Re: NI-6111 and Comedi

Dear Juan,

welcome to the club of frustrated NI-611x board users.

On Mon, Jul 15, 2002 at 07:11:25PM -0400, Juan Gonzalez wrote:

> I've been trying to use the NI-6111 DAQ with the Comedi driver, but with
> only limited success.  My goal is simply to drive an analog output signal
> and to read an analog input signal.  There seems to be some problems,
> especially on the input side.  I've read some of the recent archives on this
> topic, but I'm not clear as to whether the code now works correctly for this
> device or not.

It does not.

> However, there are problems on the analog input side.  The command "./inp"
> does not seem to work.  I get errors like "ni_E: timeout 1" and "ni_E:
> timeout 2".  Has anyone else seen this?

Yes, sure, all the time.

> I looked into the driver code and started experimenting with it.  The
> timeout occurs in the function ni_ai_insn_read (in ni_mio_common.c).  It
> appears that after the strobe to AI_CONVERT_Pulse, the ADC FIFO remains
> empty, no matter how long we wait.

... or at least the AILWEF flag (bit 7) in the 611x Status register
(Offset 1) seems to indicate that the FIFO remains empty. I don't know
where the error is.

>  Increasing the timeout value doesn't seem to improve things.
>  However, if I strobe the AI_CONVERT_Pulse a second time, then I get
>  some data in the FIFO (!?).  

I assume you are doubling the command
"win_out(1,AI_Command_1_Register);"? - This works for me in
ni_ai_insn_read() (no "timeout 2" message, i.e., AILWEF has been set
here apparently) but not in ni_load_channelgain_list() (timeout 1)
called from ni_ai_insn_read() and ni_ai_cmd().

> I'm not sure exactly what is happening here since National
> Instruments has not published the register level description for the
> 6111.

Even with this description, it is not clear why this happens.

> Does Comedi handle analog input for this device?

No. It is broken, I am afraid. My guess is that there is a special
little magic that needs to be done with these boards, that is not done
by comedi.

Best wishes,
Rolf


-- 
Rolf Mueller, rolf.mueller_at_uni-tuebingen.de
Biosonar Lab, Tuebingen University,
Morgenstelle 28, 72076 Tuebingen
Phone +49 7071 29-74838  Fax. +49 7071 292618

Received on 2002-07-16Z06:13:54