Mass flow controller with Labview

[Blokk]

DAQ is just a general term, what do you exactly mean about it? By the way, here is a pci devicenet card: http://sine.ni.com/nips/cds/view/p/lang/en/nid/207761

[Blokk]

I am also worried a bit about the project safety. Can you get some help with setting up the piping there? Thanks God you only play with nitrogen, and not hydrogen. Still, if you have a standard gas bottle, you can have pressures in it around 100 bar or more. Do NOT connect your MFC directly to the gas bottle! Always use proper pressure reducer on your high pressure bottle.

Back to the MFC control: i think, if this is a device net type, you can only use devicenet interface. You could try to sell the mfc, and buy one which you can control with analogue voltage signal, or via RS232...

[mechatroniclover]

hello
an ordiniary DAQ for example NI USB 6008 DAQ.
here is a schematic similar to my expected  work.

[mechatroniclover]

I will use pressure regulator after N2 cylinder and befor MFC. like the picture here.

in my e nose system I will need to read some gas sensors and control some electronic (solenoid) valves. I will do this using a DAQ( for example NI USB 6008 DAQ) and LabView. The sole problem here is to add a MFC to this system and to maintain Flow rate on 1000 sccm during the tests.
I need a MFC that I can controll it using my DAQ and also be able to monitor it on the same labview user  interface that will be for the whole e nose system.
what should I do exactly? 😞

[Dennis_Knutson]

Why did you buy that mfc if you wanted to control it with a DAQ device? That seems to have been a waste of time and money. You now need to buy a different one. That's pretty simple to understand. This time, pay attention to the interface type.

[Blokk]

Try to buy a mfc which is controllable by analogue signals. An example:

http://www.brooksinstrument.com/component/jdownloads/send/26-instruction-manuals/29-sla7800-compact-...

See page 1-2 for a Analog I/O port pinout, a D-sub port with 9 pins:

use pins 3-4 to supply DC voltage between +13.5 and +27 Volts so you power the mfc,

use pins 6-8 to vary the mfc setpoint with a DC voltage signal (analog output on USB-6008, 0-5V),

use pins 2-7 to read the actual flow, between 0-5 V voltage signal full scale (5V = maximum specified flow).

[mechatroniclover]

Thanks for the answers
Buying that MFC was a mistake and waste of time and money.Also that was the cheapest one (100 $).

I wish I could control that MFC but it seems expensive and time consuming. So I should buy another MFC. But if there is any other way to control this MFC using LabView and a NI USB 6008 DAQ please tell me. Here is my MFC:
If there is no way, so which type of MFC should I buy? 
9 pin or 15 pin?

[Blokk]

I beleive, there is no way to control a DEvicenet interface using a DAQ USB-6008.

"If there is no way, so which type of MFC should I buy? 
9 pin or 15 pin?"

Both should be ok (you will just need a different D-sub socket to make or buy), but be sure and double check the manual before you buy. You need a MFC which can be controlled using 0-5 V voltage signal, and creates an analogue output proportional to the actual flow rate (between 0 and 5 V DC).

The best if you post here the model which you find, so we can have a look.

Do not forget, you will also need a proper power supply with DC voltage inside the required range specified in the MFC's manual. Also be very careful when you do the wiring, you can damage your MFC if something wired incorrectly.

EDIT: another option which you can consider is buying a MFC with RS232 interface. Many MFC has RS232 pins beside the analogue control/read option. Either you have RS232 (also called "serial port" often) already in your PC, or you can buy cheap USB-RS232 converters (few EURs, try to get models with FTDI chip, usually they work good with LabVIEW). If you get an MFC with RS232 interface, you even do not need the USB-6008 to use. You simply use RS232 communication between the PC and the MFC. Many MFC models have LabVIEW drivers available for RS232, but even if not, using the manual, you can figure out the serial commands which you need to program in LabVIEW...

But still, you will need a power supply (PSU).

[Bozhidar4o]

I bought few MFC for 20-40USD Tylan. I control them with 5VDC and use USB 6009 just to monitor them. Read all posts carefully. Try to find on ebay cheap MFC with card edge 20pin. The normal price is less than $50.

[mechatroniclover]

thanks for the answers specially for Blokk's explanations.
my goal is to maintain 1000 sccm flow rate. What is the mentioned sccm on the MFCs? Is it the final range?
So should I buy a 2000 sccm MFC and control it for example using a 2.5 volt, or a 1000 sccm MFC control it using 5 volt?

What will be the correct connections and piping? should I use 2 valves beside the MFC like this?
an other important question: To what pressure should the N2 gas be reduced using a pressure regulator befor the MFC?