|NI-DCPower (English | Japanese)|
The NI PXIe-4154 averages measurement samples to reduce noise and improve sensitivity. You can set the number of samples to average programmatically using the niDCPower Samples To Average property or the NIDCPOWER_ATTR_SAMPLES_TO_AVERAGE attribute.
Each channel of the NI PXIe-4154 has two analog-to-digital converters — one for the voltage, and one for the current — that are synchronized and run at 200 kS/s. The effective rate at which measurements are returned from the NI PXIe-4154 can vary depending on the setting of the niDCPower Samples To Average property or the NIDCPOWER_ATTR_SAMPLES_TO_AVERAGE attribute.
The default value of the niDCPower Samples To Average property and the NIDCPOWER_ATTR_SAMPLES_TO_AVERAGE attribute is 500 for the NI PXIe-4154. As expressed in the following equation, the NI PXIe-4154 can return up to 400 measurements per second using the default value:
If no measurement averaging is used (Samples To Average = 1), the NI PXIe-4154 returns 200,000 measurements per second when acquiring continuously.
While measuring without averaging yields the fastest measurement rate, noise from the environment increases measurement uncertainty. Adjust the niDCPower Samples To Average property or the NIDCPOWER_ATTR_SAMPLES_TO_AVERAGE attribute as necessary to optimize the noise performance and measurement rate for your application.
|Note Measurement rate refers only to the hardware measurement rate and does not include software latency.|
You can use the niDCPower Measure Record Delta Time property or NIDCPOWER_ATTR_MEASURE_RECORD_DELTA_TIME attribute to determine the period of time between two measurements in a record. This property can only be used when acquiring a record with a record length greater than one. The effective measurement rate of a record can be calculated by taking the inverse of the delta time. Refer to the Configuring the Measure Unit topic for more information.