Device Automation and Temperature Control

[akhil011235]

Hi...

I am new to LabVIEW. My masters project is on Automation and Sample control in Molecular Beam Epitaxy. As a starting step, I've to design LabVIEW programs for the shutter control[simply device automation... there are 8 shutters in the machine, with open and close commands] and temperature control.

I've LabVIEW 8.5 Developers Suite installed on my laptop. I've also purchased a NI USB-6008.

Could any of you please give me some advices about how to start with this project? I've worked out all of the examples given on the getting started window of LabVIEW.

Thanking you,

Akhil Rajan.

[MikeS81]

Hi Akhil Rajan,

welcome to the forum.

How can you send commands to your shutters? What do you want to make with the NI USB-6008?

Mike

Message Edited by MikeS81 on 05-19-2008 03:50 PM

[akhil011235]

Hi Mike,

Thank you so much for the quick reply.

Btw, right now we are controlling the shutters manually[Our's is a V 80 H MBE machine from Oxford Instruments]. What we need to do is automate the open/close function. I was told to design a program for the automation of shutters and then to design a program to control the temperature inside the chamber. Actually the USB-6008 will be using as an interface between the computer and the MBE machine.

Does this make any sense? If not please tell me. I'll try to explain in detail.

Thanking you once again for the help.........

Akhil. 

[Mathan]

Basically how you are implementing the open/close function? Do you have any dll for that function?

Mathan

[akhil011235]

Hi

Please bear with me. Actually I didnt think about such a fast and efficient support from this community. Thanks a lot.

I'll ask about the open/close implimenting functions from my supervisor and get back to you.

Once again million thanks for staying in touch with me.........

Akhil.

[akhil011235]

We dont have any dll for the open close functions.

In order to open and close the shutters, what we do is simply switch the voltage of the USB 6008 from +5 to -5.

Message Edited by akhil011235 on 05-21-2008 06:24 AM

[johnsold]

The USB-6008 only has 2 analog outputs which can switch between +5 V and -5 V. That would let you control two shutters but not all eight. Perhaps you could connect eight analog switches externally and control them with digital output lines (device has 12 digital lines).

Do you know anything about control system design or is this what you are supposed to be learning for your degree?

Lynn

[akhil011235]

Hi...

I dont have any previous experience with control system designs. I've just finished my MS in Nanotechnology. This problem is related to my summer project. Here the main objective is to automate the MBE machine. I need to design a LabVIEW program to control the shutter automatically [this is a starting step].

For eg: Open shutter 1 [for 5 sec]

             Open shutter 2 [for 5 sec]

             close shutter 3

             close shutter 4

             close shutter 5

             close shutter 6

             close shutter 7

             close shutter 8.

this is a typical example. here two of the shutters remain open for the time, and all others remain closed. after the given time, another two shutters get open and al others remain closed. this process continues according to our commands.

Even though I dont have any experience in control systems, I wish to do this because it will be a help for my PhD studies.

[johnsold]

OK. I would break this project down into several pieces.

First, define the hardware requirements: What voltage and current is required to open and close each shutter. What kind of signal is needed to control the temperature? How is the temperature sensed? Do you sense the shutter position or just assume it goes where the voltage commands it to go?

Next, define the functional requirements: What is the system to do and when? This includes the shutter timing, the temperature setpoint or profile, user interface, data display and analysis.

Once you have the requirements defined, then you can determine the resources needed to implement this. As I mentioned in an earlier post, the USB 6008 may not be suitable for your needs.

Then you select an architecture for your program. A state machine producer/consumer model might be a good starting point.

While working on the first two or three items you may also want to go through the LabVIEW tutorials. You cannot do a good job of designing and implementing a system without being familiar with the tools which will be used.

Lynn

[akhil011235]

Let me answer you questions.....

First of all please avoid temperature. Sorry for adding temperature in this topic. Temperature has nothing to do with the shutter control.

we can see the shutter opening and closing. it is visible.

Now we are controlling the shutters using a manual shutter control[ it is a box with several turning knobs and keys] which is directly connected to the MBE machine. to be precise, currently, our system contains no computers; but the MBE machine and the shutter box!

What we want to do is use the USB 6008 [if its not suitable we'll use another one] as an interface between the shutter control box and the computer. So by designing a LabVIEW program we can control the shutters automatically.

some background info: the molecular beam epitaxy machine is used to grow nano structured devices like semiconductors. we can place eight different materials on eight effusion cells. these cells are fitted with shutters. by opening two shutters at a time, two different materials from two effusion cells will enter the growth chamber and undergoes the growth process. We need to control the shutter timings as well. simply we need to open the desired shutters only for a certain time.

the growth process can be traced by a technique called RHEED. images can be obtained from this.

Please let me know if I've missed something. Thank you so much for you help.........