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区 JALLINCKRODT
KEYBOARD AND SENSOR INTERFACE
800961-C Nov. 2000
NOTE:
The keyboard contains eight normally open switches: fill, expel,
start/pause, three fast switches, Auto-Fill Mode and Auto-Fill Vol-
ume.
The three "fast" switches are electrically tied together. One
side of each switch is connected to an input port on the microcon-
troller. Each of these lines is pulled up by a resistor, RN-1 or RN-2.
The other side of the switches are tied to ground. Therefore, a high
voltage on the input port indicates the switch is open. A low volt-
age on the input port indicates the switch is closed.
Refer to schematic LF P/N 800573 at the end of this chapter. There
are two bipolar hall effect sensors mounted to the hall effect circuit
board and connected to the powerhead PCB via ribbon cable J13.
The sensors detect the polarity of the magnets in the face plate and
locking ring. The two signals, called "Face Plate A" and "Syringe
Present A", are driven low when a magnetic south is detected. The
two signals, called "Face Plate B" and "Syringe Present B", are
driven low when a magnetic north is detected.
All four of these
signals remain high when no magnet is present. Table 3-12 below
indicates the size and type of the syringe sensed by the powerhead
for all possible face plate magnate conditions.
There must be a magnet present (i.e., either north or south polarity)
at the Syringe Present sensor in order for the system to function.
Table 3-12. Syringe Size Sensing
Syringe Present A
Syringe Present B
No Face Plate Magnet
200 mL (Liebel-Flarsheim)
100 mL Hand-Held
Face Plate A
125 mL Prefilled
30/50 mL Prefilled
Face Plate B
Reserved
200 mL Hand-Held
3-41
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