The Keysight AC68BFIU Fault inhibits board allows you to control the output state with an external input signal in two modes:

• Latching mode
• Live mode

Please note only one slot is available for either the AC68BFIU Fault Inhibit Card, AC68BALGU Analog Card, or AC68BGPBU GPIB Card.

Latching mode

Latching mode disables the output when the inhibit signal is true. This is treated as a protection event, and output remains disabled regardless of subsequent inhibit signal changes. To return the output to normal operation, the Inhibit input must remain false and the latched inhibit signal must be cleared. The output remains off after the protection is cleared and must be re-enabled to turn it on again.

Live mode

Live mode allows the enabled output to follow the state of the inhibit signal. When the inhibit signal is true, the output is disabled; when the inhibit signal is false, the output is enabled. The inhibit signal is not latched, and the inhibit event is not treated as a protection event. Therefore, a protection clear is not required when switching between inhibit true and inhibit false.

As shown in the following figure, you can connect the Inhibit input to a manual switch or external control signal that will short the inhibit pin to ground whenever it is necessary to disable the output. Negative polarity must be programmed for the inhibit pin in this case.

In Live mode, when the switch is closed (Inhibit signal is true) the output is disabled. When the switch is opened (Inhibit signal is false), the output will once again follow the output state setting.

In latching mode, when the switch is closed (inhibit signal is true) the output is disabled. This is treated as a protection event, and output remains disabled regardless of subsequent inhibit signal changes. To return the output to normal operation, the switch must be opened and the latched inhibit signal must be cleared. The output remains off after the protection is cleared and must be re-enabled to turn it on again.