niDmm_Configure and resolution

[KingTermite]

I am updating an old handler for our NI Dmm devices.

One task is to make resolution configurable based on device.

Right now we have code that uses


niDmm_Configure() and for resolution it uses the NIDMM_VAL_5_5_DIGITS constant (which evauluates to 5.5). Some code examples (from NI) I see use this constant. The help shows that the default value is 0.00001 and some examples use values like that.


QUESTION1: How does the resolution get determined? Which form should I use?



I see that niDmm_Configure() is depricated and now its preferable to use niDmm_Configure_Measurement(). niDmm_Configure_Measurement() seems to drop the frequency arguments.

QUESTION2: Do I need to set the frequency ranges elsewhere? Is it determined automatically?

[Chris_K_]

Hi, KingTermite

It looks like you are using a pretty old version of the DMM driver.  I had to do quite a bit of research to find the functions you are talking about but it looks like niDmm_Configure() has been replaced with niDMM_ConfigureMeasurement, and then again it has been replaced again with more specific functions, the latest are  niDMM_ConfigureMeasurementDigits, and niDMM_ConfigureMeasurementAbsolute.  To answer your specific question, you use to respective function depending on how you want to specify the resolution. 

The resolution is either given in a Digits format (this would be the 5.5 you mentioned above) and an Absolute format.  Please see the Resolution topic in the Index of the help file for your version of NI-DMM.

For your second question, the frequency measurement is selected the NIDMM_ATTR_FUNCTION (set to NIDMM_VAL_FREQ), in the niDMM_ConfigureMeasurementDigits/Absolute() function, and the range is configured with niDMM_ConfigureFrequencyVoltageRange()

Again there is more information about these functions in the NI-DMM help. 

Chris_K

Message Edited by Chris_K_ on 02-14-2008 08:33 PM