help with temperature control

[nw]

 I need your help. guys

     I built a close loop project on water temperature control. my objective is to control the temperature of water in a heating pot. the material i have are

heating pot ( deep fryer) 115vac

 cooling fan 115 vac

water pump 12 vdc

heat sensor

relays

pwm

my objective is to create a code to control the project.  are there codes to control these hard ware. I wanted to design codes that will turn on or off heating pot when the heating sensor detected a temperature setpoint about 90 degree F or high limit.   After rearched 90 deg F the code will turn of the heating pot do you know to put a time delay of 5 seconds after the water pot turned off.

                       After 5 seconds the water pump started to pump.  is there a code for the  P W M or pulse width modulation where it will control the speed of the water pump. from slow to fast.  ater the water pump started another 5 seconds of delay for the cooling fan to turn on. the fan will cool down  water through a cooling radiator.    when the water temperature rearched a cooling temperature of 80 deg F or low limit then the heating pot started to turn on again.

sir, do you or anyone in here know something like i described

[Doug M]

This is simple to do using the PID VIs of the PID toolkit.  Depending on what hardware you have you will need to include the correct driver calls to translate the output of the PID VIs to the appropriate input to your hardware driver.

[nw]

thank you, sir

that is very helpful. however, i only have labview 7.1 student editon. I dont have a lot of code in it, is there a site that i can download the codes.

thank again

[Doug M]

There is a fair amount of information on our website about PID theory.  If you don't have access to the toolkit you can write your own implementation.  There are some examples on our website, but they aren't all well-written.  Here is one.

[nw]

sorry to bug you again,

i opened one of the files, but some codes are missing, and it had a broken arrow, from the simple pid demo,

[nw]

I have a little attachment, can you tell me if i'm heading in the right track

thank you

[Doug M]

nw,

I can't really tell what the VI is doing that you attached, but here is what I would suggest -- you could either implement a PID type algorithm similar to the example I pointed you to, or it sounds like in your case you only need to do things at a fairly slow rate and you also want some delays, so you may want to implement a simple state machine architecture.  There are LabVIEW shipping examples that demonstrate the state machine architecture.

[nw]

hi agian DM

For my project, do i need to set up an i/o channel code to interface the soft ware with the hardware

thank you again,

[Doug M]

nw,

What you put in your code for your hardware depends on what hardware you are using -- if you are using a National Instruments DAQ device you will probably want to do single point I/O with NI-DAQmx, if you are using a National Instruments FieldPoint device you would use the FieldPoint I/O Point, if you are using a third party device you would use the device driver for the device...

[nw]

hello chief,

Im putting codes for DaQ, how i still needed help on codes about a  " AI multi port " or ' OI multi port ", where can i find these codes so that i can add io channel?

once again thanks