04-23-2007 02:15 PM
04-24-2007 04:28 PM
04-25-2007 08:20 AM
Hi Adam,
Thanks for responding. From what you wrote I should expect slower rate through the MXI-4, 110 MB/s vs 78 MB/s. Which is an aproximate difference of 25%. With my configuration the transfer rate difference is about 50%, 30MB/s vs 20 MB/s. The size of the block is only 4000 bytes. Which I am sure is the reason for the slower transfer rate to start with. But what could account for the big decrease when the MXI is used? Is the MXI even less effecient at smaller block size? Or is there something else.
I just wanted to make sure that the results I am seeing are what I should expect. And data transfers through the MXI-4 are slower and can be 50% slower than the same tranfer over the PXI bus.
One another point. The 130 usec transfer time is the typical value but occasionally the transfer time spikes to 250+usecs.
Dave
04-26-2007 04:32 PM
06-07-2007 01:01 PM
I am confused about my system and it's PXI bus speed. It seems to me that the bus is operating at only 33 MHz. The bus analyzer indicates that the bus is operating at a 33 MHz rate.
And the Keithley pxi extension can be set to run at 66 MHz but when it is the digitizer data is corrupted. Does this indicate that the Aqiris digizer can only operate at 33 MHz?
Should the bus be able to operate at 66 MHz? How is it determined what speed the bus operates at? Is it determined by the ability of the "slowest" card in the system?
It seems to me that even if the pxi extension increases the transfer time from the digitzer, if the bus could be set to operate at 66 MHz the transfer time would be reduced.
Configuration
PXI-1031
pxi-8196 controller
NI mxi-4 or Keithley KPXI-CON-PXIREM pxi extension
Vangaurd PXI bus analyzer
PXI - 1056
NI mxi-4 or Keithley KPXI-CON-PXIREM pxi extension
Aqiris DC440 digitizer
06-08-2007 03:54 PM - edited 06-08-2007 03:54 PM
Message Edited by John E on 06-08-2007 03:56 PM