what's Auto Zero? and What kind of sensors need autozero?

[michenglaoxu]

I would like to know what kind of sensors needs AutoZero, how can we use DAQ MX to program it.

Any clue will be appreciated.

[Tom_W_[DE]]

HI michenglaoxu-

AutoZero mode is available on some SCXI modules and various modular instruments hardware (DMM's, etc).  It is usually used to provide a baseline DC offset determination for a measurement.  This is done by momentarily shorting the input channel of interest, taking several readings and averaging them to determine the effective DC input offset, and then subtracting this value from all subsequent readings in order to increase the accuracy of data.

Without knowing more about which hardware you're using, I'll suggest an SCXI example for LabVIEW that shows how autozero might be used with a measurement.  From the NI Example Finder (Help>>Find Examples) browse to Hardware Input and Output>>DAQmx>>Analog Measurements>>Temperature>>Cont Acq Thermocouple Samples-Int Clk.vi .  This section of the code, a single property node, is all that is required to enable AutoZero mode:

Hopefully this helps-

Message Edited by Tom W [DE] on 03-13-2006 06:48 PM