NELLCOR PURITAN BENNETT LP6 Plus, Техническое руководство

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System Control System Control System Control System Control
LP6 Plus, LP10, and LP20 Technical Manual
November 2000
Page 4-10 Page 4-10 Page 4-10 Page 4-10
System Control System Control System Control System Control
All functions of the ventilator are controlled by a microprocessor. A
single Z80A microprocessor, running at 4 MHz, controls the motor,
alarm circuitry, battery charging system, meter drive, and solenoid
valve, along with interfacing with the printer.
The microprocessor reads the switches 10 times a second and con-
trols ventilator operation in accordance with what it finds.
The
VOLUME
VOLUME VOLUME
VOLUME
and
BREATHING EFFORT
BREATHING EFFORT BREATHING EFFORT
BREATHING EFFORT
controls are potentiometers. Their
value is an analog value, a voltage produced on the pot, which is
converted to a digital value by U19 on the logic board. All the
remaining controls,
INSPIRATORY TIME, BREATH RATE, LOW ALARM, HIGH ALARM/
INSPIRATORY TIME, BREATH RATE, LOW ALARM, HIGH ALARM/ INSPIRATORY TIME, BREATH RATE, LOW ALARM, HIGH ALARM/
INSPIRATORY TIME, BREATH RATE, LOW ALARM, HIGH ALARM/
LIMIT
LIMIT LIMIT
LIMIT
and
MODE
MODE MODE
MODE
,
are switches which set digital codes and require no
conversion to be read by the microprocessor.
Microprocessor Microprocessor Microprocessor Microprocessor Note:
There are two types of logic and power/motor boards that have been
used with LP6+ and LP10: an older through-hole board and a newer
surface-mount board. These can be distinguished by checking the
types of components on the circuit boards, plus the absence of a
power/motor board heat sink and fan assembly on surface-mount
units.
Refer to the Logic Board schematic in the Schematics Chapter. The
microprocessor, U28, is the heart of the system. The program is con-
tained in two memory ICS. An EEPROM (U24 used on older
through-hole board or U26 on the newer surface-mount board)
stores the calibration data and becomes accessible through the use
of the external calibrator. Two EPROMs (U25 and U26 used on older
through-hole board or U24 and U25 on the newer surface-mount
board) contain the program. The general structure of the program is
that every 10 ms (100 Hz) certain high priority tasks (i.e., pressure
read, printer output) are performed, then one of ten sub-programs
is performed (i.e., read and compute switch setting). Thus, each
sub-program is performed ten times per second. When the sub-pro-
gram is complete, the microprocessor waits for another 100 Hz
interrupt. In addition, the program is interrupted at 2400 Hz to per-
form certain high speed motor control functions.
The microprocessor sends an analog level to the motor controller,
causing the motor to rotate at a speed proportional to the level.
When a new volume/inspiratory time combination is set on the con-
trols, an initial speed control level is computed and sent to the
motor controller. After each stroke the actual inspiratory time is
computed and compared to the set value. The speed control level is