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jbruce12000 / kiln-controller

Turns a Raspberry Pi into an inexpensive, web-enabled kiln controller.
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web clients join and temps go down #85

Closed jbruce12000 closed 2 years ago

jbruce12000 commented 2 years ago

over the course of 20s seconds or so when a new web client joins the server, something is causing the temperature read at the thermocouple to do down by 20 or more degrees. This causes the current temp to go out of the PID control window... which causes 100% heating to the kiln for that period. This causes a temperature spike in the kiln - which for me at 250F was about 10F.

Figure out the cause, put debugging on the thermocouple reads. fix it.

rondoc commented 2 years ago

Is this with a 55 or 56 board?

On Wed, May 11, 2022, 10:09 AM Jason Bruce @.***> wrote:

over the course of 20s seconds or so when a new web client joins the server, something is causing the temperature read at the thermocouple to do down by 20 or more degrees. This causes the current temp to go out of the PID control window... which causes 100% heating to the kiln for that period. This causes a temperature spike in the kiln - which for me at 250F was about 10F.

Figure out the cause, put debugging on the thermocouple reads. fix it.

— Reply to this email directly, view it on GitHub https://github.com/jbruce12000/kiln-controller/issues/85, or unsubscribe https://github.com/notifications/unsubscribe-auth/AXA65G7MT7YLL2T5GSCYK2LVJPSVDANCNFSM5VVTTJWQ . You are receiving this because you are subscribed to this thread.Message ID: @.***>

jbruce12000 commented 2 years ago

@rondoc 31855

rondoc commented 2 years ago

I am not sure but I think that my system always starts at 100% when setpoint is higher than ambient. Then overshoot is inevitable )))

On Wed, May 11, 2022, 1:09 PM Jason Bruce @.***> wrote:

@rondoc https://github.com/rondoc 31855

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jbruce12000 commented 2 years ago

The overshoot is just a side effect of the problem. The problem is that I connect a web client and the temperature read at the thermocouple goes down drastically. This issue is so I remember to track down why that happens.

jbruce12000 commented 2 years ago

renice of the kiln-controller to the highest priority has no impact. Even more drastic temperature drops happen if I do something like scp a large file from the rpi to another box. It seems like any process that takes up significant cycles may cause this problem.

jbruce12000 commented 2 years ago

this is a problem even if only a single value is read during the duty cycle. I don't think there is anything I can do about this.

captaincaden commented 2 years ago

I don't experience this issue, and when the kiln is running, I frequently have been known to exit and rejoin the server multiple times throughout a firing. I'm using the max31856 board.

jbruce12000 commented 2 years ago

this is also the first time I have experienced this issue. my guess is that it is kernel related, but I have not tried to track down the cause. since renice doesn't fix it, it's unlikely a process scheduler problem.