IEEE-488 Reference
4-27
After the second statement is executed, the instrument’s front
panel controls are locked out, including the LOCAL key.
To restore front panel operation after asserting LLO, as in the
following example, enter:
LOCAL 7
4.8.4 GTL (go to local) and local
The GTL command is used to take the instrument out of the
remote state. Operation of the front panel keys will also be
restored by GTL unless LLO is in effect. To cancel LLO, you
must set REN false.
Programming example Place the instrument in the re-
mote state with the following statement:
REMOTE 716
Now send GTL with the following statement:
LOCAL 716
Note that the instrument goes into the local state, and that op-
eration of the front panel keys has now been restored (assum-
ing that LLO is not in effect).
4.8.5 DCL (device clear)
The DCL command may be used to clear the IEEE GPIB in-
terface and return it to a known state. Note that the DCL
command is not an addressed command, so all instruments
equipped to implement DCL will do so simultaneously.
When the Model 2001 receives a DCL command, it will
clear the Input Buffer and Output Queue, cancel deferred
commands, and clear any command that prevents the pro-
cessing of any other device command. A DCL will not affect
instrument settings and stored data.
Programming example Use the following statement to
perform a DCL:
CLEAR 7
When the RETURN key is pressed, the instrument will per-
form the DCL.
4.8.6 SDC (selective device clear)
The SDC command is an addressed command that performs
essentially the same function as the DCL command. Howev-
er, since each device must be individually addressed, the
SDC command provides a method to clear only selected in-
struments instead of clearing all instruments simultaneously,
as is the case with DCL.
Programming example Use the following statement to
perform an SDC:
CLEAR 716
This sends the following IEEE-488 commands: UNT UNL
LISTEN 16 SDC. When the statement is executed, the in-
strument performs the SDC.
4.8.7 GET (group execute trigger)
GET is a GPIB trigger that is used as an arm, scan and/or
measure event to control operation. The Model 2001 will re-
act to this trigger if it is the programmed control source. GET
can also be used as the pre-trigger for the reading buffer. The
control source is programmed from the SCPI :TRIGger sub-
system (see paragraph 4.24).
With the instrument programmed and waiting for a GPIB
trigger, the following programming statement will provide
the GET:
TRIGGER 716
This sends IEEE-488 commands UNT UNL LISTEN 16
GET. When the ENTER key is pressed, the trigger event oc-
curs. (The command TRIGGER 7 just sends GET. Any oth-
er listeners are triggered when the ENTER key is pressed.)
4.8.8 SPE, SPD (serial polling)
The serial polling sequence is used to obtain the Model 2001
serial poll byte. The serial poll byte contains important infor-
mation about internal functions, as described in paragraph
4.6.9. Generally, the serial polling sequence is used by the
controller to determine which of several instruments has re-
quested service with the SRQ line. However, the serial poll-
ing sequence may be performed at any time to obtain the
status byte from the Model 2001.
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