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List:       comedi
Subject:    AI_FIFO_DEPTH for NI 6034E
From:       Vishnu Ranganathan <Vishnu () angleinc ! com>
Date:       2000-10-26 13:49:57
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Dave,

I'm not clear about what changes need to be made to read more than 255
samples from the AI FIFO.

You wrote:
> The AI FIFO depth is probably incorrectly configured.  It
> looks like the ai_fifo_depth parameter you are using is 1024, whereas
the
> correct FIFO depth is 512.

The file ni_pcimio.c has the following:
..
 {       device_id:      0x2ca0,
  name:           "pci-6034e",
  ..
  ai_fifo_depth:  512,
  ..
  },

When I read 255 samples (by setting cmd.stop_arg = 255) the read() call
in do_cmd() returns 510 as the number of bytes which is correct.
However, when I set cmd_stop.arg = 257, the read() call in cmd.c returns
1026. I would expect it to return 514.

What changes need to be made to read more than 255 samples from the AI
FIFO?

Vishnu




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