IEEE-488 PROGRAMMING
3.8 GENERAL BUS COMMAND
PROGRAMMING
Generd bus commands are those commands such as DCL
that have the same general purpose regardless of the in-
strument. Con%naxids supported by the Model 199 are
summarized in I3ble 3-6, which lists BASIC 4.0 statements
necessary to send each command. Note that commands
requiring a primary address assume that the Model 199
primary address is set to 26 (its factory default~address).
3.8.1 REN (Remote Enable)
REN is a uniline command that must be asserted by the
controller to place the Model 199 in remote. Simply set-
ting EN true will not adually place the instrument in
remote; instead, the unit must be addressed to listen after
REN is set true.
Generally, remote enable should be asserted before at-
tempting to program the instrument over the bus. Once
the instrument is in remote, all front panel controls except
LOCAL~will be inoperative. Normal front panel operation
can be restored by pressing the LOCAL key.
To place the Model 199 in remote, the controller must per-
form the following sequence:
1. Set the REN line true.
2. Address the Model 199 to listen.
Pmgxamming Example-Place the Model 199 in remote
with the following statement:
PEMOTE 7215
The Model 199 should be in remote, as indicated by the
annunciator light. If not, check to see that proper bus con-
nections are made, and that the instrument is programm-
ed for the correct primary address (26).
Note that all front panel controls except LQCAL (and, of
course, POWER) are inoperative while the inshument is
in remote. You can restore normal front panel operation
by pressing the LOCAL button.
3.8.2 IFC (Interface Clear)
The FC command is sent by the controller to place the
Model 199 in the talker and listener idle states. The~unit
will respond to the IFC command by cancelling TALK or
LISTEN, if the instrument was previously placed in one
of those modes.
To send the IFC command, the controller need only set
the IFC line true for a minimum of 1OO~sec.
Table 3-6. General Bus Commands and Associated BASIC Statements
BASIC 4.0~
Statement
Affect on Model 199
REMOTE 7 Goes into remote when next addressed.
IZIEORT 7 Goes into talker and listener idle states.
LOCAL LljC:Kijl-lT ;
Front LOCAL key locked out.
LljCkL 726
Cancel remote.
C’LEAR 7
Returns to default conditions.
CLEAR 726
Returns to default conditions.
TF: I GGER 725. Triggers reading in TZ and T3 modes.
3-10
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