Tutorial
Measurement (SEQuence3: ACQuire)
PCR-M/PCR-LE/PCR-LE2 has five different trigger subsystems -TRANsient, SYNChronize, ACQuire, SIMulation, and PROGram. These features are mapped to SEQuence1 to SEQuence5 respectively, as the SCPI specification generally categorizes each trigger subsystem as a numbered Trigger Sequence.
The SEQuence3 (ACQuire) group is the measurement trigger subsystem. This subsystem is used to measure values such as voltage, current, and power.
There are easy measurements and advanced measurements.
Easy Measurement
The PCR-M/ PCR-LE/PCR-LE2 has the capability to return voltage, current, and power measurement values. The easiest way is use the MEASure commands.
The MEASure commands immediately start a new measurement. This is the easiest way to make measurements, however simultaneity for multi-item measurements are lost, because each MEASure command starts a new measurement. To avoid this, consider the advanced measurement approach that is described later in this manual, allowing separate control for measurement initiation and data query.
Voltage/Current Measurement
In AC mode, use the AC measurement queries.
:MEASure:VOLTage:AC? 'Queries AC voltage in volts-rms
:MEASure:CURRent:AC? 'Queries AC current in amps-rms
In DC mode, use the DC measurement queries.
:MEASure:VOLTage:DC? 'Queries DC voltage in volts
:MEASure:CURRent:DC? 'Queries DC current in amps
The current measurement function also has the following additional items:
:MEASure:CURRent:AMPLitude:MAXimum? 'Queries peak current in amps
:MEASure:CURRent:AMPLitude:MAXimum:HOLD? 'Queries peak current (the held value)
:MEASure:CURRent:CREStfactor? 'Queries crest factor
The MEASure:CURRent:AMPLitude:MAXimum:HOLD command queries the maximum peak current since the PCR-M/ PCR-LE/PCR-LE2 was turned on or since it was explicitly cleared. To clear the peak current (held value), use the SENSe:CURRent:PEAK:CLEar command.
By *RST and *RCL default, the peak current (held value) is not cleared.
Available measurement items vary depending on the selected output mode. For example, DC measurement cannot be performed while AC mode is selected.
Peak current measurement and peak hold measurement can be performed in either AC or DC output mode.
Normally, it takes approximately 330 ms on the PCR-M and approximately 110 ms on the PCR-LE/PCR-LE2 to complete a single measurement. This means that sending MEASure queries multiple times requires long data acquisition time. If you want to acquire multiple items, it is recommended that you use the advanced approach described later.
The PCR-M/ PCR-LE/PCR-LE2 supports READ commands that also initiate a new measurement and data query, however, READ and MEASure operate exactly the same, as they are aliases.
Power Measurement
In AC mode, use the AC measurement queries.
:MEASure:POWer:AC? 'Queries AC real power in watts
:MEASure:POWer:AC:APParent? 'Queries AC apparent power in volt-amps
:MEASure:POWer:AC:REACtive? 'Queries AC reactive power in volt-amps-reactive
:MEASure:POWer:AC:PFACtor? 'Queries AC power factor
In DC mode, use the DC measurement queries.
:MEASure:POWer:DC? 'Queries DC power in watts
Advanced Measurement
In advanced measurement, you can separate and control the starting of measurement and the referencing of data.
State
The three states are available in the sequence operation. -> See for details
Voltage/Current/Power Measurement
To start a new measurement, set the trigger source to IMMediate and use the INITiate command.
:TRIGger:SEQuence3:SOURce IMMediate 'Selects trigger source to IMMediate
:INITiate:SEQuence3 'Initiates sequence 3
If you want the sequence 3 group to start the measurement on a software trigger, change the trigger source to BUS.
:TRIGger:SEQuence3:SOURce BUS 'Selects trigger source to BUS
:INITiate:SEQuence3 'Initiates sequence 3
:TRIGger:SEQuence3 'Applies a software trigger to sequence 3
When the measurement is completed, measurement data can be queried with the FETCh query commands.
:FETCh:VOLTage:AC? 'Queries AC voltage in volts, without new measure
:FETCh:CURRent:AC? 'Queries AC current in amps, without new measure
:FETCh:POWer:AC? 'Queries AC real power in watts, without new measure
:FETCh:POWer:AC:APParent? 'Queries AC apparent power in volt-amps, without new measure
If you send a FETCh command before the measurement is complete, correct measurement data will not be obtained. By using the *OPC command, you can obtain correct measurement data. ->See for detail
:INITiate:SEQuence3；*OPC 'Initiate sequence 3 and wait for the measurement to complete.
The TRIGger:SEQuence3:SOURce command sets the trigger source to BUS or IMMediate. The INITiate:SEQuence3 command makes the trigger subsystem leave the IDLE state and go the initiated state.
When the Trigger Source is set to IMMediate, the action is executed immediately causing a new measurement to start. When the Trigger Source is set to BUS, the trigger subsystem goes to the WTG (Waiting For Trigger) state. When a software trigger is applied with the TRIGger:SEQuence3:IMMediate or *TRG command, the measurement action is executed. When the operation is completed, the trigger subsystem returns to the IDLE state again. When an ABORt or an equivalent command is sent without executing the trigger, the measurement action is cancelled, and then the trigger subsystem returns to the IDLE state.
The ABORt command and IEEE488.1 sdc/dcl commands simply abort the measurement task that is in progress. It does not have a feature to invalidate any measurement data that has been acquired. On the other hand, the *RST and *RCL commands not only abort the measurement task, but also invalidate the acquired measurement data. This means that the "*RST;:FETC:VOLT:AC?" command line will generate an error, because no measurement data can be fetched and there is no new measurement is scheduled.
The only difference between MEASure and FETCh commands is that the MEASure command starts a new measurement while the FETCh command does not. Availability for measurement items varies depending on the output mode, but it is exactly the same for MEASure and FETCh.
AC Power Supply PCR-LE series