Model 6487 Reference Manual
Triggering
7-11
B) INITiate, FETCh, and READ?
1.
After sending the INITiate command to take the instrument out of idle, the instru-
ment will perform one or more measurements and then return to idle. The FETCh?
command can then be used to read the last reading that was measured.
2.
If INITiate is sent while the instrument is operating within the trigger model, it will
not execute until the operation returns to the idle state.
3.
One alternative to using INITiate is to use the READ? command. When READ? is
sent, the instrument is taken out of idle and all readings that are taken are returned
(See
for details on READ?).
C) ARM:SOURce <name>
With the TIMer control source selected, use the ARM:TIMer command to set the timer
interval.
D) ARM:DIRection <name>
The source bypass can only be used if the TLINk control source is selected.
E) ARM:ILINe <NRf> and ARM:OLINe <NRf>
Input trigger and output trigger cannot share the same trigger link line. Defaults set line 1
as the input and line 2 as the output.
F) TRIGger:CLEar
When this action command is sent, any pending (latched) input triggers are cleared imme-
diately. When the picoammeter is being latched by another instrument, it may inadvert-
ently receive and latch input triggers that do not get executed. These pending triggers
could adversely affect subsequent operation.
When using external triggering, it is recommended that TRIGger:CLEar be sent after
sending the ABORt command and at the beginning of a program before sending a initiate
command. (See “INITiate” command.)
Programming example
The following command sequence will trigger and return 10 readings.
*RST
' Return 6487 to RST defaults.
ARM:SOUR IMM
' Set arm control source Immediate.
ARM:COUN 1
' Set arm count to 1.
TRIG:SOUR IMM
' Set trigger control source Immediate.
TRIG:COUN 10
' Set trigger count to 10.
SYST:ZCH OFF
' Disable zero check.
READ?
' Trigger and return 10 readings.
