Siemens Servo i, Service Manual, Page: 24 / 70

Siemens-Elema AB
Description of functions Servo …
E382 E407E 061 01 01 02
3 - 8
3
PC 1784 Expiratory Channel
Functional Main Blocks diagram marking: “
F
”
The main block E
XPIRATORY CHANNEL
comprises
microprocessor control to achieve measurement of
expiratory flow. The output signal E
XP
. F
LOW
is used in
the main block C
ONTROL
.
Electronics including microprocessor (
m
P) for handling
of:
• All electronic connections to and from the
E
XPIRATORY
S
ECTION
functions.
• Measurement of airway pressures in both
I
NSPIRATORY
S
ECTION
and E
XPIRATORY
S
ECTION
.
• Control of the S
AFETY
V
ALVE
functions in the
I
NSPIRATORY
S
ECTION
.
Includes also an ID PROM. The ID information can be
read by the Servo
… System.
PC 1771 Control
Functional Main Blocks diagram marking: “ C ”
The main block C
ONTROL
comprises microprocessor
control of Breathing pattern for all different ventilation
modes.
Electronics including microprocessor ( m P) control to
achieve:
1. Regulation of Inspiratory flow which is used
during inspiration time in Volume Control (VC)
mode.
2. Regulation of Inspiratory pressure which can be
used during inspiration time in any mode.
3. Regulation of a constant Inspiratory flow which is
used during expiration time in all modes.
4. Respiratory timing pattern including frequency as
well as distribution of the duration for Inspiration
time, Pause time and Expiration time according to
front panel settings.
5. Regulation of Inspiratory flow during inspiration
time. The desired total Inspiratory flow value
according to front panel settings is used to gene-
rate the flow reference signals I
NSP
F
LOW
R
EF
1
and I
NSP
F
LOW
R
EF
2. The level relation between
these two flow reference signals depends on the
desired O
2
concentration according to front panel
setting. I
NSP
F
LOW
R
EF
1 and I
NSP
F
LOW
R
EF
2 are
used for the control of its respective G
AS
M
ODULE
(Air and O
2
).
Regulation of a constant Inspiratory flow during
expiration time: The desired constant Inspiratory flow
value is the default or preset Bias flow value (see
User’s manual).
This desired constant Inspiratory flow value is used to
generate the flow reference signals I
NSP
F
LOW
R
EF
1
and I
NSP
F
LOW
R
EF
2 with the same relation and same
handling as described above under ”Regulation of
Inspiratory flow…” except this occurs during
expiration time.
Includes also an ID PROM. The ID information can be
read by the Servo
… System.
PC 1772 Monitoring
Functional Main Blocks diagram marking: “ M ”
The main block M
ONITORING
comprises microprocessor
calculation of parameters and monitoring of alarm
limits with control of alarms (as well as back-up
alarm). The main block M
ONITORING
cooperates with
the L
OUDSPEAKER
in the User Interface.
The PC 1772 M
ONITORING
handles all supervision and
alarms in the system. It activates pressure reducing
mechanisms, including activation of the safety valve,
in case of excessive breathing system pressure.
All alarms are conveyed and displayed on the front
panel and the alarm sound is also generated. In case
of malfunction in the loudspeaker, located in the User
Interface, a back-up sound generating device on
PC 1772 will be activated automatically.
The following voltages are supervised :
• +24 V
• +12 V
• -12 V
• +5 V
• +3.3 V.
A buzzer on PC 1772 M
ONITORING
generates the alarm
signal in case of +5 V or +3.3 V power failure. The
buzzer and +5 V / +3.3 V failure logic is powered by
back-up capacitors in case of power failure.
PC 1772 also contains a barometric transducer and
the measured barometric pressure is supplied to the
other units in the system.
Trending of measured parameters are performed by
M
ONITORING
.