Chapter 3
Theory of Operation
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BiPAP Vision Service Manual © Respironics, Inc.
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3.4.19
Audible Alarm Current Check
An internal test verifies that the audible alarm current is acceptable.
3.4.20
Safe State Power On
The DC board contains circuitry that power on the hardware in a safe state. In
a safe state, the backlight is off, the display is off, and the ICB is terminated.
When the MC board determines that no Vent Inop error exists, it allows the
device to resume operation under normal operating conditions.
3.4.21
Watchdog and Low Voltage Reset
The watchdog function must be periodically reset by the microprocessor if a
time-out period has been exceeded. This function resets the processor if the
software stops functioning correctly. When a low logic level is detected, the
ELC is activated and the system shuts down.
