Max. frequency of acquiring data in PCI 6515

[Reshah]

Hello,

I'm using PCI 6515 digital inputs to acquire a 64K quadrature encoder pulses attached to a motor with maximum speed of 3000 RPM. The encoder has two options of resolutions/revolution (32K or 64K). At this rate, with 3000 rpm speed - or 0.02 revolution/sec - the encoder produce pulses at 2.73 MHz (if 32K resolution is selected) or 5.46 MHz (if 64K resolution is selected). I looked in the datasheet and user manual of PCI 6515 (http://www.ni.com/pdf/manuals/372172b.pdf) but I couldn't find whether PCI 6515 digital inputs can successfully acquire or detect the encoder pulses at this rate.

I really appreciate your help.

Thanks.

[Kevin_Price]

Very doubtful, by my reading of the specifications.  The section labeled data transfers does not include DMA, only the much slower interrupts and programmed I/O.  The manual referenced change detection but nothing about a timing engine.

Even if you could capture the digital signals, you'd still have to decode it into position information in software.  It's much more practical to use a device with a counter that has built-in support for quadrature encoders.  It'll be able to handle those signal speeds, and it will do the decoding in hardware, giving you incremental position measurements directly.

NI's X-series multifunction boards would be a good place to start looking.

-Kevin P