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Programmable control system software using LabVIEW

Hi everyone, I'm new to LabVIEW and haven't had any past experience using it. I have been given a task to create a program which is capable of inputting a set point temperature profile and communicating this profile to a PID controller. The PID controller will connect to a power supply and have it regulate current and voltage to a heater to obtain the set point temperature profile. A thermocouple will be used for feedback to the PID controller. Throughout the process there also needs to be a data logging function. In the lab we have an Agilent 34970A data logger.

 

I wish to ask what sort of information about hardware I need to start this project and how I can use labVIEW to firstly create a program for the set point profiles, and have it communicate and program into the PID controller this profile?

 

Note: Sorry if my explanations sounds noob, I've had very little software engineering experience.

 

 

 

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Many of your questions can be answered by reading the programming manual for your controller. Most use a regular serial port for hardware and don't need additional hardware. The software is generally either SCPI or a proprietary protocol. Some controllers use a GPIB interface which will require a GPIB controller in your PC. As for logging, you can retrieve some information from your PID controller. If you need to log from your Agilent hardware, you should be able to communicate with it via your serial port (a separate port from the one talking with your PID controller.) NI offers GPIB controllers for pretty much any PC configuration you might have.

 

As for LabVIEW software to control your application, your best bet is to dig into the examples available within LabVIEW and on this site. Instrument control and data acquisition are central to LabVIEW and there are hundreds of examples available. You must have the programming manual for your hardware, though. You won't get far without it.

Message Edited by lars on 05-18-2009 10:54 AM
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Thanks lars for your quick reply, sorry for my late one.

 

Would it be easier to communicate a profile to a PID controller or to use labVIEW to make a PID controller VI. Some parameters for the PID (KI, KP, KD) should be able to be defined by the user. What im trying to ask is if you can set these parameters using a VI to communicate to the PID controller or does it only work by making a PID control in labVIEW?

 

You mentioned the hardware connection to the computer. Would a PID controller connect to the computer via the RS232/485?

 

Thanks again for your time

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Although I've got quite a bit of experience with instrumentation control, I'm kinda limited on enviro chambers. If your recipe is on the simple side, I would tend towards letting the PID controller in the chamber control the chamber and use your LabVIEW to pass parameters, triggers, setpoints, etc. If your recipe is complex, you may benefit from writing it all in LabVIEW, you should probably keep asking questions to get other opinions, though. LabVIEW does have a PID toolkit that works pretty well, I've used it for a few applications.

 

Most of the chambers I've worked with have had a RS232/485 interface. If yours has one, that would be the easiest way to communicate. Chambers that don't have a serial port can generally be upgraded. A quick call to the manufacturer would let you know.

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Thanks lars for your reply.

 

The price for LabVIEW developer suite is quite expensive (i need the functionality the developer suite offers)...is there any other programs or software that can also create control systems and sort of be able to do what my application needs?

 

 labVIEw is like a final option but would prefer for a cheaper alternative.

 

Thanks

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Well, technically, you can probably write your program in any language that can reach the serial port. In reality though, LabVIEW is the only solution I would consider because of it's incredible support and wide array of prebuilt code. Developer Suite is an incredibly complete tool suite, you sure you need all that functionality? I believe that most people who buy Developer Suite do it to bundle other needed tools like FPGA, TestStand, Vision/Motion, etc which brings the price per tool down. Most of the techs here doing chamber work use the Full Development Package which works fine if you don't need to distribute your applications. To build excutables, one or two people here have a Professional Development package just for that reason and we build executables for our other 30 developers.
Message Edited by lars on 05-28-2009 07:27 AM
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hey lars

 

yeah I have thought that the full package would be sufficient bundled with a PID toolkit incase i wish to write a PID algorithm...but yeah, i had a budget to work with and the cost of labVIEW is higher. I agree labVIEW would be the best to use, but i have to still work within the budget and the basic version has not got enough functionality. 

 I had a look at Profilab 4.0 Expert...but i will look further for more programs..thanks for your input!

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Good luck in your search Smiley Wink

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