Tutorial

Getting the Wave Data

You can use the WAVE query command to query the waveform data.

Specify the number of points of waveform data that you want to retrieve as a parameter of the query command.

WAVE? 10    'Query 10 points of waveform data.

At 38400 bit/s, it would take approximately 40 seconds to retrieve 10000 points.

While the data is being retrieved, "DATA TRANSFR" is displayed (no measured values are displayed). In this situation, you cannot perform panel operations. Because the data is being retrieved, integration continues.

For the response, the voltage and current values for the specified number of points of waveform data are returned in the following format.

Voltage coefficient<NR3>_current coefficient<NR3>,voltage value (hexadecimal)_current value (hexadecimal),. . .(the pattern is repeated for the specified number of points),END.

The interval between points is 10 µs.

The hexadecimal numbers are 16-bit signed integers.

For GPIB and USB, up to 256 characters can be returned as the response to a single query. If the data is longer than 256 characters, it is returned in the following format.

Voltage coefficient<NR3>_current coefficient<NR3>,voltage value (hexadecimal)_current value (hexadecimal),. . .(the pattern is repeated until the total data length is 256 characters),CONT.

To query the next block of data, send the same query with parameter "-1." In response to "WAVE? -1," the KPM1000 returns the voltage and current values for the next block of the waveform data in the following format.

If there are more blocks of data to be retrieved:

Voltage value_current value,voltage value_current value . . . (the pattern is repeated until the total data length is 256 characters), CONT.

If this is the last block of data to be retrieved:

Voltage value_current value, . . . (the pattern is repeated for the remaining points),END.

Continue sending "WAVE? -1" to query the waveform data until the response ends in "END."

 

 

As an example, assume that the KPM1000 returned the following response when it received the query "WAVE? 5."

+1.50E-02_ +1.00E-04,ffda_3e8,fffd_3ea,1c_3ed,32_3e6,55_3f3,END

 

First, convert the hexadecimal values into decimal values. The hexadecimal numbers are 16-bit signed integers. H7FFF is 32767. H8000 is -32768.

ffda_3e8 → -37, 1000

fffd_3ea → -2, 1002

1c_3ed → 28, 1005

32_3e6 → 50, 998

55_3f3 → 85, 1011

 

Next, multiply the converted decimal values by the voltage or current coefficient. The coefficients are in the first line of the response. The coefficients are determined by the ranges and the CT and PT values.

ffda_3e8 → -37, 1000 → -37*+1.50E-02 = -0.555 (voltage), 1000* +1.00E-04 = 0.1 (current)

fffd_3ea → -2, 1002 → -0.03, 0.1002

1c_3ed → 28, 1005 → 0.42, 0.1005

32_3e6 → 50, 998 → 0.75, 0.0998

55_3f3 → 85, 1011 → 1.275, 0.1011

 

Example of a voltage graph that was constructed by using the WAVE? query