ILX Lightwave LDC-3700C Series, Руководство пользователя, Страница: 77 / 176

R E M O T E O P E R A T I O N
Command Syntax
04_09 LDC-3700C Series
61
C H A P T E R
3

Command Timing
This section describes, for each device-dependent command, whether that
command is performed in an overlapped or sequential manner. In other words, it
states whether the next command may begin while this command is being
executed, or if the next command must wait until this command is completed
before its execution begins. See Operation Complete Definition on page 56 for
conditions about setting the operation complete flag.
Sequential/Overlapped Commands
All device-dependent commands are executed in an overlapped manner:
subsequent commands may begin before the current command is completed.
Some common commands are sequential; the next command must wait until this
command is completed. All device-dependent commands are executed in an
overlapped manner, except the "DELAY" command which is sequential. The
operation complete flag is set after the conditions outlined in the Operation
Complete Definition have been satisfied.
The 04_09 (common command) is an example of a sequential command which
forces the next command to wait until the no-operation-pending flag is true. This is
essentially the same as waiting for the OPC flag to become true, because the no-
operations-pending flag is used to set the OPC flag (bit 0 of the Standard Event
Status Register).
Commands which change the status of the instrument limits, or change its mode
or current range, step value, or status enable registers, will not have their OPC
flag set until all current writing to non-volatile memory has been completed. This
ensures the OPC flag is never set prematurely.
Query Response Timing
Query responses are evaluated at the time the query request is parsed, and not at
the time the response message is sent. In most cases this does not create a
problem since the time between parsing a query and sending its response is
small.