10-04-2007 11:11 AM
10-04-2007 03:58 PM
10-05-2007 01:49 AM
Hi,
I agree with GWD probably you ar trying a continous acquisition or something like that and you are experiencing problems with the data transfer from the card to memory or to your program.
Post the code or provide the error code. But if the specifications show that this is the transfer rate it had been tested by NI.
10-05-2007 06:05 AM
10-05-2007 07:42 AM
10-05-2007 07:46 AM
Yes, I can understand that
The question is... it's supposed to be possible to acquire data from the four channels at full speed according to http://zone.ni.com/devzone/cda/tut/p/id/3039#toc3
What do I have to do to get this performance?
10-05-2007 11:16 AM
10-08-2007 01:55 AM
Hi,
As u can see the problem you are expericiencing means that data transfer is not fast enough for the board rate. That is... the board has an small internal memory (buffer) where the data measurements are stored. These information is loaded into the PC memory by means of DMA transfer normally. This data transfer from the device to the PC RAM memory is not fast enough, then the on-board buffer becomes full and data is overwritten producing the error.
But you are wrong when you say the board does not work. The board works, the problem is the rest of the system, coz the data cannot be passed to memory as fast as needed.
You can see tests had been done under a PXI-8351 controller:
http://sine.ni.com/nips/cds/view/p/lang/es/nid/202784
Also you need to set the Read Wait Time as Poll. Then, free O.S. as mentioned in previous posts, etc... Probably your system does not accomplish the same characteristics (or higher) than the 8351.
Hope this helps,
10-16-2007 05:30 AM
Hi again
Changing the board from slot 10 to slot 3 was enough to make it possible to acquire the 4 channels at full speed.
It seems that locating a board in a high numbered slot such as 10 means the data acquired has to pass through several PCI bridges until it gets to the controller, slowing bus operations and leading to a higher risk of overflow. Therefore I understand that boards with high data transfer requitements must be placed in lower numbered slots (particulary between 3 and 6 for a PXI-1044
Kind regards
Guillermo