Keithley 2303, User Manual

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6-4 GPIB Operation
General bus commands
General bus commands are those commands, such as DCL, that have the same general mean-
ing regardless of the instrument. Table 6-1 lists the general bus commands.
REN (remote enable)
The remote enable command is sent to the power supply by the controller to set up the instru-
ment for remote operation. Generally, the instrument should be placed in the remote mode
before you attempt to program it over the bus. Simply setting REN true does not actually place
the instrument in the remote state. You must address the instrument to listen after setting REN
true before it goes into remote.
Note that the instrument does not have to be in remote to be a talker.
Also, note that all front panel controls except for LOCAL and POWER are inoperative while
the instrument is in remote. You can restore normal front panel operation by pressing the
LOCAL key.
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 power supply 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.
Table 6-1
General bus commands
Command Effect on power supply
REN
IFC
LLO
GTL
DCL
SDC
GET
SPE, SPD Goes into remote when next addressed to listen.
Reset interface; all devices go into talker and listener idle states.
Local key locked out.
Cancel remote; restore front panel operation for the power supply.
Return all devices to known conditions.
Returns power supply to known conditions.
Initiates a trigger.
Serial polls the power supply.