Hi,
Is there anyone who already made a code for PID, using MAX31855, K type thermocouple sensor, and SSR? I need to control the temperature in my kiln. For example, I need to get the temperature up to 300 degrees celsius and then hold it for an hour and then heat it up to 700 and hold it for 2 hours and after leave it to drop to 600 and keep it there for 30 min. I've searched hours on web for similar projects, but I had no luck. Just found a picture showing simple wiring without any code. Thanks in advance.
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Exactly the same project is never found. Learn about PWM and PID, what they can do and what they can't do. Then start developing the build.
Splitting the project into smaller pieces and searching for similar pieces is a better way solve the issue.
I understand. I will wait, maybe there is someone who once had similar project and can help me out.
While you are waiting, you could learn to use the thermocouple by following any of the many getting started tutorials, and learning about PID temperature control from any of the many tutorials posted for kilns, barbecues, wood stoves, etc.
Thank you 
Thank you for kindly advice. I did learn a lot midtime and found out how to control it. Now I only need some more knowledge how to make several loops in code for each temperature. I'm new in programing and I though that this site would be the best way to get some help. I was obviously wrong, because most of the advice is to learn. I already know that.
It be worth looking at PCB reflow oven projects - there are lots and same thing but different temperature range .
Meanwhile you’ll need some knowledge of working safely with higher voltages .
Bear in mind you can buy temperature controllers at reasonable prices .
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Thank you for your advice and concern. I will check. Yes, I do have the basics on high voltage. 
What you are describing is multi profile ramp and soak in temperature control. There are controllers specifically designed for this purpose. Years ago Omega Engineering marketed several controllers which did that, I recall the CN2011 model for some reason. I can tell you right now doing this with an Arduino will take some programming. If driving the kiln heating element with a SSR make sure the SSR is rated for the element temperature and if anything is going in the kiln of importance you may want to think about another thermocouple serving as an over temperature shut down.
What is a ramp soak controller?
Ramp / Soak Controllers. This type of controllers changes the setpoint according to the preset program pattern**. The program consists of raising/reducing the setpoint (ramp control) and keeping the setpoint at the preset level for a preset period (soak control).
A Google of "Arduino Ramp and Soak Control" should get you going in the right direction.
Ron
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You need only one loop. Your program should include an array of desired temperatures and times, and use millis() as the timekeeper. The loop will change the setpoint at the appropriate time.
Here is an example project for a "reflow oven", which is basically a tiny kiln for PCBs.
The author seems not to have learned about arrays, but it will give you an idea of how to proceed. You can probably find better examples.
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Thanks. Just so simple as I wish mine should be.
Nice. I am finally on the right track with all your suggestions. Thanks.
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