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Old 06-11-2011, 04:20 AM   #111
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It sounds like it should be possible to create a common file that would increment a watchdog value only if the browser was alive, and the back ground process would shutdown when watchdog value did not change. If the common file maintained a record of where you were at in the brewing process then the background process could resume operation when watchdog value begins to increment again.

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Old 06-11-2011, 04:24 AM   #112
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Oh my, those types of solutions never work out. Been there, done that, bought the video tape AND the tour package. This problem is already solved guys (see prior notes on daemon). I'm working out the JSON interface to the PHP code now...

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Old 06-11-2011, 04:26 AM   #113
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Food for further thought...not the best example since I have to physically throw a switch, which could be detected automatically, but follow me through the logic (assuming there is no automatic mode detection capability):

I have only one set of SSRs to control two separate heating elements. During the mash, I control the heating element in my steam generator. When it's time to boil, I throw a DPDT switch to use the same SSRs to control the heating element in my boil kettle.

In steam mode, I measure pressure and temperature in the steam generator, and use those inputs as the trigger to switch the element on or off.

In boil mode, I measure temperature in the boil kettle and begin to throttle back the duty cycle on the heating element as boiling temps are achieved.

I could use the browser to select boil vs steam mode without any foreseeable negative consequence. The cron job would take the mode into account when dealing with the SSRs.

By the same token, the browser could be used to dictate "off" and "automatic" modes of operation. If the cron job sees "off," it sets relay output to off and exits. Again, no negative consequences.

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Old 06-11-2011, 04:35 AM   #114
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I don't think that's a valid use case. As I've state a few times already, the task I'm working on is *not* for process control. You're outlining the process control of making a batch - and I would never use cron to control that process. It's a procedural task.

For controlling a few fermentation chambers, you can't have a cron job diddling around in the background if the user is turning things on/off via a browser control...

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Old 06-11-2011, 04:41 AM   #115
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I'm going to convince you that there is a case for browser control...even if you choose not to use it

You're on a business trip. It's time for a diacetyl rest in your lager chamber, and you realize that you planned poorly and had the lagerator set to maintain a constant cold temp. What's the harm in allowing the browser to add a time/temp to the schedule?

Yeah, yeah, yeah, you could just ssh into your machine and accomplish the same thing...assuming you have a remote client handy.

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Old 06-11-2011, 04:43 AM   #116
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Oh - we're on different pages, but agree!

What I'm working provides browser control - without screwing up the backend.

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Old 06-11-2011, 04:54 AM   #117
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Conceded.

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Old 06-11-2011, 12:03 PM   #118
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There's nothing to be conceded. I can't stay up to 2am like I used to... Geez I'm getting old (I used to code all night, going to bed at daybreak).

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Old 06-11-2011, 12:51 PM   #119
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SCORE! I just bought a CO2 monitor for $10 at a yard sale. And, it outputs voltage proportional to the CO2 ppm. As in I can put this creature in my keezer, monitor the CO2 level and make lots of noise if it detects a strong rise in CO2 levels ("Your CO2 is leaking you dummy - go fix it before it drains empty").

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Old 06-11-2011, 12:59 PM   #120
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Yuri - what did you order from Hobby Boards? The 8 channel I/O board perhaps?

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