AMETEK Lx Series II Programming Manual - Manual (Page 165)

Programming Manual Lx \ Ls Series II
161
7.9 SCPI Command Completion
SCPI commands sent to the AC source are processed either sequentially or in parallel. Sequential
commands finish execution before a subsequent command begins. Parallel commands allow
other commands to begin executing while the parallel command is still executing. Commands that
affect list and trigger actions are among the parallel commands.
The *WAI, *OPC, and *OPC? common commands provide different ways of indicating when all
transmitted commands, including any parallel ones, have completed their operations. The syntax
and parameters for these commands are described in chapter 4. Some practical considerations
for using these commands are as follows:
*WAI This prevents the AC source from processing subsequent commands
until all pending operations are completed.
*OPC? This places a 1 in the Output Queue when all pending operations have
completed. Because it requires your program to read the returned value
before executing the next program statement, *OPC? can be used to
cause the controller to wait for commands to complete before proceeding
with its program.
*OPC This sets the OPC status bit when all pending operations have
completed. Since your program can read this status bit on an interrupt
basis, *OPC allows subsequent commands to be executed.