Sets the measurement reading rate in terms of Number of Power Line Cycles.
CalRefDmmSetReadingRate (hHandle, dReadingRate, plStatus)
Name |
Type |
Comments |
hHandle |
LONG |
Handle for a DMM. |
dReadingRate |
DOUBLE |
DMM reading rate in terms of Number of Power Line Cycles (NPLC). |
plStatus |
PLONG |
Returned status: 0 on success, negative number on failure. |
The reading rate is expressed in terms of Number of Power Line Cycles (NPLC). The Number of Power Line Cycles (NPLC) indicates how long a signal is integrated to obtain a single measurement. Noise introduced from the power line tends to be periodic. If the A/D converter integrates for an amount of time equal to one cycle of the power line noise, then the signal components from the periodic noise can be canceled. Generally speaking, the longer a signal is integrated by the A/D converter, the more accurate the reading results.
For 60Hz power, a DMM operating at 1 NPLC can report a new reading every 16.67 mSec. For 50Hz power and 1 NPLC, a new value can be reported every 20 mSec.
The reading rate can be a fraction of a power line cycle, e.g. reading rate can be set to 0.1 Line Cycles which would represent approximately 0.00167 seconds per reading if the Power Line Frequency is 60Hz.
The following sets the DMM reading rate to 0.5 Power Line Cycles:
LONG lHandle, lStatus;
CalRefDmmSetReadingRate (lHandle, 0.5, &lStatus);
CalRefDmmMeasure, CalRefDmmSetRange, CalRefDmmSetResolution, CalRefGetError