IEEE-488 Reference
3-5
3.6
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 includ-
ed 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 com-
mands requiring that a primary address be specified assume
that the address is set to 27. This is the address that is set at
the factory.
3.6.1 REN (remote enable)
The remote enable command is sent to the Model 6517A 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 27"
' Place 6517A in
remote; turn on
REM annunciator
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
Effect on Model 6517
REN
IFC
LLO
GTL
DCL
SDC
GET
SPE, SPD
REMOTE 27
ABORT
LOCAL LOCKOUT
LOCAL 27
LOCAL
CLEAR
CLEAR 27
TRIGGER 27
SPOLL 27
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 6517A.
Cancel remote, restore front panel operation for all devices.
Returns all devices to known conditions.
Returns Model 6517A to known conditions.
Initiates a trigger.
Serial Polls the Model 6517A.
3.6.2 IFC (interface clear)
The IFC command is sent by the controller to place the Mod-
el 6517A 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 in-
strument; 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 27; *idn?"
' Send query com-
mand
PRINT #1, "enter 27"
' Read data; turn
on TALK annuncia-
tor
SLEEP 3
' Wait 3 seconds
PRINT #1, "abort"
' Talker idle
state; turn off
TALK annunciator
