REMOTE OPERATION
Command Syntax
7/01 LDC-3700 Series 51
CHAPTER 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 47 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 *WAI (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.
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