Introduction; Interface Configuration; Remote Local - Stanford Research Systems SR124 Operation And Service Manual

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4.3 Introduction

4.3.1 Interface configuration
4.3.2 Buffers
4.3.3 Remote / local
Remote operation of the SR124 is through a simple command lan-
guage documented in this chapter. Both set and query forms of
most commands are supported, allowing the user complete control
of the lock-in from a remote computer through RS-232, or through
the optical fiber and the SX199 interface to GPIB, RS-232, or ethernet
interfaces.
Where applicable, the corresponding front-panel interface to each
command is also indicated. Most instrument settings are retained in
non-volatile memory. Upon power-on, these settings are restored to
their values before the power was turned o . Where appropriate, the
default value for parameters is listed in boldface in the command
descriptions.
Note that remote commanding does not function when the "Control
Inhibit" toggle switch is in the upper position.
Both RS-232 and optical fiber interfaces are fixed configuration, 9600
baud, 8-bit, with no parity or flow control.
The SR124 stores incoming bytes from the remote interfaces in sepa-
rate 128-byte input bu ers. Characters accumulate in the input bu er
until a command terminator ( CR or LF ) is received, at which point
the message is parsed and enqueued for execution. Query responses
from the SR124 are bu ered in interface-specific 256-byte output
queues. Queries are returned to the interface from which they were
received (RS-232 or optical).
If an input bu er overflows, then all data in the input bu er are
discarded, and an error is recorded in the ESR status register.
Any time the SR124 receives a remote command terminator ( CR
or LF ), the instrument transitions into the "Remote" state. When in
Remote (indicated by the REM annunciator in the Reference display
block), no keypad input or knob adjustment is allowed. To return to
front panel operation, press the [Recall] button (which also functions
as the "local" key).
Alternatively, the SR124 can be returned to Local mode by sending
the LOCL LOCAL command.
Remote Operation
SR124 Analog Lock-In Amplifier