Chapter 3
3-16
BiPAP Vision Service Manual © Respironics, Inc.
1062788
Theory of Operation
3.4.10
Vent Inop LED Current Check
An internal test verifies that the
Vent Inop
LED current is acceptable.
3.4.11
Error Line Control (ELC) Circuits
Redundant error signaling circuitry communicates error conditions among the
subsystems to minimize the chance of communication failures.
3.4.12
Error LED
The error LED lights to indicate that an error condition has been detected.
3.4.13
Diagnostic Interface
The diagnostic connector (J5) interfaces with the microprocessor so the DCS
board can download its diagnostic data to a service laptop computer for units
built s/n 105999 and below. For units built s/n 106000 and above, J5 sends
TDS/RDS data to J6 of the MC board, which processes the information then
sends it to the RS-232 connector on the back of the unit.
3.4.14
EEPROM
A serial EEPROM stores the set points for the backlighting and contrast, and
for the appropriate diagnostic data.
3.4.15
LCD Controller
The LCD controller interfaces with the display.
3.4.16
Debouncing/Keypad Matrix
The matrix keys are debounced and the microprocessor scans the matrix to
determine what key was pressed.
3.4.17
Rotary Encoder Control
The rotary encoder control circuit detects the following within one detent of
movement: relative position, direction, and speed of the rotary encoder.
3.4.18
Audible Alarm Activation
The audible alarm is activated by either an input from the ELC, the power fail
circuitry, or the test alarm signal from the MC board. An audible alarm also
occurs when an incorrect key is pressed, an adjustable parameter has reached
its limit, or the error signal has been activated.