information about cooling, refer to the
Maintain Forced-Air Cooling Note to Users
.
•
Allow a warm-up time of at least 30 minutes after the chassis is powered on and NI-
DCPower is loaded and recognizes the NI 4141. The warm-up time ensures that the
NI 4141 and test instrumentation are at a stable operating temperature.
•
Use shielded copper wire for all cable connections to the device. Use twisted-pair wire to
eliminate noise and thermal offsets.
•
To ensure the system has had adequate time to settle, wait one second after requesting a
new current or voltage or after changing a load before taking a measurement.
•
Keep relative humidity between 10% and 70%, noncondensing.
•
Recalculate the test limits if they differ from the newest device specifications. Test limits
in this document are based on the July 2013 edition of the
NI PXIe-4141 Specifications
.
•
When making measurements, set the
niDCPower Aperture Time
property or
NIDCPOWER_ATTR_APERTURE_TIME
attribute to 2 power-line cycles (PLCs) on the
device. Set the
niDCPower Aperture Time Units
property or
NIDCPOWER_ATTR_APERTURE_TIME_UNITS
to power line cycles.
•
Do not use the NI-DCPower Soft Front Panel (SFP) to request test points for any
adjustment functions because you cannot set aperture time using the SFP.
•
Ensure that properties or attributes for the device that are not specified in calibration
procedures are set to their default values.
•
When making measurements, configure any specified digital multimeters (DMMs) with
the best available levels and limits for each specified test point.
Temperature conditions specific to verification procedures:
•
Maintain an ambient temperature of 23 °C ± 5 °C. Maintain an internal device
temperature range of T
cal
± 1 °C.
2
Temperature conditions specific to adjustment procedures:
•
Maintain an ambient temperature of 23 °C ± 1 °C. The NI 4141 internal temperature will
be greater than the ambient temperature.
Calibration Overview
Calibration includes the steps shown in the following figure.
2
T
cal
is the internal device temperature recorded by the NI 4141 at the completion of the last self-
calibration. Call the niDCPower Get Self Cal Last Temp VI to query T
cal
from the NI 4141.
4
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NI PXIe-4141 Calibration Procedure
