Answer to hardware requiremnts for controlling RH of air

[manish]

I have an MKS mass flow controller capable of sending flow rate between 0-20 lpm.I have National Instruments labview and use National Instruments field point explorer to control voltage input to the mass flow controller. I also have omega RH sensors capable of sending RH readings in volts, which I read using the .iak files of the field point explorer. Now with all this could you please tell me whats the easiest way to program my application and make the RH sensor and mass flow controller to talk to each other using labview? If you have some code which does this please let me know.

[Bill B]

Hello,

Thank you for contacting National Instruments.

I will need some additional information in order to make a good recommendation on how to program this application. From your post, it appears that you would like to read the voltage from the RH sensor and send a voltage to the MKS using your FieldPoint hardware. Please let me know if this is incorrect. Here are my questions:

1. What FieldPoint Modules do you have? (ie. FP-AI-110)
2. What version of LabVIEW do you have?
3. What range of voltage does your RH sensor produce?
4. What range of voltage can your MKS receive?

I look forward to hearing from you. Simply reply to this posting.

Regards,
Bill B
Applications Engineer
National Instruments

[manish]

Hi
Thanks for your reply. I am new to using labview and hence having difficulties with programming my application. I also wanted to ask you that I would need to put in an equation which calculates the RH of the mixture of dry air steam and stream of known RH for this application. what would be the best way? I am not familiar with incorporating matlab scripts into labview.

Here are the information you asked for:

Field point modules:
FP-AI-110
FP-TC-120
FP-AO-210

Labview version 6i

The omega RH_4 gives a current output ranging 0.0035-0.021 Amps

The MKS takes input volatage ranging 1-5 Volts and gives corresponding flows between 0-20 lpm.

Please let me know if there are more questions.

I look forward to your reply.

You could email me
at manish_401202@yahoo.co.in

thanks
manish

[Bill B]

Hello,

More than likely you will need to put an equation in your application. Here is a simple example of how the application would flow:

1. Take a current measurement from the Omega using the FP-AI-110.
2. Use an equation to convert the current to units that are meaningful.
3. Use another equation to determine what voltage needs to be sent out to the MKS.
4. Use the FP-AO-210 to produce a voltage.
5. The MKS receives the voltage and does some action.

You do not need to use Matlab scripts. More than likely, you can do all of your equation coding in LabVIEW by using the Math pallette or you can use a formula node and program your formula like C code.

You may want to take a looks at some example programs that ship with LabVIEW fo
r assistance. Go to Help >> Find Examples and take a look.