PCI-6733 acting strange after a reboot

[gpettit]

Greetings,

I am using RTAI real time Linux and the COMEDI drivers to drive both a PCI-6602 and a PCI-6733 in a realtime control system.  I understand NI does not support the COMEDI drivers; however, I wanted to take a minute to describe the issue I am having to see if anyone had any insight.

I have written a small example that generates a 10Hz sine wave.  The example writes to the DAC0 channel in Immediate mode every 2ms.   Heres the problem I am having.  If I turn the machine off, unplug from the wall, plug it back in, and restart the machine and my program everthing works fine.  If I reboot the machine and then run my program the DAC acts very strange.   It appears as if the data is corrupt.  I also notice that  DAC1 also has some garbage on its output.  It is almost as if the data is misaligned.   Are there any register settings to force the PCI-6733 to reset?

Please see the following pictures:

working
not working

DAC0 - yellow
DAC1 - blue

Any help will be greatly appreciated,
Greg

[AlanArmstead]

Yeah, that is some wierd behavior.  As you probably noticed, there aren't any registers for 'resetting' the AO chip on that board.  There are, however, registers that reset the STC chip, but you probably aren't even using the STC if you are using immediate mode.  If you're not doing this already, you could try explicitly setting your ao channel to be in immediate mode, using the AO Immediate Register (offset 0x11) at the beginning of your program.  As a long shot, you could reset the STC.

-Alan A.