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IEEE-468 PROGRAMMING
4.8.2 IFC (Interface
Clear)
The IFC command is sent by the controller
to place the
Model 194 in the talker and listener idle states. The unit
will respond to the IFC command by cancelling front panel
TALK or LISTEN lights, 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 100~s~~.
HP-85 Programming
Example-Before
demonstrating
the
IFC command,
place the instrument
in the talker active
state with the following
statements:
At this point, the REMOTE and TALK indicators
should
be on.
Thr IFC command can be sent by typing in the following
statement:
Note that the TALK indicator
turns off when the END
LINE key is pressed.
Model 8573 l'rogramming
Example-Place
the instrument
in the remote and talker active states with the following
statements:
/,.I I:.;; 1 1, I::: ('i L,, /, 1: E: 5; i;; 1; (1 1: I:: L, 13 :.: ) I.,! ::.; ::,
,I: p, 1, f z:: c: t, ,::; $ I:: :/.: t, 4~ ,3 ;:I [: fi i i I B c:: p1 1, /: L: ,+ r, gj ::.; ? I::: p, [, :$ ::,
After the return key is pressed the second time, the in-
strument should be in the talker active state, as indicated
by the respective indicators.
To send IFC, enter the following
statement into the IBM
PC:
1:: 11 ii
I E i I $1: 8:: E: F: 1, @ % ::I
After the return key is pressed, the instrument
will return
to the talker idle state.
4.8.3 LLO (Local Lockout)
The LLO command is used to lock out operation
of the
LOCAL key, thereby completely
locking out front panel
operation of the instrument
(recall that the remaining con-
trols are locked out when the instrument
is placed in
remote). Operation
of the LOCAL key can be restored by
using the GTL command, as described in paragraph 4.8.4
below.
The instrument
must be in remote to respond to LLO.
However, if you send LLO with the unit in local and REN
true, it will go into local lockout when next placed in
remote. To permanently cancel LLO, REN must be set false.
To send the LLO command,
the controller
must perform
the following
steps:
1. Set ATN true.
2. Place the LLO command byte on the data bus.
HP-85 Programming
Example-To
verify LLO operation,
enter the following
statements:
l?Ei,i:,,-E: ';~w
L. i:, I: A i. I.. $3 c: ,::: ci IJ 1 '7
After the second statement is executed, the LOCAL key
will be locked out.
Model 8573 Programming
Example-Enter
the following
statements
into the IBM PC to demonstrate
the LLO
command:
4.8.4 GTL (Go To Local)
The GTL command is used to take the instrument
out of
the remote mode and restore operation of the front panel
keys.
4-12
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