Stanford Research Systems SR844, User Manual

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4-24 Data Storage
SR844 RF Lock-In Amplifier
Data Storage Commands
SRAT(?){i}
The
SRAT
command sets or queries the Data Sample Rate. The parameter
i
selects the sample rate as shown below.
i sample rate i sample rate
0 62.5 mHz (16 s) 7 8 Hz
1 125 mHz (8 s) 8 16 Hz
2 250 mHz (4 s) 9 32 Hz
3 500 mHz (2 s) 10 64 Hz
4 1 Hz 11 128 Hz
5 2 Hz 12 256 Hz
6 4 Hz 13 512 Hz
14 Trigger
SEND(?){i}
The
SEND
command sets or queries the End of Scan mode. The parameter
i
selects one–shot (
0
) or loop (
1
). If loop mode is used, be sure to pause data
storage before reading the data to avoid confusion about which data point is most
recent.
TRIG
The
TRIG
command is the software trigger command. This command has the same
effect as a trigger at the rear panel TRIG IN. If the Data Sample Rate is set to
Trigger (
SRAT14
), then receipt of this command causes data to be sampled and
stored to both the Channel 1 and Channel 2 buffers within 2 ms (actually on the
next 512 Hz clock tick). The command is ignored if the Data Sample Rate is set to
an internal rate, or if the buffers are full, or if the command is received before a
previous
TRIG
command has completed.
TSTR(?){i}
The
TSTR
command sets or queries the Trigger Scan Mode to On (
1
) or Off (
0
).
When Trigger Scan Mode is On (
i=1
), an external or software trigger starts the
scan. This mode is only applicable for fixed data sample rates set by
SRAT
0-13
.
STRT
The
STRT
command starts or resumes data storage.
STRT
is ignored if storage is
already in progress.
PAUS
The
PAUS
command pauses data storage. If storage is already paused or reset
then this command is ignored.
REST
The
REST
command resets the data buffers. The
REST
command can be sent at
any time – any storage in progress, paused or not, will be reset. This command
will erase the data buffer!