Llo (Local Lockout); Sdc (Selective Device Clear) - Keithley 2302 Instruction Manual

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 POWER are inoperative. In this state, pressing the
LOCAL key 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 the power supply 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. The power supply reacts
to this trigger if it is the programmed control source.
SPE, SPD (serial polling)
Use the serial polling sequence to obtain the power supply serial poll byte. The serial poll byte
contains 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 the power supply.
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GPIB Operation 7-7