AMETEK Lx Series II Programming Manual - Manual (Page 49)

Programming Manual Lx \ Ls Series II
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4.8 Array Measurement Subsystem
This subsystem lets you retrieve arrays containing measurements data. Only current and
voltage measurements are stored in an array. Two measurement commands are available:
MEASure and FETCh. MEASure triggers the acquisition of new data before returning the
readings from the array. FETCh returns previously acquired data from the array.
Individual outputs of a three-phase source are specified by the setting of
INSTrument:NSELect.
Subsystem Syntax
MEASure | FETCh
:ARRay
:CURRent
[:DC]? Returns the digitized instantaneous current
:HARMonic
[:AMPLitude]? Returns amplitudes of the first 50 harmonics
:PHASe? Returns phase angles of the first 50 harmonics
:MODE Selects waveform data transfer format
:NEUTral
[:DC]? Returns the neutral digitized instantaneous current (3-
phase only)
:HARMonic
[:AMPLitude]? Returns neutral current harmonic amplitude
:PHASe? Returns neutral current harmonic phase
:VOLTage
[:DC]? Returns the digitized instantaneous voltage
:HARMonic
[:AMPLitude]? Returns amplitudes of the first 50 harmonics
:PHASe? Returns phase angles of the first 50 harmonics
MEASure:ARRay:CURRent?
FETCh:ARRay:CURRent?
Phase Selectable
These queries return an array containing the instantaneous output current in amperes. The data
returned in arbitrary block data format as follows:
#5.....
where b0,b1,b2,b3 are four hex bytes represent IEEE single precision floating number, where b0
is the most significant byte and b3 is the least significant byte. The number of bytes returned is
contained in the data block header
which always starts with the “#” pound character followed by a
single decimal character indicating the number of digits that make up the block length of the data.
Thus, “#516384…” indicates that there are 5 digits that follow containing the number of bytes in
the data block (excluding the header and length information). The actual number of bytes in this
case is 16384 or 16Kbytes.
The output voltage and current are digitized whenever a measure command is given or whenever
an acquisition trigger occurs. The acquisition sampling time interval is set by
SENSe:SWEep:TINTerval, and the position of the trigger relative to the beginning of the data
buffer is determined by SENSe:SWEep:OFFSet:POINts.
This command has two optional parameters. The first one may be used to specify the number of
256 data sample blocks to transfer. Valid parameter values are from 1 through 16. The second
parameter may be used to specify the offset in number of 256 data sample blocks from which to