Stanford Research Systems SR865A, Руководство по эксплуатации

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136 Programming Chapter 4
SR865A DSP Lock-in Amplifier
CAPTURELEN(?) { n }
The CAPTURELEN command sets or queries the capture buffer length. The value n is the
buffer length in kilobytes (256 total data points). For example, 32 k points of X and Y is
a total of 64 k data points (256 kbytes of buffer at 4 bytes/point) and a length of n=256.
32
k points of X, Y, R and θ require s twice as much or a length of n=512.
Since the internal blocks that make up the buffer are 2 kbytes each, the value of n must be
even and is limited to 1 ≤ n ≤ 4096
. If n is odd, then the buffer length will be set to n+1.
Example
CAPTURELEN 256 Sets the capture buffer length to 256 kbytes or 64 k total data
points
CAPTURELEN?
Returns the buffer length n (kbytes)
CAPTURECFG(?) { X | XY | RT | XYRT | i }
The
CAPTURECFG i
command sets the capture configuration to X (i=0), X and Y (i=1),
R and θ (i=2) or X, Y, R and θ (i=3
).
For a given buffer length (total data points), capturing more parameters results in fewer
points of each parameter and a shorter total capture time. The capture
rate is unaffected
by CAPTURECFG.
Example
CAPTURECFG 1 Capture X and Y
CAPTURECFG XY
CAPTURECFG?
Returns the capture configuration i
CAPTURERATEMAX?
The CAPTURERATEMAX? query returns the maximum allowed capture rate (at the
current time constant) in Hz. This is a query only command.
The actual capture rate can be this maximum rate or this rate divided by powers of 2.
Note that this maximum rate is dependent on the time constant and sync filter settings.
Example
CAPTURERATEMAX? Returns the maximum capture rate in Hz
CAPTURERATE(?) { n }
The CAPTURERATE n command sets the capture rate to the maximum rate divided by
2
n
. The value of n is limited to 0 ≤ n ≤ 20.
Set n=0 for the maximum capture rate.
For example, if
CAPTURERATEMAX?
returns 78125, then
CAPTURERATE 4
will set
the capture rate to (78125)/(2
4
) = 4882.8125 Hz. Note that if the time constant is
modified during a capture, the sampling rate will change mid-capture.