
4 Using the System Utilities
94 Model N6705A User’s Guide
As shown above, you can also connect the Inhibit input to a manual
switch or external control signal that will short the Inhibit pin to
common whenever it is necessary to disable all output channels in
the mainframe. Negative polarity must be programmed for all pins in
this case. You can also use the Fault output to drive an external relay
circuit or signal other devices whenever a user-definable fault occurs.
Clearing a System Protection Fault
To restore all instruments to a normal operating condition when a
fault condition occurs in a daisy-chained system protection
configuration, two fault conditions must be removed:
1. The initial protection fault or external Inhibit signal.
2. The subsequent daisy-chained fault signal (sourced by the
Inhibit signal), as previously explained under "Inhibit Input".
NOTE
Even when the initial fault condition or external signal is removed, the Inhibit
fault signal is still active and will continue to shut down all mainframe outputs.
To clear the daisy-chained fault signal if the operating mode of the
Inhibit input is Live, simply clear the output protection on any
ONE
mainframe as explained in chapter 3. If the operating mode of the
Inhibit input is Latched, turn off the Inhibit input on
ALL mainframes
individually. To re-enable the chain, re-program the Inhibit input on
each mainframe to Latched mode.
Trigger In
Any of the Digital Control pins can be programmed to function as a
trigger input. All pins are referenced to the Signal Common pin.
To input an external trigger signal, you can apply either a negative-
going or a positive-going pulse to the designated trigger input pin.
The trigger latency is 5 microseconds. The minimum pulse width is 2
microseconds. The pin’s polarity setting determines which edge
generates a trigger-in event. Positive means a rising edge and
Negative means a falling edge.
You can configure the Scope and the Data Logger to be triggered by
external trigger signals. Simply select BNC Trigger In as the trigger
source when configuring the Scope or Data Logger properties. This
will enable input trigger signals on both the configured digital pin as
well as on the BNC trigger input connector.
FLT
INH
1 2 3 4 5 6 7
I
1 2 3 4 5 6 7
I
1 2 3 4 5 6 7
I
FLT
INH
FLT
INH
+ - + -
+ -
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