Stanford Research Systems SR865 Operation Manual page 159

Chapter 4
STREAMCH?
STREAMRATEMAX?
The
STREAMRATEMAX?
current time constant and sync filter period) in Hz. This is a query only command.
The streaming rate sets how often data points are streamed to the ethernet interface. All
streamed parameters are sampled at the same rate (and at the same times).The maximum
streaming rate is determined by the time constant of the SR865. Shorter time constants
allow faster streaming rates, and if sync filter is on, shorter sync filter periods allow faster
streaming rates, up to a limit of 1.25 MHz. The actual streaming rate can be set to the
maximum allowed rate divided by factors of 2.
Example
STREAMRATEMAX?
STREAMRATE(?) { n }
The STREAMRATE n
. The value of n is limited to 0 ≤ n ≤ 20. Set n=0 for the maximum streaming rate.
n
2
For example, if
streaming rate to (78125)/(2
The
STREAMRATE?
Example
STREAMRATE 4
STREAMRATE?
STREAMFMT(?) { i }
The
STREAMFMT i
Float32 requires 4 bytes per data point and int16 requires 2 bytes per point. Float32 will
use twice the ethernet bandwidth at the same streaming rate as int16.
Int16 values range from −32768 to +32767 where the sensitivity (divided by the expand)
is the value 31000.
Example
STREAMFMT 0
STREAMFMT?
STREAMPCKT(?) { i }
The
STREAMPCKT i
(i=1), 256 (i=2) or 128 (i=3) bytes.
Example
STREAMPCKT 0
Returns the stream configuration i
query returns the maximum allowed streaming rate (at the
Returns the maximum streaming rate in Hz
command sets the streaming rate to the maximum rate divided by
returns 78125, then
STREAMRATEMAX?
4
) = 4882.8125 Hz.
query returns the value n.
Sets the streaming rate to the max rate divided by 2
Returns the streaming rate n
command sets the stream data format to float32 (i=0) or int16 (i=1).
Sets the streaming format to float32 (4 bytes per point)
Returns the streaming format i
command sets the ethernet stream packet size to 1024 (i=0), 512
Sets the ethernet streaming packet size to 1024 bytes
Programming
will set the
STREAMRATE 4
4
SR865 DSP Lock-in Amplifier
141