temperature profile PID control

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dzhang
Beiträge: 1
Registriert: Mittwoch 15. Juli 2009, 09:36

temperature profile PID control

Beitrag von dzhang » Mittwoch 15. Juli 2009, 09:48

Hallo forum,

I am new to Profilab and need some help. I wish to make a temperature profile program which allows the user to input a profile:
eg, hold for 10 mins, then heat up to 250 deg, hold for 20 mins, cool down to 100 degs etc etc). The number of steps has to be totally
user-definable and could vary from 2 or 3 to over 50.

When the user inputs this profile it will then be PID controlled within the program and hence communicate to a powersupply to output the profile.

Would anyone have any idea how I could do this? The progrram will need to execute each step in turn, calculating the setpoint all the time.

If there are any suggestions on how I would be able to make this profiler and hence use the PID tools in Profilab to control it please advice me.
I do not speak German so if you could please reply using english :D
Danke schon!!

KAKTUS
Beiträge: 645
Registriert: Samstag 18. Oktober 2008, 21:12

Re: temperature profile PID control

Beitrag von KAKTUS » Mittwoch 15. Juli 2009, 22:13

Hi,

please take a look to example nr.3 y(t) schreiber.

With this example you can first record a profile in realtime and later you can play your recorded profile.
Maybe this are the first parts for your projekt.
stachlige Grüße, Kaktus

Microprocessor
Beiträge: 79
Registriert: Montag 27. Oktober 2008, 00:03

Re: temperature profile PID control

Beitrag von Microprocessor » Donnerstag 16. Juli 2009, 01:58

Hi dzhang,

welcome to the club!

Appended a sketch I hope you'll find useful.

I do not understand if you are planning a time-controlled or temperature-controlled project so I focused on
editing an userdefined profile and running (playing) it to control whatever you want. So I left a little bit of
work for you,

Using RAM to enter all necessary informations seems to be an appropriate method because the entered
content may be saved into files, so the profiles are re-loadable and re-runable. Be sure to save both RAMs
(Duration-RAM and Mode-RAM) for a proper re-run !!
Another advantage is the opportunity to create test-data as plain text-files with other applications and load them
into the Rams if required.

Each event, consisting of duration (1st RAM) and mode (heating, cooling and hold) (2nd RAM), is entered into consecutive addresses.

To do this, first select the input-mode by setting the selection-switch to "Input" (off). Enter the first event-no.
which should be 00 normally, then the duration of the event and last the mode. In this example following
modes are defined:

Mode = 0 : hold
Mode = 1 : cool
Mode = 2 : heat

Only 4 bits are used in the Mode-Ram, so 16 different modes are available.

After each entry-set click the WRITE-button.
You may check your entries by entering an event-no. The contents will be shown in the RUN-section.

At this stage there is no break-condition at the end of the profile so be sure to enter a non-dangerous mode
for the last entry.

To run the profile select the RUN-mode by setting the selection-switch to "RUN" (high) then press the RST-button
first to reset the addresscounter and press the RUN-button afterwards. The duration from the ram-entry will be compared with the clock and in the case of equality the clock is resetted and the addresscounter will be incremented to the next event. In the time of "duration" the corresponding mode-entry will be active. All informations of the actual set will be diplayed in the Run-section.

Following test-data are stored to the rams:

Event Duration Mode
00 12 1 Cool
01 08 2 Heat
02 10 0 Hold
03 05 1 Cool

For test-purposes the resolution is calculated in seconds. Use the $Hours and $Minutes as source for the formula
instead of $Minutes and $Seconds.

I didn't invest much time in shaping the frontpanel. Hope you won't be confused.
If needed for your final project use other possibilties to enter data-sets for higher convenience instead of the HEX-Selectors.

If there are further questions please don't hesitate to contact me.

I wish you success developing you project.

With kind regards

microprocessor
Dateianhänge
profile.prj
(16.35 KiB) 416-mal heruntergeladen

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