2.4 Commands
2 – 9
and reset. If a parameter bu
ff
er overflows, a command error will be
generated and the o
ff
ending command discarded.
Commands are terminated by either a semicolon, a
CR
(ASCII 13),
or a
LF
(ASCII 10). If the communications interface is GPIB, then
the terminating character may optionally be accompanied by an EOI
signal. If the EOI accompanies a character other than a
LF
, a
LF
will be appended to the command to terminate it. Execution of the
command does not begin until a command terminator is received.
White space is ignored.
Aside from communication errors, commands may fail due to either
syntax or execution errors. Syntax errors can be detected by looking
at bit 5 (CME) of the event status register (
*ESR?
). Execution errors
can be detected by looking at bit 4 (EXE) of the event status register.
In both cases, an error code, indicating the specific cause of the error,
is appended to the error queue. The error queue may be queried
with the
LERR?
command. Descriptions of all error codes can be
found in the section Error Codes, starting on page 2 – 25 .
2.4.1.1 Examples
Commands may be given with a simple example illustrating their
usage. In these examples, all data sent by the host computer to the
SR470 are set as
straight teletype font
, while responses received
the host computer from the SR470 are set as
slanted teletype font
.
The usage examples vary with respect to set
/
query, and optional
parameters. These examples are not exhaustive, but are intended to
provide a starting point for user programming.
SR470 Shutter Controller
