9-8
Remote Operation
Model 6487 Reference Manual
IFC (interface clear)
The IFC command is sent by the controller to place all instruments on the bus in the local,
talker, listener idle states. The Model 6487 responds to the IFC command by canceling
front panel TALK or LSTN lights, if the instrument was previously placed in one of those
states. Note that this command does not affect the status of the instrument; settings, data,
and event registers are not changed.
To send the IFC command, the controller must set the IFC line true for a minimum of
100µs.
LLO (local lockout)
Use the LLO command to prevent local operation of the instrument. After the unit receives
LLO, all its front panel controls except the POWER are inoperative. In this state, pressing
LOCAL will not restore control to the front panel. The GTL command restores control to
the front panel.
GTL (go to local)
Use the GTL command to put a remote mode instrument into local mode. The GTL com-
mand also restores front panel key operation.
DCL (device clear)
Use the DCL command to clear the GPIB interface 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 6487 receives a DCL command, it clears the input buffer and output
queue, cancels deferred commands, and clears any command that prevents the processing
of any other device command. A DCL does not affect instrument settings and stored data.
SDC (selective device clear)
The SDC command is an addressed command that performs essentially the same function
as the DCL command. However, since each device must be individually addressed, the
SDC command provides a method to clear only selected instruments instead of clearing all
instruments simultaneously, as is the case with DCL.
GET (group execute trigger)
GET is a GPIB trigger that is used as an event to control operation. The Model 6487 reacts
to this trigger if it is the programmed control source. The control source is programmed
from the SCPI TRIGger subsystem.
