Remote Operation
Publication 31470-001, Rev C, November 2, 2017
3-37
The following commands are duplicates of those given in Section 3.2.14, Instrument Triggering, and are shown
here for convenience. These commands must be used with GPIB BURSt and GPIB SWIFt modes of operation.
TRIGger:MODE
Syntax:
TRIGger:MODE
space
<burst mode data gathering POST trigger receipt or PRE trigger receipt
>
Example:
TRIG:MODE POST
! SETS THE BURST MODE DATA COLLECTION RELATIVE TO
! THE TIMING OF THE EVENT TRIGGER TO POST
Description:
This command is only for GPIB BURSt Mode measurements. Send this command only immediately after
CALC#:MODE BURS. TRIG:MODE controls the operation of the FIFO data buffer inside the power meter. When set
to POST, the burst of data points is taken after the receipt of a valid instrument trigger. When set to PRE, the burst
of data is assumed to be those data points that have arrived immediately preceding the valid instrument trigger
event. Using PRE requires some caution. The single processor in the 8650B is constantly performing data
acquisition. Sending any configuration commands while collecting the PRE trigger data can result in interrupted
timing of the data point collection.
TRIGger:DELay
Syntax:
TRIGger:DELay
space
<delay time between buffered readings in sec, 0.000 to 0.050>
Example:
TRIG:DEL 5E-3
! SETS THE BURST MODE MEASUREMENT TIME TO
! 5 mS BETWEEN MEASUREMENTS
Example 2:
TRIG:DEL 0
! SETS THE BURST MODE MEASUREMENT TO THE
! MAXIMUM MEASUREMENT RATE
Description:
This command applies only to the GPIB BURSt Mode. It sets the time interval between the measurements and is
accurate to approximately 5%. This is the only way to control the acquisition of individual data points in a burst
measurement. Burst measurement data is taken following or just prior to a single instrument trigger event. The
number of measurements taken is controlled by TRIGger:COUNt. Timing can be set in 0.001 second increments
from 0.000 to 0.050 seconds, inclusive. Setting this control to 0.000 activates the highest reading rate possible for
the particular measurement conditions.
Generally, if the acquisition of individual data points with controlling triggering is required, the GPIB SWIFt mode will
provide the highest measurement rates, with or without SRQ or hardware handshaking.
TRIGger:COUNt
Syntax:
TRIGger:COUNt
space
<number of data values to buffer in memory from 1 to 5000>
Example:
TRIG:COUN 100
! SETS THE BURST OR SWIFT MODE BUFFER READING TO 100
Description:
The power meter has an internal data buffer for storing measurement data until the slot 0 controller/resource
manager is ready to read the data. During the GPIB SWIFt or GPIB BURSt modes, this command controls the
number of power readings that are stored in the 8650B data buffer.
The value specified here applies to each individual channel. That is, if two sensors are attached and calibrated, the
8652B will perform the specified measurement and buffering for both channels. In the example shown above for this
command, that would be 100 points per channel.
The 8650B controls its gain ranges transparently by verifying internal range changes just before and just after
individual measurement points. If the internal range does not remain the same, the data point will be disgarded as
invalid. This can result in a successful GPIB BURSt Mode measurement with less measurement data than expected
according to the specified COUNt# parameter.
During GPIB BURSt mode, the COUNt# of readings will be taken with just one instrument trigger. During the GPIB
SWIFt mode however, individual instrument triggers are used to control the acquisition of individual data points.
When triggering is set to EXTernal, the power meter will perform one measurement each time it detects an external
TTL level signal. The value is then stored in the data buffer. This continues until the meter has received and
processed a COUNt# of triggers and also read in a COUNt# of data points to the buffer (as some data points may
be disgarded due to gain range conditions).
Содержание 8650B Series
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