*WAI — Wait-to-Continue Prevent execution of commands until previous commands are
completed
Description
Two types of device commands exist:
• Sequential commands-A command whose operations are allowed to finish before the
next command is executed.
• Overlapped commands-A command that allows the execution of subsequent commands
while device operations of the Overlapped command are still in progress.
Use the *WAI command to suspend the execution of subsequent commands until the device
operations of all previous Overlapped commands are finished. The *WAI command is not need-
ed for Sequential commands.
The Model 2000 has three overlapped commands:
• :INITiate
• :INITiate:CONTinuous ON
• *TRG
Note: See *OPC, *OPC? and *TRG for more information.
The :INITiate commands remove the Model 2000 from the idle state. The device operations
of :INITiate are not considered complete until the Model 2000 returns to idle. By sending the
*WAI command after the :INITiate command, all subsequent commands will not execute until
the Model 2000 goes back into idle.
The *TRG command issues a bus trigger that could be used to provide the arm, scan, and
measure events for the Trigger Model. By sending the *WAI command after the *TRG com-
mand, subsequent commands will not executed until the pointer for the Trigger Model has fin-
ished moving in response to *TRG and has settled at its next state.
Program Fragment
PRINT #1, "output 02; :syst:pres" 'Select defaults
PRINT #1, "output 02; :init:cont off;:abort"
'Place 2000 in idle
PRINT #1, "output 02; :trig:coun 1;sour tim"
'Program for 30 measurements and
'then stop (idle)
PRINT #1, "output 02; :samp:coun 30"
PRINT #1, "output 02;:init; *wai" 'Start measurements and send *wai
PRINT #1, "output 02; :data?" 'Query a reading
PRINT #1, "enter 02" 'Get reading after 2000 goes into
idle
LINE INPUT #2, a$ 'Read the reading
PRINT a$ 'Display the reading
4-52 Remote Operation
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