LabVIEW

cancel
Showing results for 
Search instead for 
Did you mean: 

Mass flow controller with Labview

Dear All,

 

First of all I have to say I am a chemist not an engineer. That’s why I need some help or advice.

 

I have few mass flow controllers without the device which control them. I am trying to control them with Labview. Please find attached some pictures for more information.

 

I use NI USB6009. None of the controllers work. Probably the problem is the code or..

 

I will appreciate any help or advice. Thank you in advance.

Message 1 of 76
(10,697 Views)

Hi Bozhidar,

 

Probably the problem is the code or..

Yes, probably. But how should we help you when you don't provide any code? Attach your VI, especially for those DAQ ExpressVIs as they hide any information from the interested viewer…

 

Did you check the wiring? Twice?

Are you getting useful data from MF valve? Does the MF valve react on your AO signal?

You didn't specify the problem you have with your code and/or MF valves…

Best regards,
GerdW


using LV2016/2019/2021 on Win10/11+cRIO, TestStand2016/2019
Message 2 of 76
(10,549 Views)

Hi GerdW,

 

I checked the wiring several times. No problem there. The MFCs (3) do not respond to the signals from the USB6009. It could not be broken all.

Here the vi and pic of the wiring.  Sorry for the bad view but it is in my room not in the lab.

I use 0 to 5V range for the output.

Download All
0 Kudos
Message 3 of 76
(10,535 Views)

Hi Bozhidar,

 

The MFCs (3) do not respond to the signals from the USB6009. It could not be broken all.

So none of those MFCs do respond, but they aren't broken? Really sure?

 

What happens when you use a simple power supply to provide the control signal to the MFC? Does it react when you provide voltage in steps of 1V? Just to make sure the MFCs are ok (and your wiring is ok)?

 

On your VI:

- Your output range is set to [-100, +100]. That's a bit large when your MFC expects just 0…5V!

- What's the problem you aren't using AutoCleanup (Ctrl-U)? Your VI would gain a lot more readability…

- Why are ther two indicators named "Numeric"? To you use also same names for variables when you would use a textual programming language? (Btw. "Numeric" is a rather poor label for indicators!)

- Why do you use an additional numeric indicator for your Slide control? Why not right-click the control and select "Visible Items->numeric"?

- Using ExpressVIs leads you to use the dreaded DDT (DynamicDataType). That is not good to understand what's going on - and you get Coercion Dots as can be seen at the PID input…

- Why did you create a control for "dt (s)" when you just use the default value of the PID function? You don't need to wire default values! Instead of this I would use a wait function (e.g. 50ms) and wire that dt value to PID too!

- When using a more "conventional" loop timing you wouldn't need the PtByPtMedian function. Do you really need the Median - or do you want to average your input value?

Best regards,
GerdW


using LV2016/2019/2021 on Win10/11+cRIO, TestStand2016/2019
Message 4 of 76
(10,527 Views)

Hi GerdW,

 

Thank you for helping me. You have many questions and you will understand everything when you read the words "I am new for Labview".
I am a chemist and I work in our Academy of Sciences. I am building catalytic apparatus for testing of catalysts active on neutralisation of exhaust gases. Gas mixture - catalytic reactor with temperature control - analysis (gas chromatograph). The MFC are crucial for me. Its a long story but we have developed very active catalyst for automotive and now I have to build very cheap apparatus for routine tests (roughly sifted).

 

So none of those MFCs do respond, but they aren't broken? Really sure?

 Not sure but it could not be broken all. "I bought them as good condition".

 

What happens when you use a simple power supply to provide the control signal to the MFC? Does it react when you provide voltage in steps of 1V? Just to make sure the MFCs are ok (and your wiring is ok)?

I hear some clicking inside. For example purge option.

 

On your VI:

- Your output range is set to [-100, +100]. That's a bit large when your MFC expects just 0…5V!

Every time I change it 0 to 5. I do not know why in the file evrytime is 100...

 

- What's the problem you aren't using AutoCleanup (Ctrl-U)? Your VI would gain a lot more readability…

I write this VI just to check the MFC. The real program will be much more clear and precise: temperature control, schedule and etc.

 

- Why are ther two indicators named "Numeric"? To you use also same names for variables when you would use a textual programming language? (Btw. "Numeric" is a rather poor label for indicators!)

See previous

 

- Why do you use an additional numeric indicator for your Slide control? Why not right-click the control and select "Visible Items->numeric"?

I am not expierenced.

 

- Using ExpressVIs leads you to use the dreaded DDT (DynamicDataType). That is not good to understand what's going on - and you get Coercion Dots as can be seen at the PID input…

See previous

 

- Why did you create a control for "dt (s)" when you just use the default value of the PID function? You don't need to wire default values! Instead of this I would use a wait function (e.g. 50ms) and wire that dt value to PID too!

See previous

 

- When using a more "conventional" loop timing you wouldn't need the PtByPtMedian function. Do you really need the Median - or do you want to average your input value?

I am not sure I understand the last two question.

 

I have to eliminate the probable reasons that cause the problem. I wrote the VI after watching youtube. That's why I thought there was the problem.
Please advise.

 

Best regards,

Bozhidar

0 Kudos
Message 5 of 76
(10,505 Views)

A typical mass flow controlled simply accepts a voltage (0..5V) and sets the flow proportional to that voltage, independent of gas or fluid pressure. You seems to think that you need to do the PID regulation yourself, but all that is typically embedded in the controller.

 

Here is a link to the datasheet?

 

Can you explain exactly how you wired everything?

 

I assume htat your +/-15V is from a real power supply and not from a DAQ.

0 Kudos
Message 6 of 76
(10,494 Views)

Attached the wiring. I use external power supply for +/-15V.
Suggestions.

0 Kudos
Message 7 of 76
(10,474 Views)

As much as I see these devices are not controllable via serial (RS232 or RS485), so it does not have a built-in PID controller. If this is true, it is bad news, since it will require much more suffering during the development, specially if you are beginner in LabVIEW...

 

The only advice I can give you, if you have the budget, you should buy modern mass flow controllers which you can just easily operate via RS232 for example, and you can forget this stone-age analogue approach... There are lots of companies manifacturing MFCs, like Brooks, Bronkhorts, Pfeiffer, MKS, etc... Also, these come with ready made LabVIEW drivers. (Prices start around 1000 EUR, or cheaper if you buy second-hand ones).

 

edit: it was not easy to google out the manual, but here it is, just in case if you do not have it yet:

http://img19.ybzhan.cn/5/20110825/634498820774538750.pdf

 

edit2: I have found this info in the manual, at page 44, it is not totally clear however:

 

 POWER
COMMON
Common line that carries
the majority of the MFC
operating current.
Note:  POWER COMMON
 (pin 4) and
SIGNAL
COMMON
 (pins 7 and 😎 must be connected
at the power supply.

 

Sorry, this is for the 20-pin connector:

 

"OWER
COMMON
Common line that carries
the majority of the
MFC operating current.
Note:  POWER COMMON
 (pin 2) and
SIGNAL COMMON
 (pins B and C for
the card edge connector, pins 12 and 13
for the Honda connector) must be
connected at the power supply."

 

edit3: as I see, you did not connect anything to the power common. Actually the power connection wiring is somehow not clear to me from the pdf manual 🙂 Be careful, do not damage your NI HW 🙂

0 Kudos
Message 8 of 76
(10,451 Views)

Thank you Blokk! I have the manual.


Everybody knows how to do it with money. It is a challenge. I have to assemble the equipment from nuts and bolts in order to understand how it works and repair it easily after that. The rest of the equipment is also old or salvaged.
We have such equipment and it costs $k250. No budget for now.

 

So I receive the information for the gas flow from the MFC as voltage: 0 to 5V for the max flow and I order (voltage 0-5) to the MFC to open the valve. It sound simple.


I will appreciate any suggestion.

0 Kudos
Message 9 of 76
(10,437 Views)

edit3: as I see, you did not connect anything to the power common. Actually the power connection wiring is somehow not clear to me from the pdf manual Smiley Happy Be careful, do not damage your NI HW Smiley Happy

 

I connected -15V to power common and +15 to Valve test (D). Hear clicking of the valve on the MFC. It is purge option.

The MFC are normaly closed.

0 Kudos
Message 10 of 76
(10,424 Views)