Jingyan,
the 7831R is an multifunction I/O board with a reconfigurable FPGA onboard that can be programmed with
LabVIEW FPGA. You can expect PID performance of up to 100 kHz. The more complex your algorithm is the slower is the performance but as you don't run the control loop on a CPU but on an FPGA you can parallelize many calculations so you don't have to sum up the time needed for each calculation so a targeted loop rate of > 20 kHz is realistic.
For motion control applications NI has developed the NI SoftMotion module. This software module provides all components needed to create a software based motion controller (e. g. trajectory generator and spline calculations). For more information please click
here.
The FPGA has a limited amount of gates that can be used for your application and there is no floating point unit on it so you should run only the control algorithm on the FPGA. Everything else like trajectory generation, limit switch monitoring, calculation of the spline parameters and so on should run on the host system.
As the host system needs to be synchronized to the application running on the FPGA it can't run on a non deterministic operating system like Windows. This is why you need
LabVIEW RT and a
PXI based setup.
Based on the shipping examples I have successfully created an FPGA/RT based SoftMotion controller so please feel free to post detailed questions to this thread.
Best regards,
http://forums.ni.com/ni/board/post?board.id=240&message.reply_to_id=1930#
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Jochen
National Instruments Germany
