I am seeking information on thermal cycle testing automation.

[DPIM]

I am seeking information on thermal cycle testing automation. I am using Labview 7 to perform an 8 cycle thermal test with a performance test at -25C and 65C with an end-of-line test at the end of the 8 cycles. I am looking for a way to automate. I have the equipment to control the PLC temp. controller. I just need to know if anyone has encountered this type of test. Thanks.

[tbob]

I have used Labview to create automated temperature cycling tests. The temperature chamber I used had a GPIB interface. I used Labview GPIB Write functions to set the temperature. Then I used GPIB Read to read the current temperature and stayed in a reading loop until the desired temperature was reached, then I performed my tests. I found that this was the easiest method to use. If you are using a PLC, you will have to search for a Labview driver for the PLC brand that you are using. Go to ni.com and type PLC in the search box. There you will find info on some of the most popular PLC's including Allen Bradley, GE Fanuc, Seimens, etc...

[Dennis_Knutson]

I've done a lot of this as well though I use TestStand to control the testing. Basically, I send a series of set points and dwell times. I command the chamber to go to a set point and monitor the temp. When the set point is reached, tests are done for the entire dwell time. When the dwell time is up, a new setpoint is sent and the process repeats. Since you're just using LabVIEW, all the code I use won't help that much but I have attached a VI I use that creates the temp profile. Just ignore the TestStand stuff in the OK event and use the setpoint and dwell time arrays if you want.

[microbes]

Hi Dennis,

I have gone through your LABVIEW code but finding bit hard to understand,Basically my application is something very similar to what your did,Actually I need to do thermal cycling for just three temperatures.So the labview program should control one temperature say for specified length of time and than it goes to to another temperature where it is controlled for desired time and so on.For example first it should be at 95degC for 1 min than it goes to 55degC for 1 min and than to 77deg C for 1 min and again comes back to 95 degc ...so on this continues for desired number of cycle.From your code what I see is that you have very similar application and it would be really helpful for me in developing such a temperature cycling for my application.I would really appreciate your help and would like to know the details of your code.

When I am opening your code it has some missing files for example "Create Test data cluster.vi" was not found ,also "setproperty value(numeric array).vi" is also not found ..so can you explain me what they stand for and how can use other part of your code in developing my application.I am also succesful in controlling one temperature using a USB-DAQ,sensor,heater and PID control of LABVIEW but unable to automate the process for thermal cycling where three temperature can be controlled for specified length of time automatically.

I will be really thankful for your help and suggestions and looking forward to hear from you soon,

take care

Bye

Ahsan

[Dennis_Knutson]

The missing code is the TestStand functions I mentioned. Just delete all of that and leave the code in the 'Chart' event. All that does is display a single profile that you create with a couple of arrays. The setpoint array and dwell time array along with the number of cycles is all that is required. Pass this information to a while loops with autoindexing turned on for the inner loop. The inner most while loop would terminate when the dwell time has elapsed. The next setpoint and dwell time would then be used. The outer while loop would terminate when the number of cycles has been performed. Here's a quick example of how it might look.

Message Edited by Dennis Knutson on 05-30-2007 07:51 PM

[microbes]

Hi Dennis,

Thanks a lot for your suggestion and example.Well I am finding bit hard to put all codes together.But I am sure that its doable with the technique you told.I am sending you my code for temperature controller which is basically PID based temperature controller and controls one temperature at a time.What I need is to put it in event structure which you used for your application and achieve three different setpoints which are controlled through this code of temperature controller for specified length of time.

I have also written code which you send it to me for different setpoints and dwell times.Finally what need to be done is to put these code together in order to achieve my goal.I am sending you all these codes,I hope they make sense to you.I will be highly thankful to you for providing me your help and suggestions in order to achive thermal cycling with labview.Thanks a lot for giving your valuable time on it.

Please find attached codes.

Take care

bye

Ahsan

[microbes]

Hi Dennis,

Please omit one of the temperature controller vi,Instead I am sending you pic file incase if you are unable to open it.Sorry for inconvenience.Thanks...

with regards,

Ahsan

[SamboNI]

Hi microbes,

I see in your code the general mechanism to do PID, and appears correct.

You mention integratring this dwell time structure and an event structure... could you be specific in what areas are not working for you and how we can help you out?

Best regards,

[microbes]

Hi SamboNI,

Thanks for going through my code.Presently my temperature control code has one set point but actually for my application i need to change this set point automatically after certain interval of time thats why I wanted to incorprate dwell time and even structure to do so.if there is any other way through which it can be achieved i would be grateful to know that.

I can provide you algorithm of what my application needs.basically I want to built a thermal cycling code, right now what I have is single point (setpoint) temperature controller.There fore in my present temperature control code i need to change setpoint automatically for example let my first set point be 95 deg ,once it has been reached it should stay there for certain interval of time (first dwell time provided by user) after that  the setpoint should change to 55deg and once it has been reached it should stay there for certain interval of time(second dwell time provided by user)after that the setpoint should change to 77deg and once it has been reached it should also stay for certain interval of time(third dwell time provided by user) so this makes one cycle in the second cycle again the setpoint comes back to first setpoint (that is 95 deg) and the whole thing is repeated and this should go on for certain number of cycles (provided by user).

Therefore I thought that using EVENT structure and dwell times it could be possible to do thermal cycling but I am unable to integrate all these three codes together.I will really appreciate your help in bulding my code.Please provide me a way to that and I hope that my algorith makes sense.Looking to hear from you soon,

take care

bye

Ahsan

[SamboNI]

Hi microbes,

I don't really think an event structure would be appropriate for this type of application, as you are not taking in and responding to user input. Since you are going to have a collection of temperatures, and you go through each one, here is my idea for an architecture:

1) Make a 1D array of numerics, for your temperature.
2) Pass this into a while loop.
3) Take out the first element, set your setpoint to this.
4) Iterate until your specified time has elapsed ("dwell time", possible another 1-D array)
5) Repeat with subsequent elements of the array.

Hope that gets you pointed in the right direction!

Best regards,