Measurement (sequence 3: ACQuire)
The PAT-T has the capability to return voltage and current measurement values. The easiest way is use the MEASure commands. The trigger function is not used.
The MEASure commands immediately start a new measurement. Simultaneity for multi-item measurements are lost, because each MEASure command starts a new measurement. Advanced measurement allows separate control for measurement initiation and data query.
To measure the voltage and current, use the following queries.
:MEASure:VOLTage? 'Query the voltage output
:MEASure:CURRent? 'Query the current output
The PAT-T also supports the READ command that initiates a new measurement and queries the data. READ and MEASure are aliases; they operate exactly the same.
The TRIGger:SEQuence3 (or TRIGger:ACQuire) subsystem allows you to control the start of the measurement and the data query separately.
To start a new measurement, set the trigger source to IMMediate and use the INITiate command.
:TRIGger:SEQuence3:SOURce IMMediate 'Set the trigger source to IMM
:INITiate:SEQuence3 'Initiate sequence 3
If you want the measurement of the sequence3 group to start on a software trigger, change the trigger source to BUS.
:TRIGger:SEQuence3:SOURce BUS 'Set the trigger source to BUS
:INITiate:SEQuence3 'Initiate sequence 3
:TRIGger:SEQuence3 'Apply a software trigger to sequence 3
When the measurement is completed, measurement data can be queried with the FETCh query commands.
:FETCh:VOLTage? 'Query the voltage output
:FETCh:CURRent? 'Query the current output
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. If the trigger source is set to IMMediate, the measurement starts immediately. 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 or *TRG common command, the measurement action is executed. 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 common commands not only abort the measurement task, but also invalidate the acquired measurement data. This means that the "*RST;:FETC:VOLT?" command will generate an error, because no measurement data can be fetched and there is no new measurement is scheduled.
The only difference between MEASure (or READ) and FETCh commands is that the MEASure command starts a new measurement while the FETCh command does not. Availability for measurement items is exactly the same for MEASure and FETCh.
The measurement data is stored in the measurement data cache for the mean value of the moving average deviations of 64 times measured in every 4 ms. The mean value of the moving average returns after 4 ms counted from the measurement begins upon receipt of the "INIT:SEQ3" command. Despite the setting of the "INIT:CONT:SEQ3" whether on or off, it will start the measurement in every 4 ms and display the mean value of the moving average deviations of 64 times.
The "INIT:SEQ3/INIT:NAME ACQ" command is a command that invalidates the current measurement data stored in the present measurement data cache and it begins a new measurement. The new measurement data will be established after 4 ms.
The "SENSe:AVERage:CLEar" command clears the measurement data stored in the cache and it does not return the query of "FETC" command until the moving average of 64 times is established. This "SENSe:AVERage:CLEar" command is a command that clears all the measurement data of the mean value of the moving average deviations of 64 times as when the setting of the voltage or the current value changes frequently or to change rapidly to be monitored. Therefore, after transmitting the command, new moving average of another deviations of 64 times will be generated after 256 ms.
To keep the trigger subsystem initiated for multiple actions without having to send an initiate command for each trigger, use the CONTinuous option. This enables measurement data to be automatically refreshed as if the PAT-T is operating in local mode.
If the auto continue mode is on, measurement data and the front panel displays are automatically refreshed by the internal trigger loop. In this state, MEASure/READ/FECh query commands work equivalently. New measurements are automatically repeated. This means that sending multiple FETCh queries results in different measurement results, and simultaneity is lost. When the continuous operation is enabled, the ABORt command is ignored because the trigger subsystem automatically exits the IDLE state even if it is aborted.
The *RST command sets CONTinuous to OFF.
Waiting for operation complete
The *OPC common command has a capability to wait for an operation to complete. In case the output on/off delay function is in used, the command will take the delay time (up to 10 s) which is set by this function.
When the *OPC command is sent, the PAT-T goes to Operation Complete Command Active State (OCAS). When the measurement is completed and there is no other operation pending, the PAT-T returns to Operation Complete Command Idle State (OCIS) and sets the OPC bit (bit 0) of the Standard Event Status Register to TRUE (1). This information can be confirmed with the OPC bit (bit 0) of the *ESR? query.
The following example starts the output on/off delay action and sends the *OPC command. When the measurement is completed, an SRQ (Service Request) is generated, as the Standard Event Status Enable Register and the Service Request Enable Register are unmasked so that an SRQ is signaled when the delay action completes.
*ESE 1;*SRE 32;*CLS;:INITiate:SEQuence2;*TRG;*OPC
Using the *OPC? query command instead of the *OPC command makes the PAT-T go to Operation Complete Query Active State (OQAS). When the measurement is completed and there is no other operation pending, the PAT-T returns to Operation Complete Query Idle State (OQIS) and sets a response data "1" (in NR1 format ) in the output queue.
At power-on or when the IEEE488 sdc/dcl or *RST command is received, the PAT-T is in the OCIS and OQIS state.
|When using the RS232C interface, the SRQ function cannot be used. However, the MSS bit of the *STB query can be used in the same manner as the SRQ function.|