set DAC range in MAX

[Dani Pindado]

Hello,
I have a current sensors which in the end is connected to a PCI-6221.
the range of the sensor is -50 to 50A, providing a voltage in range -10 to 10V.
 
the values I expect ro read are in range 0 to 30A.
 
I have created a nidaqmx global virtual channel using automation explorer (MAX), and the channel is linked to a nidaqmx scale.
 
in my software (LabVIEW) i do not create a task, but directly connect the virtual channel to "daqmx start task.vi"
 
my question is: does nidaqmx configure the hardware (setting DAC limits), so that the whole resolution of the card (16bits) is used just in the configured range 0-30A(0-3V)? or do I have to do it myself with a channel property node?
 
thank you in advance

[PelleS]

Hi,

The board amplifies the signal depending on your range setting up to -10 to 10 V in order to have the possibility to use the resolution more effeciently independent of the signal strength. Your card has four gain levels. The signal is then scaled back to the initial level. So let say that your signal is between -1 to 1 V. If you have the range set to -10 to 10 V no conditioning takes place and therefore you are not using all bits of resolution for your signal. So it is up you to set the appropriate range in the virtual channel.

Notice that the range should be adjusted to fit the signal after scaling.

Message Edited by Pelle S on 10-23-2007 07:59 AM

[Dani Pindado]

Hello Pelle,

thank you for your answer.

so: setting the range in MAX is enough if I want that the board uses the most efficient resolution, right? I do not have to configure it in Labview, if I set up the range if MAX, do I?

Mensaje editado por Dani Pindado

[PelleS]

Hi Dani,

You are correct. As long as you use the virtual channel specified in MAX. But if you create a new task in LabVIEW you need to specify the range there.