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Operation
Model 8902A
Remote/Loca I
Mode Descriptions
Remote Mode
In remote, the Measuring Receiver's front-panel controls are disabled except for
the LOCAL and CLEAR keys. The LOCAL and CLEAR keys are only disabled by Local Lockout.
However, front-panel displays and the output signal at MODULATION OUTPUT/AUDIO INPUT
remain active and valid. Two triggering modes are available in remote operation: Free Run and
Trigger Hold.
Displays which time out in Local
do
not time out in Remote. In Remote operation, the CLEAR key
will clear the display and works as a trigger when Trigger Hold is used.
Local Mode
In local, the Measuring Receiver's front-panel controls are fully operational. When
the Measuring Receiver goes to local operation, the front-panel REMOTE annunciator turns o f f ,
However, when the Measuring Receiver is being addressed (whether in remote o r local), its front-
panel LISTEN o r TALK annunciator lights. Free Run is the only triggering mode available in local
operation.
Mode Transitions
Local to Remote Transitions
The Measuring Receiver switches to remote operation upon receipt
of the Remote message. No instrument settings are changed by the transition from local to remote.
The Trigger mode will always be Free Run (TO) on entry to remote operation.
Remote to Local Transitions
The Measuring Receiver always switches to local from remote
whenever it receives the Local or the Clear Lockout/Set Local message. No instrument settings
are changed by the transition from remote to local, except the Trigger mode will always be reset
to
Free Run.
If it is not in Local Lockout mode, the Measuring Receiver switches to local from remote whenever
its front-panel LOCAL key is pressed.
NOTE
Remote to Local transitions will not slrtrr
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Local Lockout
Local lockout disables the LOCAL key (and the CLEAR key) and allows return-to-local o n l y under
program control.
When a data transmission is interrupted, which can happen if the LOCAL key is pressed, the data
being transmitted may be lost. This would leave the Measuring Receiver in an unknown state. To
prevent this, a local lockout is recommended.
3-26
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