General Bus Commands; Table 3-1 General Bus Commands And Associated Statements; Ren (Remote Enable); Ifc (Interface Clear) - Keithley 2002 User Manual

IEEE-488 Reference
3.5

General bus commands

General bus commands are those commands such as DCL
that have the same general meaning regardless of the instru-
ment. Table 3-1 lists the general bus commands. Also
included is the programming statement for each command
using the Keithley KPC-488.2 IEEE interface and the HP-
style Universal Language Driver (CECHP). Note that the
commands requiring that a primary address be specified
assume that the address is set to 16. This is the address that
is set at the factory.

3.5.1 REN (remote enable)

The remote enable command is sent to the Model 2002 by
the controller to set up the instrument 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. Instead the instrument must be addressed to lis-
ten after setting REN true before it goes into remote.
Note that the instrument need not be in remote to be a talker.
Program fragment
PRINT #1, "remote 16"
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.

Table 3-1

General bus commands and associated statements

Command Programming statement
REN REMOTE 16
IFC ABORT
LLO LOCAL LOCKOUT
GTL LOCAL 16
LOCAL
DCL CLEAR
SDC CLEAR 16
GET TRIGGER 16
SPE, SPD SPOLL 16
3-4
' Place 2002 in remote;
turn on REM annunciator
Effect on Model 2002
Goes into effect when next addressed to listen.
Goes into talker and listener idle states.
LOCAL key locked out.
Cancel remote, restore front panel operation for 2002.
Cancel remote, restore front panel operation for all devices.
Returns all devices to known conditions.
Returns Model 2002 to known conditions.
Initiates a trigger.
Serial Polls the Model 2002.

3.5.2 IFC (interface clear)

The IFC command is sent by the controller to place the
Model 2002 in the local, talker, and listener idle states. The
unit responds to the IFC command by cancelling front panel
TALK or LISTEN 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 need only set the
IFC line true for a minimum of 100µsec.
Program fragment
PRINT #1, "output 16; *idn?" ' Send query command
PRINT #1, "enter 16"
SLEEP 3
PRINT #1, "abort"

3.5.3 LLO (local lockout)

The LLO command is used to prevent local operation of the
instrument. After the unit receives LLO, all its front panel
controls except POWER are inoperative. In this state, press-
ing LOCAL will not restore control to the front panel. The
GTL command restores control to the front panel.
Program fragment
PRINT #1, "remote 16"
RINT #1, "local lockout" ' Lock out front panel
SLEEP 6
PRINT #1, "local 16"
' Read data; turn on
TALK annunciator
' Wait 3 seconds
' Talker idle state;
turn off TALK annun-
ciator
' Place 2002 in remote
(including LOCAL key)
' Wait 6 seconds
' Restore front panel op-
eration