Agilent 6800 Series Measurements

The built-in power analyzer capability offers many voltage, current, and power measurements to the user. While on, the ac power source/analyzers are continuously sampling instantaneous output volt- age and current for several output cycles and writ- ing the data to buffers. Each buffer, one for voltage and one for current, holds 4096 data points. The voltage and current data is used to calculate the requested measurement parameter. There are two basic methods to obtain a measurement: using the MEASure command or the FETCh command. These commands can return a single measured parameter, an array of voltage and current harmonic data, or an array of the 4096 voltage or current data values.

What is a MEASure Command?

When this command is sent to the 6800 series ac power source/analyzer, the unit begins acquir- ing new voltage and current data into its data buffers. Upon completing the acquisition of 4096 data points for voltage and current, the unit then

performs the required calculation to return the requested measurement parameter. When a new acquisition of instantaneous output voltage and current data is desired, this command should be used to return the requested measurement.

What is a FETCh Command?

This command allows the user to retrieve meas- ured parameters from previously acquired voltage and current data. For example, the FETCh com- mand can be used after a MEASure command to return calculated parameters from the same 4096 data points that were acquired by the MEASure command. In addition, the FETCh command can be used to retrieve measurement information after triggering an acquisition of digitized voltage and current data. This method provides the flexibility to synchronize the data acquisition with a triggered event, and then return many calculations from the existing voltage and current data buffers.

Pre-event and Post-event Acquisition Triggering