Mass flow control by FP-AI-110 and FP-AO-200

[Bo]

I have several questions related to use FP-AI-110 and FP-AO-200 to control Mass flow controler. Mass flow controller has a 15-pin D connector. Both the input and output are 4-20 mA. Firstly I connected only one MFC to channel 0 of FP-AI-110 and FP-AO-200.
(1)Iin and COM of FP-AI-110 was connected to two current output pins of MFC.
(2)Iout and COM of FP-AO-200 was connected to two current setpoint pins of MFC.
(3)Vsus and COM terminals of FP-AO-200 of which V and C terminal connected to external power supply of 24 V was connected to 2 pins of MFC D connector that needs 15-28 Vdc power supply according to MFC specification.
Now the problem is the reading of FP-AI-110 is 0 although the N2 gas was passing through the MFC. Fur
thermore, there is one error of code 33180 with FP-AO-200(The amount of data provided does not match the number of data items required or the number of channels to be addressed:FP Write.VI). Even though I regulate the output of FP-AO-200(setpoint for MFC), the gas flow rate of MFC didn't change.
Does FP-AO-200 control only by current output? Thanks a lot.

[Ben]

Hi Bo,

THe AO-200 is current only, unless you add additional circuitry.

I would suggest you put an ammeter in series with the output of the AO-200. Then work to get your code to reliably set the value you want. It sounds like you are having more than one issue. Keep things simple, get the basics working, and than gradually increase the complexity of the system.

Are these Brooks MFC's?

Ben

[JamesJ]

Is this a Brooks MFC.  I have used the Voltage or Current FP output modules to control the MFCs.  But i used a PID controller (from Watlow) for very good and even flow control.  I used the FP to send the voltage signal to the pid control which would send the control signal to the MFC.  This will eliminate the flow jumping around.