Introduction; Interface Configuration; Buffers - Stanford Research Systems SR446 Operation And Service Manual

2.2 Introduction

2.2 Introduction

2.2.1 Interface Configuration

2.2.2 Buffers

SR446 400 MHz Programmable Gain Preamplifier
Remote operation of the SR446 400 MHz Programmable Gain Preamplifier
is through a simple command language documented in this chapter.
Both set and query forms of most commands are supported, allowing
the user complete control of the unit from a remote computer through
USB.
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 off. Where appropriate, the
default value for parameters is listed in
descriptions.
The USB interface is implemented as a serial port emulator, with fixed
data rate of 115,200 baud, 8 data bits, 1 stop bit, no parity, and no flow
control.
The indicator illuminates whenever a USB connection is active.
Connect
The indicator illuminates after a remote command error, and can
Error
be cleared by the STAT? query.
The SR446 stores incoming bytes from the remote interfaces in separate
500‑byte input buffers. Characters accumulate in the input buffer until
a command terminator (the ⟨ CR ⟩ byte) is received, at which point the
message is parsed and queued for execution. Query responses from the
SR446 are buffered an a 500‑byte output queue.
If the input buffer overflows, then bit 0 (unknown command) is typically
set in the STAT? register, the buffer is cleared, and the instrument
continues to process new commands.
boldface
in the command
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