:MEASure:OSCilloscope:VRMS
Command Syntax
:MEASure:OSCilloscope:VRMS
Query Syntax
:MEASure:OSCilloscope:VRMS?
Description
Moves the VRMS measurement to the top of the Results table. This measurement is compatible with PAM4 signals over the entire display or region but not over a cycle. Displays the measurement if it is not already shown on the table. The query form of the command returns the measured value. VRMS is a measure of the AC or DC RMS of a pulse waveform, as specified by the TYPe child command. The measurement data is sampled across the entire displayed waveform or a single cycle, as specified with the AREa child command.
Sources can be any displayed waveform, waveform memory, or function. For example, CHAN1A, WMEMory1, or FUNCtion1. Use :MEASure:TBASe:METHod to change the definition of the waveform's top/base. Use :MEASure:THReshold:METHod to change the definition of the waveform's threshold.
This command is PAM4 compatible when it is made over the display or a region as determined by the :AREa child command. It is not PAM4 compatible when made over a cycle.
Measurement Ready?
To confirm that the measurement is ready to read, you can query the measurement's status:
if ('CORR' in Flex.query(':MEASure:OSCilloscope:VRMS:STATus?')):
measurement = Flex.query(':MEASure:OSCilloscope:VRMS?')
If averaging is turned on (:ACQuire:AVERaging), you can also confirm if the measurement result is ready by comparing the number of specified averages (:ACQuire:ECOunt?) versus the number of measurement sweeps that have occurred (:MEASure:OSCilloscope:VRMS:COUNt?). The technique uses the :COUNt? common measurement query. For example,
if (Flex.query(':MEASure:OSCilloscope:VRMS:COUNt?') >= Flex.query(':ACQuire:ECOUNt?')):
measurement = Flex.query(':MEASure:OSCilloscope:VRMS?')
You can also use an acquisition limit lest to test that a number of waveform samples, or pattern acquisitions have completed before returning a measurement. Refer to the :LTESt:ACQuire:CTYPe command.
Common Measurement Child Queries
This command supports the use of the following common measurement queries: :LOCation?, :COUNt?, :MAXimum?, :MINimum?, :MEAN?, and :SDEViation?.
Measurement Identification
Avoid subtle programming errors! To ensure that the correct measurement is installed or queried, always explicitly identify a measurement when installing a measurement or querying a measured value, status, or detail. To identify a measurement, specify the measurement's source waveform (:SOURce child command). With some measurements, you may also need to specify other identifying values. Generally, when selecting a measurement using FlexDCA's GUI, if a dialog appears prompting you to select values, you should explicitly specify these values when remotely identifying the measurement. More information.
For example, to return the status of the measurement, :MEASure:OSCilloscope:VRMS:
flex.write(':MEASure:OSCilloscope:VRMS:SOURce CHAN1A')
if flex.query(':MEASure:OSCilloscope:VRMS:STATus?') == 'CORR';
measurement = flex.query(':MEASure:OSCilloscope:VRMS?')
else:
details = flex.query(':MEASure:OSCilloscope:VRMS:STATus:DETails?')
reason = flex.query(':MEASure:OSCilloscope:VRMS:STATus:REASon?')
Child commands for measurement identification:
:MEASure:OSCilloscope:VRMS:SOURce:MEASure:OSCilloscope:VRMS:AREa:MEASure:OSCilloscope:VRMS:TYPe:MEASure:OSCilloscope:VRMS:REGion
Example Command Sequence
:SYSTem:MODE OSCilloscope :MEASure:OSCilloscope:VRMS:SOURce CHAN1A :MEASure:OSCilloscope:VRMS:AREa CYCLe :MEASure:OSCilloscope:VRMS:TYPe AC :MEASure:OSCilloscope:VRMS :MEASure:OSCilloscope:VRMS?