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dma interrupt transfer modes in 6602
Gérard
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12-13-2005 04:40 AM
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I am using four simultaneous counters of a 6602 in continuous buffer modes
using traditional DAQ. Gates used are PFI38 PFI 26 PFI 18 PFI 10.
When I use set DAQ Device Information.vi to specify the "data transfer
mode for GPCTR # " either in DMA (3 of them) or interruption mode ( one of
them), I am not sure which # to use for the GPCTR #.
In other words, must I specify GPCTR0, 3, 5 in DMA and GPCTR7 in interrupt?
Otherwise stated, the simple fact that I use predefined PFI would associate
the GPCTR concerned or, else, are these GPCTR defined as GPCTR0, 1, 2, and 3
in the order I open their configurations in my Labview program.
There is no clear definition of what GPCTR # actually mean in the Labview
references.
I have the feeling that some counters generating 15000 counts/sec do not use
DMA but interrupt transfer modes instead.
Gérard
using traditional DAQ. Gates used are PFI38 PFI 26 PFI 18 PFI 10.
When I use set DAQ Device Information.vi to specify the "data transfer
mode for GPCTR # " either in DMA (3 of them) or interruption mode ( one of
them), I am not sure which # to use for the GPCTR #.
In other words, must I specify GPCTR0, 3, 5 in DMA and GPCTR7 in interrupt?
Otherwise stated, the simple fact that I use predefined PFI would associate
the GPCTR concerned or, else, are these GPCTR defined as GPCTR0, 1, 2, and 3
in the order I open their configurations in my Labview program.
There is no clear definition of what GPCTR # actually mean in the Labview
references.
I have the feeling that some counters generating 15000 counts/sec do not use
DMA but interrupt transfer modes instead.
Gérard
falkpl
Trusted Enthusiast
12-13-2005 07:24 AM
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GPCTR# is the general purpose counter resource you are using, there are eight 32-bit counters on the 6602 card. Unfortunately there are only 3DMA channels which means that if you plan on 4 very high speed buffered counting acquisitions then you could have some trouble since interrupts run much slower than the DMA channels. I have had no problem using a mix of interrupts and DMA channels for continuously buffered counting with 4-8 counters at a time but the collection rate was only a few KHz faster than this the buffering using interrupts can not keep up an will overrun causing a "buffer overrun" error. If you really need many highspeed buffer counters running simultaneously you could try using 2 cards but this seems costly (RTSI cable will allow multi-card synchronization).
Paul
