DAC Direct Addressing for M Series

Question

Hello,
I am writing drivers using register level access for the M series cards (particularly the 6259) and would like to directly access the DAC registers (ie., via the DAC_Direct_Data[i] registers) using immediate update mode. I have been unable to get them outputing a voltage.
I have the ddk examples, but I am unsure about the offsets for these registers and the corresponding AO_Config_Bank registers. Also, the mseries_registermap.doc does not contain these registers (in particular the register contents for the Config_Bank).
If you could point me in the direction of the register addresses and their contents I would much appreciate it.
Many thanks,
Ern

Answer 1

Hi Pennells-
The 6010 is indeed similar to a 622x in AI terms, but in AO it's quite different.  For AO, the 6010 uses the STCII general purpose PWM channels to create the AO data.  I haven't had time to create an example yet, but here are some notes that might help you get started.
Each AO channel uses two of the Gen_PWM instances defined in tMSeries.h.  For the sake of discussion, the PWM channels will be referred to upper and lower.  These are the PWM channel values for their corresponding AO channels:
AO 0
upper = 0
lower = 2
AO 1
upper = 1
lower = 3
The actual register values to write to these PWM channels are as follow (where 'value' represents a normal 16-bit binary value, i.e. not 2's complement):
upperPWMValue = ((value >> 7) & 0x1FF) + 256;
lowerPWMValue = ((value & 0x7F) * 1564) / 1000 + 768;
Hopefully this helps-
Tom W
National Instruments