Keithley 2182, User Manual, Page: 288 / 339

E-4 Example Programs
One-shot triggering
Other voltmeters generally have two types of triggering: one-shot and continuous. In one-
shot, each activation of the selected trigger source causes one reading. In continuous, the
voltmeter is idle until the trigger source is activated, at which time it begins taking readings at a
specified rate. Typical trigger sources are:
• IEEE-488 talk
• IEEE-488 Group Execute Trigger (GET)
• "X" command
• External trigger (rear panel BNC)
Arming the instrument to respond to triggers is implicit in the non-SCPI voltmeters. Sending
a command to a non-SCPI voltmeter to change any of the trigger controls causes the instrument
to arm itself for triggers.
The SCPI trigger model implemented in the Model 2182 gives:
• Explicit control over the trigger source (the TRIGger subsystem).
• A way for completely disabling triggers.
Changing any of the settings in the TRIGger subsystem does not automatically arm the
Model 2182 for triggers.
The following program sets up the Model 2182 to take one reading each time it receives an
external trigger pulse.
'Example program to demonstrate one-shot external triggering
'For QuickBASIC 4.5 and CEC PC488 interface card
'Edit the following line to where the QuickBASIC
'libraries are on your computer
'$INCLUDE: 'c:\qb45\ieeeqb.bi'
'Initialize the CEC interface as address 21
CALL initialize(21, 0)
'Reset controls and put trigger model in IDLE state
CALL SEND(7, "*rst", status%)
CALL SEND(7, "trig:sour ext;coun inf", status%)
'start everything
CALL SEND(7, "init", status%)
After the Model 2182 receives the INITiate command, it stops at the control source in the
trigger model, waiting for a trigger pulse. Each time a pulse arrives at the Trigger Link
connector, the Model 2182 takes one reading. Because TRIGger:COUNt has been set to
INFinity, the instrument never enters the idle state. You can send the ABORt command to put
the instrument in the idle state, disabling triggers until another INITiate command is sent.