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SIARETRON 1000 – 1100 - 3000
Service Manual
PANEL (PANEL MANAGER)
The panel control board, contains an Hitachi H8/325 micro controller which effects the keyboard reading and
displays management.
It communicates with the main micro controller (H8/532 on the LV200-MAIN/1 board) through a serial port; it
forwards the acquired buttons and receives the data to be displayed using an internal protocol.
The board is equipped with WATCH DOG circuit not sensible to electric power supply realized with an NE555;
such a circuit is able to generate a microprocessor reset if it is not periodically "refreshed" by the software,
retaking the machine in a know status in case of not correct performance of working program.
The program, which is located in an EPROM inside the micro controller, performs a complete scanning of
keyboard approx. each 260 µs and manages the displays with a multiplexer frequency of approx. 47 Hz.
LV200I/O (INPUT/OUTPUT)
Input/output board managing the pneumatic circuit.
The printed circuit is divided in two sections, whom are kept separate as most as possible, an analog and a
digital one.
In the analog part there are stabilizers for the necessary electric power supplies (+10 V, -10 V) and all circuits
for input signals conditioning, namely the amplifiers, filters, protection devices.
The analog inlets are:
pressure signal (from transducer MPX10 mounted on board edge);
•
O2 concentration signal (from an external oxymetry sensor);
•
MINUTE VOLUME setting signal (from potentiometer on the panel);
•
measurement signals of O
•
The mass of the analog section is physically kept separate from the mass of digital section; the only contact
point of these two masses is on the LV200-MAIN/1 board on the microprocessor pins.
The digital section of the board includes:
two digital inlets (contact cleaned by the two pressure switches);
•
an outlet for signaling buzzer
•
an ON/OFF electro valve outlet for medical gas commutation flow;
•
two outlets for flow by-pass;
•
two control outlets for proportional electro valves which regulate the flow of the two medical gas.
•
The proportional electro valves control is performed in PWM by two integrated circuits TL494, arranged on a
commutation frequency of approx. 30 KHz. The feedback of each of these integrated circuits is made on the
electric power of the relevant proportional electro valve; the set point (as electric power) is supplied by main
micro controller (H8/532 of LV200-MAIN/1 board) through an integrated low frequency signal PWM.
SIARETRON_SE3_en
and AIR flows (from two external flow meters).
2
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( rev.3) 30.06.2004
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