Hello,

I'm struggling to get a program working to control a ceramic oven temperature.

- LOGO! 12/24v rce with analog and digital inputs
- Thermocouple sensor which outputs 0-10v (0-1200 C)
- Start button
- Stop button
- Selector switch 0 - 1 - 2

Now i would like the logo to operate a relay based on current temperature.

The oven has to heat up slowly in set steps in different fases.

fase 1:

temp rising 60 C per hour
start fase 2 when temp 200 C is reached.

fase 2:

temp rising 100 C per hour
start fase 3 when temp 600 C is reached

fase 3:

temp rising 150 C per hour
turn off oven when temp 1000 C is reached.

it is very important that the temperature rises slowly, this should be achieved by turning the relay on and off.

i hope this is enough info, if anything else is needed please let me know.

Thanks in advance.

The logo is 12/24rce, i dont know of Maybe that is different than 24rce

U_51046b6f-37e0-4329-b416-93861ba11506

I'm struggling to get a program working to control a ceramic oven temperature.

So you have made a program already? That is good. May we see it please. 

U_51046b6f-37e0-4329-b416-93861ba11506

Well, what is have now is that when i press the start button it starts the pi controller but i dont know how to go further from Here, i know i have to do something with timers but cant figure out how to let it switch the relais on and off every now and then to regulate a slow increase of temperature.

My opinion: It is unfair to wanting volunteers to design a program for you for free. (Yes we are users like you, helping for free.) Please do some effort and make something that can be used as a base for discussion. It will be an advantage to you in the long run.

Or contract some professional to do the work for you.

ixo65

 

U_51046b6f-37e0-4329-b416-93861ba11506

Well, what is have now is that when i press the start button it starts the pi controller but i dont know how to go further from Here, i know i have to do something with timers but cant figure out how to let it switch the relais on and off every now and then to regulate a slow increase of temperature.

In my opinion a PI controller isn't the right thing for your problem. 

 Can help me in the right direction? What is the right thing to use

Hello Auto-Gen,

The crucial question is how long does the heating element have to be switched on to heat the oven by 1°C ?

Only then can you estimate whether your time specifications per hour are actually correct. Then you could cycle the oven so that the heating element is switched on for a maximum time per cycle.

But remember that with your chosen thermocouple sensor, the Logo cannot display the exact degree. You always have a tolerance of +/- 1 to 2°C.

Greetings Ella_68

ixo65

May be this is what you want ...

 thanks for this Ixo65, it seems to work pretty well after testing. Only sometimes it doesnt go through to phase 2 even tho temperatures have reached the setp. 

Also like i mentioned in my starting post, i would like the possibility to have different times/temperatures with a 2 way switch, so state 1 does max 1000 degrees and state 2 does i.e. max 1200 degrees. how can i accomplish this without ruining the program?

Thanks in advance

ixo65

 

AutoGen_4030457

thanks for this Ixo65, it seems to work pretty well after testing. Only sometimes it doesnt go through to phase 2 even tho temperatures have reached the setp.

I have tested the program several times and just now again.
In my opinion, the error you describe (which sometimes occurs) is not possible.

AutoGen_4030457

Also like i mentioned in my starting post, i would like the possibility to have different times/temperatures with a 2 way switch, so state 1 does max 1000 degrees and state 2 does i.e. max 1200 degrees. how can i accomplish this without ruining the program?

I'm assuming that you don't have enough knowledge of LOGO! programming to implement the tips I gave you (if I gave them to you).
I've already given you a finished program. This would have to be completely adapted for phase 3.

Or come also there other values ​​for phases 1 and 2?

 Thank you for your quick response, maybe the error occured because of hardware failure, i will have to check that.

It is correct that my knowledge of LOGO! programming is limited, im learning a lot by working with the program you provided, thanks for that.

the values will change for all phases, actually there will be only 2 phases in the second state, below are the values :

ixo65

Then the program has to be changed completely.

And there are too many things in your description that are not clear and therefore cannot be easily programmed.

Example 1, you wrote:
Phase 1:
Temperature increase: 150 °C per hour.
End temp: 600 °C.
Time: 4 Hours

The time of 4 hours cannot be adhered to because I start the program with the current oven temperature. It will adjust itself depending on the oven temperature at the start. It does not start at 0 °C.

Example 2, you wrote:
Phase 2:
Temperature increase: 200 °C per hour.
End temp: 1060°C.
Time: 2+- hours
Total duration about 7hours.

I can't program that. Both "2+- hours" and the "total time of 7 hours". That contradicts everything.

 The times it takes to reach the end Temperature of that phase are just indications. The temp per hour and the end temp of that phase is what is important.

ixo65

Unrealistic guidelines are not helpful, they only confuse.

 Im sorry, i didnt know.

Fase 1:
Temprise: 150 °C per hour.
Endtemp: 600 °C.


Fase 2:

Temprise: 200 °C per hour.
Endtemp: 1060°C

AutoGen_4030457

ixo65

Unrealistic guidelines are not helpful, they only confuse.

 Im sorry, i didnt know.

Fase 1:
Temprise: 150 °C per hour.
Endtemp: 600 °C.


Fase 2:

Temprise: 200 °C per hour.
Endtemp: 1060°C

 I was thinking today that if it makes it easier for the program, it is also possible to split phase 1 into 2 phases.

so:

phase 1:
Temprise 150 C per hour
Endtemp: 300 C

phase2:
Temprise 150 C per hour
Endtemp 600 C

Phase 3:
Temprise 200C per hour
Endtemp 1060 C

i think if its made like this then there is still 3 phases so maybe easier to make? correct me if im wrong