Waveform data retrieval function
In the impedance measurement using the current interrupt method, the voltage and current are measured at 2 µs intervals for 100 ms from the start of the current interrupt. The voltage/current waveform data of this measurement can be read.
Set the impedance measurement method to current interrupt method, and set the pulse condition.
|METH CINT||'Set the impedance measurement method to current interrupt method.|
|IMP:CURR:PULS:WIDT 10E-3||'Set the pulse width to 10.0 ms.|
|IMP:CURR:PULS:DEPT:RAT 100||'Set the pulse depth to 100 %.|
|IMP:CURR:PULS:TRAN 0.01E-3||'Set the pulse transition time to 0.01 ms.|
If INIT:SEQ1:WAV is used to perform the impedance measurement, the measured voltage and current at 2 µs intervals for 100 ms from the start of the current interrupt are held.
|INIT:SEQ1:WAV;*OPC?||'Start the impedance measurement while holding the voltage and current waveform data, and wait for the measurement to complete.|
|(Read the response)|
Use TRAC? to retrieve the voltage/current waveform data that is held. Specify the data transmission/recording mode. Specify the start point and length of the data that is actually transmitted from the retrieved data.
The maximum number of waveform data values that can be retrieved using TRAC? is 1024. If the number of waveform data values exceeds 1024, the number of data values is compressed, so that it is within 1024.
|FORM:BORD NORM||'Set the transmission/recording mode to Big Endian.|
|FORM:PAGE:STAR 0||'Set the start point of the waveform data to be retrieved to 0 s.|
|FORM:PAGE:LENG 100E-3||'Set the length of the waveform data to be retrieved to 100 ms.|
|TRAC? VOLT||'Query the voltage waveform data.|
|TRAC? CURR||'Query the current waveform data.|
The response to TRAC? returns the waveform data in binary format.
Example of a TRAC? VOLT response (retrieve the voltage waveform consisting of 1024 values over 100 ms)
The four-digit number after #4 indicates the number of bytes of the subsequent binary data. The terminator is <LF>.
Time axis information of the waveform data
If the number of waveform data values to be retrieved is less than or equal to 1024, the measurement interval of 2 µs is the time axis information.
If the number of data values is greater than 1024, the data is compressed so that number of values is within 1024. When compressed, the value that divided the length of the waveform data by 1024 is the time axis information.
For waveform data over 100 ms, the data values are returned at approximately 97.6 µs intervals which can be calculated as follows: 100E-3/1024 = 9.76E-5. Thus, 1024 waveform data values at 97.6 µs intervals make up the waveform data over 100 ms.
The waveform data that is held is discarded if the impedance measurement condition such as the pulse condition of the current interrupt method is changed.
Voltage and current measurements cannot be performed while the waveform data is being held. Therefore, the low voltage alarm of the voltage sensing input cannot be detected. INIT:SEQ1 releases the waveform data that is held. Release the waveform data that is held after the waveform data is retrieved.