Please provide more information on the make/model of the Matheson MFC that you are using. Some specific questions that would enable people to better help you are:
How are you trying to talk to the MFC? Does the MFC have Analog Input channels that you will use a FieldPoint Analog Output module to control or does it have its own communication interface? Provide a link to the specs/user manual if it is available on the web.
What programming environment are you using?
Regards,
Aaron
LabVIEW Champion, CLA, CPI