PCI 6221 speed

[JPrakash]

Dear friends,

                       I have used USB 6221 for my previous DAQ application. Now I want to change over to PCI 6221. Please advise if the change to PCI will be of any advantage to me, on the basis of operating speed and efficiency?  

[kikiduu]

PCI devices transfer data to system memory using DMA while USB uses interrupts to transfer data. This can probably create performance dip in USB when trying for high data rates compared to PCI. Also you cannot use SCXI Signal conditioning with USB which is possible with PCI.

But what exactly you want to do with the DAQ card? Are you not able to do it with present USB card?

[RT4CY]

Hello Jprakash,

The information in the previous post is absolutely correct.  The main advantage to USB is that it is very plug and play.  PCI and PCI Express will provide much higher throughput than USB (DMA transfer versus interrupts).  There are ways to synchronize multiple PCI devices through a RTSI connection.  However, your best bet is PXI if you are building a multi-device system.  For a good white paper which discusses the advantages to using a certain bus (USB, PCI, etc.), see the following article.