How Can I Achieve Full Accuracy With My SCXI-1141/2/3 Module?Hardware: SCXI>>Modules>>SCXI-1141, SCXI>>Modules>>SCXI-1142, SCXI>>Modules>>SCXI-1143
Problem: I want to maximize the accuracy of my SCXI-1141/2/3 module? In the specifications for the module, next to the offset error it says that it can be calibrated out, so how can I calibrate out my offset error? Solution: The SCXI-1141/2/3 modules store calibration constants for gain adjustment, but they do not store any calibration constants for the offset adjustment. So, the offset error of a new SCXI-1141/2/3 module can vary considerably, and can often be relatively large. The modules have the capability of internally grounding each channel, so in order to achieve full accuracy from your measurements, you should internally ground each of the channels and subtract the measured value from all future measurements. This will eliminate not only the offset error associated with the SCXI-1141/2/3 module, but it will also account for offset errors introduced by the cabling and the DAQ device. Enabling Auto Zero in DAQmx In order to account for the offset error in DAQmx, you must set the Auto Zero Mode of your task to "Once". DAQmx will automatically ground the channels in your task and subtract the measured value from all of your future measurements.
Traditional DAQ is much more complex, so you should refer to the example program linked below for auto zeroing measurements in LabVIEW. For details on auto zeroing your measurements in C you should refer to the validation section of the SCXI-1141/2/3 Calibration Procedure which is also linked below. Related Links: Developer Zone Example: SCXI-114x Auto-Zero with DAQmx and Traditional DAQ (Legacy) Attachments:
Report Date: 09/30/2005 Last Updated: 09/25/2007 Document ID: 3PTG3M2G |
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