4.4 PGM/PGM2 electronics
4.4.1 MOPS PCB (PGM/PGM2)
“MOPS” stands for “Modular Platform for Sensors”. It is a modular concept by which suitable sensor components (pneumatic and mechanical components) can be operated together by way of a processor board.
The resultant arrangements are supported by a software program with a form communications interface. In this way, the user is provided with a uni-form view of the parameters on offer, irrespective of the components deployed.
The software is automatically configured for the connected components when the system starts up.
With this concept, different gas sampling modules (for example “ILCA2” and
“IRIA”) can be configured for specific customer needs using standard compo-nents.
The MOPS PCB calculates the values of the patient parameters and controls the sensor head signals.
4.4.2 AMO IRIA PCB (PGM) “AMO” stands for “Adapter MOPS”. The PCB has the following tasks:
– Convert digital target values from the MOPS PCB into analog voltages for the IRIA emitter.
– Generate the IRIA supply voltage.
– Data transfer from the IRIA sensor to the MOPS PCB (data evaluation).
4.4.3 AMO ILCA2 PCB (PGM2) “AMO” stands for “Adapter MOPS”. The PCB has the following tasks:
– Convert digital target values from the MOPS PCB into analog voltages for the ILCA2 emitter.
– Generate the ILCA2 supply voltage.
– Data transfer from the ILCA2 sensor to the MOPS PCB (data evaluation).
4.4.4 AMO O2 PUMP PCB (PGM)
The PCB has the following task:
– Transfer the O2 sensor data to the MOPS PCB (data evaluation).
4.4.5 AMO MFM PCB (PGM2) The PCB has the following task:
– Transfer the O2 sensor data (Servomex) to the MOPS PCB (data evalua-tion).
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4.4.6 AMO FLOW ILCA PCB (PGM/PGM2)
The AMO FLOW ILCA PCB controls the pump and the valves of the PGM/PGM2. The PCB is controlled and powered by the MOPS PCB. The actual regulation of the pump flow is handled by the software of the controller on the MOPS PCB.
The AMO FLOW ILCA PCB holds the following components:
– A DC/DC converter generates the pump voltage (2.5 - 7.5 V/DC). The output voltage of the DC/DC converter is controlled with a digital potenti-ometer on the PCB. The digital potentipotenti-ometer is regulated by the MOPS PCB.
– The output stage to operate the valve.
– Service LEDs for the pump voltage, the valves and the supply voltage – The temperature-compensated differential pressure sensor for flow
mea-surement. The sensor offset is corrected with a digital potentiometer.
– The analog electronics for evaluation of the pump voltage, pump current, valve current and differential pressure.
The flow is measured by way of the differential pressure of restrictor R1 plus the upstream (sintered-metal) filter. The measuring range is 0 mbar to 350 mbar.
The AMO FLOW ILCA PCB is connected directly to a 60-pin connector on the MOPS PCB and is detected automatically by the MOPS PCB.
The function description relating to the mixer follows.
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5 Mixer
This section describes the mixer for the AIR, N2O and O2 gases. The newly generated fresh gas is fed through the vaporizer to the VGC.Figure 25 Mixer position, with rear panel open
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Figure 26 Mixer without hood, for legend see Table 11
Table 11 Legend to Figure 26
Item Components
1 PRIMUS CPU PCB
2 Gas inlet block 3 Mixer block 4 A-cone valve 5 Fresh gas tank
6 MIXER PCB
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Figure 27 Block diagram of fresh gas metering, legend Table 12
Table 12 Legend to Figure 27
The item numbers and abbreviations occurring in this section relate to Figure 27 .
On the MCP (1) the user selects the carrier gas AIR or N2O as well as the fresh gas flow and the O2 concentration.
A CAN bus (2) transfers the setup parameters to the mixer electronics (3).
The mixer electronics generate the actuation signals for the gas inlet
Item Component
1 Monitor Control Panel (MCP)
2 CAN bus
3 Mixer electronics (PRIMUS CPU PCB/MIXER PCB) 4 Fresh gas outlet
5 Fresh gas flow valve 6 Fresh gas tank 7 Gas inlet valves 8 Pressure regulator
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The fresh gas flow valve (5) delivers the selected fresh gas flow. The flowme-ter at the fresh gas outlet (4) regulates the fresh gas flow valve.
5.1 Operating modes
The operating mode is regardless of whether the Primus is powered from the mains via its power plug or is powered up in battery mode.5.1.1 10 VA mode Internal leakage may mean that the O2 concentration in the Primus is above 21% when operation is begun. “10 VA” mode prevents dangerous operating states from occurring.
When the power plug is connected to the mains power but the power switch is not yet switched on, the following safety rule applies:
– A supply voltage of only 10 VA is fed into the interior of the mixer (10 VA is the product of the no-load voltage and short-circuit current of the supply voltage “24 V PLUG-IN”. Only the DC/DC converters (-15 V, +15 V) for the pressure sensor amplifiers are supplied).
– The pressure sensors for the gases from the central supply (CS) system and the cylinder supply are read and the compressed gas supply status is indicated by LEDs on the front panel (see 5.3.2 Pressure status LEDs).
When the Primus is switched on at the power switch (mains or battery pow-ered) the following safety rule applies:
– Before other modules receive operating voltage, the fan in the mixer is switched on for at least 10 seconds. Only then is “Normal” mode acti-vated.
5.1.2 'Normal' mode In this mode the mixer CPU PCB controls normal mixing. All DC/DC convert-ers (+5 V, +24 V, -15 V, +15 V) are supplied with “24 V SWITCH”.