The following program example shows a typical setup:
OUTPUT 707;":ACQUIRE:TYPE GLITCH"<terminator>
OUTPUT 707;":WAVEFORM:SOURCE LCHAN0_15"<terminator>
OUTPUT 707;":WAVEFORM:FORMAT BYTE"<terminator>
OUTPUT 707;":WAVEFORM:POINTS 512"<terminator>
OUTPUT 707;":DIGITIZE"<terminator>
OUTPUT 707;":WAVEFORM:PREAMBLE?"<terminator>
GOSUB Read_Preamble
OUTPUT 707;":WAVEFORM:DATA?"<terminator>
GOSUB Read_WaveData
This setup places the instrument into glitch mode, so there will be 2048
samples available. This means that when the :DIGitize command is received,
the command will execute until all 2048 samples have been acquired. Here,
however, the number of waveform points to be returned to the controller
(upon a :WAVeform:DATA? query) is set to 512. This must always be an
integer divisor of the number of samples available. The data for all 16
channels will be returned (:WAVeform:SOURce), in byte format
(:WAVeform:FORMat).
The :WAVeform:PREamble? query returns the parameters of the acquired
data, including the acquisition mode, number of points, and time interval
between samples. These parameters are important for interpreting the data
returned by the :WAVeform:DATA? query.
After receiving the ::WAVeform:DATA? query, the instrument will start
passing the waveform information when addressed to talk. The digitized
waveforms are passed from the instrument to the controller by sending a
numerical representation of each digitized point. The format of the numerical
representation is controlled with the ::WAVeform:FORMat command and may
be selected as BYTE or WWORD. The :WAVeform:BYTeorder command
specifies whether the data should be sent MSB first or LSB first when WORD
is the selected format.
The amount of data returned by the :WAVeform:DATA query depends on
how many channels are selected to return data (the :WAVeform:SOURce
command), whether the data is returned in byte or word format (the
:WAVeform:FORMat command), and whether the acquisition was performed
in glitch or normal mode (the :ACQuire:TYPE command).
The easiest method of transferring a digitized waveform depends on data
structures, formatting available, and I/O capabilities.
For more information, see the waveform subsystem commands and
corresponding program code examples in the online
HP 54620A/C
Programmer’s Reference
.
Programming Getting Started
Using the :DIGitize command
29
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