Keithley 6514, Instruction Manual

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Remote Operation 12-9
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. Model 6514 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 the
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 command
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 Model 6514 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 com-
mand 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. Model 6514 reacts to this
trigger if it is the programmed control source. The control source is programmed from the SCPI
TRIGger subsystem.
SPE, SPD (serial polling)
Use the serial polling sequence to obtain Model 6514 serial poll byte. The serial poll byte con-
tains important information about internal functions. Generally, the serial polling sequence is
used by the controller to determine which of several instruments has requested service with the
SRQ line. However, the serial polling sequence may be performed at any time to obtain the status
byte from Model 6514.