.  Presently I am using 
one of them with a Crydom switch to turn the chiller on and off to control 
the cooling water temperature for TOM.  This is also wired up in ARNE where 
I used it to control the TEC chiller.

You can get nice switches that will run off the logic signals from the Mark 
IV registers that will control 100 HP motors.  There is no real limit.  I 
think there are 10 control signals available as built, but the auxiliary 
connector would allow unlimited expansion.

Arne can correct me, but I bet that every time so far that the stamp has 
hung, it has been due to something mechanical failing.  Usually failure to 
move to a limit.  In these cases you want to take that 90 foot walk.  Note 
that unless you are testing in the snow or rain, it is guaranteed to be a 
pleasant walk since we only run the camera when it is clear.  Might be 
pretty cold though.

The stamp code was written with the idea that it would never hang.  You can 
see the hooks there in the code.  It is just a question of implementing 
them so the stamp gives up on an operation after a reasonable number of 
tries and sends back a "failed" message.  This has been implemented in some 
but not all the cases.  I just ran out of effort but I did all the ones 
that ever gave me trouble.  I still hope for some of the rest of you to 
work on this as it is much more in your field.

The stamp code is simple.  It is not like Windows where you expect a hang 
from time to time.  When all the hooks are implemented, it should never, 
never hang.  As far as I know, there is no mystery about how the Stamp 
operates.  There is a Windows mystery.  But the stamp overcomes that.  We 
just have to finish up the stamp code.

I do not see any reason to ever reset the stamp.  I am listening for 
reasons that you would ever want to do it?

Tom Droege

At 01:15 PM 9/27/00 -0700, you wrote:


>On Wed, 27 Sep 2000, Herbert R Johnson wrote:
>
> > Date: Wed, 27 Sep 2000 15:11:09 -0400
> > From: Herbert R Johnson <hjohnson@pluto.njcc.com>
> > To: tass@listserv.wwa.com
> > Subject: Re: Power cycling Mark IV
> >
> > On Wed, 27 Sep 2000 08:47:47 -0700, Chris Albertson 
> <chris@216-178-250-236.lax1.phoenixdsl.net> wrote:
> > *>Ron, Arne,
> > *>
> > *>If what you really want is the ability to power cycle the
> > *>camera then why not simply power cycle the camera?  You
> > *>must in addition to the serial and parallel data cables
> > *>also have a power cable running outside  You could switch
> > *>the power from indoors either manually or under control of
> > *>the PC.
> > *>
> > *>Ron Wickersham wrote:
> > *>>
> > *>> Regarding reset:
> > *>>
> > *>> rather than an extra line, i could supply a module that would look for
> > *>> "break" on the serial line to reset the Stamp.  the advantage being 
> that
> > *>> if one wants to use fiber or other isolation technique then only the
> > *>> Tx and Rx lines need to be connected.
> > *>>
> > *>> is the host PC going to be moved out on the pier when everything
> > *>> is debugged as was discussed before and then just run an isolated or
> > *>> fiber ethernet for communications to improve survival from lightning?
> > *>>
> > *>> -ron
> > *>>
> > *>> On Tue, 26 Sep 2000 aah@nofs.navy.mil wrote:
> > *>>
> > *>> >  17) If the Stamp has a reset line, you might bring it back to the
> > *>> >      host computer so that you can reset the Stamp without having
> > *>> >      to run outside and cycle the power.  ----n you can cheat and
> > *>> >      use one of the serial cable handshake lines for this feature.
> >
> > There seem to be two issues, one of a reset for the Stamp, and one for
> > power cycling either the camera or the Stamp. Then there is the business
> > of a long control/data cable between the camera and the controlling 
> computer,
> > which is the current configuration. As for a "fiber ethernet", it simply
> > does not exist yet for the Mark IV.
> >
> > Frankly, I'm always spooked when I see this "long cable" business, seems
> > like a long cable is an antenna looking for noise, or a wire looking for
> > lightning-induced surges or worse. More than one of the Mark III's has
> > suffered from some kind of power damage, ask the sites.
> >
> > So the idea of a wire that would in effect LOOK for a big spike to reset
> > either the Stamp or the whole camera strikes me as a bad idea. It would
> > be a shame to mess up a camera run with a "reset" caused by a power surge.
>
>the "break" signal on an async line is not a special spike, but a
>legal signal _level_ that is longer in duration than allowed for any
>legal character, so the "break" detector would not be more susceptable
>to power surges than sending characters.
>
> > If you must have some kind of remote power cycle, try to come up with
> > something which
> > is either wireless or has some kind of protection from noise and surges.
> > For instance, a really DUMB "power cycle" is to put an AC timer on the
> > camera which briefly turns off AC at, say, 9AM when the camera is neither
> > in use nor under development. I could imagine an X10 module to do the
> > same thing, except the camera's AC supply may not be on the same AC circuit
> > as the X10 controller - X10 control codes are transmitted by the
> > AC lines. Or, I suspect most large hardware stores carry an "ac remote" 
> to turn
> > on a lamp with some kind of hand-operated RF controller. None of these 
> require
> > any software, just a shopping trip and human intervention at the computer.
>
>the present problem is to get Arne's box easier for there probably wouldn't
>be an issue if it were only a ninety foot walk to manually reset, so my
>guess is that it is a pina to reset since you can't walk directly the
>way the 90 foot cable is run.
>
>while a manual remote reset is ok for an attended site, our original specs
>called for completely unattended operation at at least some sites, so we
>can't expect an X10 in Redondo Beach to power cycle a camera on Mt. Wilson.
>but for Arne's present situation, perhaps the power supply for the Stamp
>could be controlled with an X10 module to force a reset of the Stamp.
>
>Chris' breadboard setup is closer to the ultimate configuration with only
>an ethernet umbilical to the net, so we do need to think about remote
>reset of the stamp and also the control computer.  Arne brings up the
>issue of controlling the chiller and pumps and other auxiliaries such
>as the shelter opening/closing which don't want to be cycled just to
>reset the Stamp.
>
>although you can reboot a system that is still communicating remotely,
>if the system is not communicating to the internet, then we want to
>have it at least attempt to reset after some period of time.  so we
>probably want to have some sort of heartbeat that will reboot after
>say 15 minutes of no pings being answered, or if you think you want
>it to at least complete a nights' run if isolated, then reboot after
>x hours.
>
>while this is probably going to be different for each site it is worth
>thinking about.  should an unattended site reboot each day with a
>timer?  or is the heartbeat a better solution?
>
> > If a reset is to be sent over this 90-foot cable, some circuits
> > should be added to make sure the command must be a long pulse rather than
> > just any old "spike".
> >
> > Herb Johnson
>
>-ron