E Series Calibration
Your device uses hardware calibration to adjust the analog circuitry. This calibration is done with calibration digital-to-analog converters, called calDACs, that fine-tune the analog circuitry. The calDACs must be programmed (or loaded) with certain numbers called calibration constants. Those constants are stored in nonvolatile memory (EEPROM) on your device or are maintained by NI-DAQmx. NI recommends that you self-calibrate your device just before a measurement session but after your computer and the device have been powered on and warmed up for at least 15 minutes. You should allow this same warm-up time before performing any calibration of your system. Frequent calibration produces the most stable and repeatable measurement performance. The device is not harmed in any way if you recalibrate it often.
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Note Calibrating your MIO or AI device takes some time. Do not be alarmed if the Self-Calibrate or Adjust E Series Calibration function/VI takes several seconds to execute. |
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Note For best results, stop any ongoing tasks and disconnect any unnecessary external connections before running calibration. |
Calibration Constant Loading by NI-DAQmx
NI-DAQmx automatically loads calibration constants into calDACs whenever you call functions/VIs that depend on them. The following conditions apply:
- 12-bit E Series devices
- 12-bit devices use a single set of calibration constants for both unipolar and bipolar modes of analog input.
- One set of constants is valid for unipolar, and another set is valid for bipolar configuration of the analog output channels. When you change the polarity of an analog output channel, NI-DAQmx reloads the calibration constants for that channel.
- 16-bit E Series devices
- Calibration constants required by the 16-bit E Series devices for unipolar analog input channels are different from those for bipolar analog input channels. If you are acquiring data from one channel, or if all of the channels you are acquiring data from are configured for the same polarity, NI-DAQmx selects the appropriate set of calibration constants for you. If you are scanning several channels, and you mix channels configured for unipolar and bipolar mode in your scan list, NI-DAQmx loads the calibration constants that correspond to the first channel in the scan list.
- NI 6025E devices use a single set of calibration constants for both unipolar and bipolar modes of analog input.
- One set of constants is valid for unipolar, and another set is valid for bipolar configuration of the analog output channels. When you change the polarity of an analog output channel, NI-DAQmx reloads the calibration constants for that channel.
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