Why is compact FP Strain measurement rate much slower than SCXI and DAQ module

[balaton]

Measuring Strain, Temperature Quadrature Encoding using Compact Field Point modules is much slower that using corresponding SCXI modules and a DAQ card even though each cFP module has its own AD converter. Why is this so?

[Wayne.C]

Are you talking about the update rates of the modules or the time to read a channel from your program?

Think of the update rate as how fast the A/D converter updates the channel information that is available to be read by a program.  Most cFP modules have update rates that are significantly slower than the PXI and DAQs.  I'm guessing that this is because NI decided that most users wanted the industrial hardening of the hardware and not necessarily the high speed.  The filter options you choose when you configure your modules in MAX can further slow them down.  If you look at the documentation for each module it specifies the speed penalties for different filter settings.

If the problem is how fast your program can read cFP channels, you need make sure that something in your program isn't slowing you down. 

[balaton]

I am talking about compact Field Point module updates.

[Brian_K.]

Hi,

Centerbolt is correct.  Because the FieldPoint modules meet more industrial specifications their speed is a trade-off.  Also consider that the cFP are distributed devices that communicate information via TCP and serial protocols.  Most applications can be satisfied with cFP speed.  And if they don't you can always use a faster alternative of real-time targets with a DAQ card inside of it.