6141.22X Incubator 8000 IC/SC/NC
Function Description
09.99 Page 39 of 49
g. Skin temperature sensor alarm
The output voltage (proportional to temperature) of the first amplifier stage is compared for
values that are outside the allowed range of temperature values. This could be caused by a
short circuit in the probe or a broken sensor cable.
h. Skin temperature sensor detection
Software version 10.n and 20.n: The plug of the skin temperature probe is coded in order to
indicate that the sensor is plugged in. A 5 V pull up resistor is connected to ground by a
jumper in the plug whenever the sensor is plugged in. This voltage is sensed by the
microprocessor via a port.
i. Oxygen sensor A, Inc. 8000 IC only
The output voltage of the oxygen sensor cell A is adapted to the ADC by the input amplifier
stage (33A). The output voltage of 0.0 mV to 120 mV is amplified to 0.0 V to 4.76 V.
j. Oxygen sensor B, Inc. 8000 IC only
The output voltage of the oxygen sensor cell B is adapted to the ADC by the input amplifier
stage (33B). Its amplification factor is reduced by the factor of 2.75 compared to the oxygen
sensor A. This different amplification factor is later compensated for by software. After analog
to digital conversion comparing signal B to the signal of oxygen cell A has to show the
discrepancy in values to be within a certain window. Errors because of false addressing of the
multiplexer are clearly detected. Resolution: 0.0 mV to 120 mV input voltage = 0.0 V to
1.73 V output voltage
k. O2 comparators, Inc. 8000 IC only
In addition to the microprocessor controlled check of the oxygen cell each cell is monitored
with an individual comparator. These comparators are set to a trigger level of approx. 7 mV. If
the output voltage falls below this limit, the relay (18)and the oxygen valve (3) are switched off
and the oxygen sensor alarm is activated.
l. Detection of sensor head position, Inc. 8000 IC only
The position of the sensor housing at the hinge is sensed by two micro switches installed in
the sensor housing and is evaluated via a PIA on the Motherboard PCB.
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