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[jbruce]

Hi Auber folks,

I built a kiln controller for my old kiln-sitter skutt kiln.  It uses a SYL-2352P at the heart controlling a 50A SSR which controls whether the 220V elements are on in the kiln.  The SYL-2352P works as advertised and described in the manual.  I have done auto tuning at 1000F and variance at the temperature is just a few degrees - which is great.  If I use the same settings at 200F, the variance is 45 degrees.  It goes about 5 degrees below 200 and then 40 above.  All this makes sense because auto tuning was done at 1000F.

I think a great feature would be to define several temperatures (maybe 3) where you can supply P,I and D values and it would use those values as the kiln heats up.

An even better feature would be for this to happen as what I'm gonna call Awesome Auto Tune.  Awesome Auto Tune would go something like this:

1. heat up the kiln to 300 degrees and hold
2. auto tune at 300 degrees, record the pid values
3. heat up the kiln to 600 degrees and hold
4. auto tune at 600 degrees, record the pid values
5. heat up the kiln to 900 degrees and hold
6. auto tune at 900 degrees, record the pid values

so on an so forth up to 2300F. 

Later, when you go to use the kiln and controller, you program your ramps and holds as normal.  These pid values would be automatically changed to match the nearest temperature.  This way, you get much lower temperature swings across the entire temperature range of your kiln.

[Kkane]

Thanks for your suggestion. Some information for you:

1. Auto-tune is the process to calculate the best PID settings based on your current set temperature. It is only for calculation, and you cannot use it for normal operation. So after auto-tune is done, you will have a very good control at your current set temperature. For other set temperatures, the control result could be less perfect. That is the reason why we recommend to run auto-tune at your most important set temperature in your whole program.

2. If you want perfect control, theoretically you need to adjust PID settings for different set temperatures. And you need to run auto-tune multiple times for different set temperature to obtain those PID settings. Currently this controller can only store/use one group of PID settings. You have to manually adjust PID settings on your side every time.

3. Multi-point auto-tune feature is nice, but it is not universal to all the customers. Different customers have different set temperatures. If we preset several auto-tune temperatures like 300, 600, 900, etc, it may not cover the most important temperature from some customers. Also this feature will increase the total auto-tune time, and more parameters & settings are needed to be added to this controller. Considering the complexity of this ramp & soak controller, this feature may not be useful to all the customers.

Let me know how do you think.

[jbruce]

1. Yep, I understand how auto tune works.  I understand that it is best at a single temperature.  I have auto tuned at temperature that works well enough.

2. Now you're getting the idea.

3. I understand that the Awesome Auto Tune feature would not be used by all customers, but it would make it one of the best controllers for kilns on the market today.  The example temperatures of 300,600,900 etc were just examples.  You could probably do every 500 degrees and it would work great.

Anyway, just ideas for potential improvement.  Thanks for taking the time to reply.