Difference between simple DAQ card and FPGA based DAQ card(like PCI 7831R)

[9029930714]

Could any one tell me, where should I use simple DAQ card and where should I use FPGA based DAQ card ? If I can take data acquisition from simple DAQ card then why we go to the FPGA based DAQ cards(like PCI 7831R) ?

[aeastet]

Well the FPGA is going to be more expensive so here is what I know about it:

You need FPGA when you need exact timing down to very low levels.

You need FPGA when you need a very robust operating system.

You need FPGA when you need very high speed system

You need FPGA when you need a flexible data acquisition system.

You need FPGA when you can not afford to lose data if something goes wrong (of course this still depends on your program).

[D Robertson]

In addition to the list above,

1. You need FPGA when your timing and/or triggering requirements are beyond the capability of DAQmx. (i.e. changing sample rates, or sampling different channels at different rates)
2. You need FPGA when you need to run control loops at speeds not achievable elsewhere (i.e. 100kHz - 40 MHz)
3. You need FPGA to do counters. (I know there will be folks who object to this statement, but unless you're doing something boring such as a pulse train or an encoder, the flexibility of the FPGA makes using counters easy.  And they can be used in so many applications.)

Dave

[John_P1]

I agree with everything on this list, except I think you may be underestimating the available uses for DAQ counters.  For example, take a look at this screenshot from the X Series User Manual:

       

Implementing counters on an FPGA does allow for very customized applications and use cases, but many of these may be equally achievable with a standard DAQ card at a much lower cost.

Best Regards,