baxter Flo-Gard 6301, Service Manual, Page: 192 / 252

12
CPU System
12-4
FLO-GARD 6301 DUAL CHANNEL VOLUMETRIC INFUSION PUMP SERVICE MANUAL 07-19-B1-729
The UPP generates 2 kHz and 4 kHz signals for the audible alarm and key
beep and a 17 kHz signal for the door open sensor, and the signal for
backlight dimming.
The UPP also interrupts the master CPU each time a pulse is received from
the motor rotation detectors, when an interrupt signal from slave CPU is
received or when the pump communicates with an external PC.
The UPP is used to select the baud rate for external communications. The
baud rate is set at power-up according to the configuration setting.
Communication Controller
See Figure 13-11 and Figure 13-14. The communication controller allows the
pump to communicate with an external computer through an RS-232C
interface. The baud rate is selectable and controlled by the universal pulse
processor.
Air Sensor Circuit
See Figure 13-11, Figure 13-22, Figure 13-24, Figure 13-36, and
Figure 13-37. The air sensor circuits for both pumps are identical. Each
circuit consists of an ultrasonic transmitter and receiver mounted on opposite
sides of the tubing path. The transmitter consists of a 500 kHz oscillator and a
selector that transfers the oscillator output to two of three transducers. The
transducers are selected by the air bubble alarm size setting in the
configuration option. The receiver contains a selector that transfers the
transducer outputs to the UPP through an amplifier.
The transducers operate on the principle that air in the tubing transmits
ultrasonic energy much less effectively than fluid. This energy is amplified,
rectified, applied to the UPP and then converted into a digital signal. The
master CPU monitors the signal and activates an AIR alarm when it detects
the absence of a precise level of energy.
Occlusion Sensors
Downstream Occlusion Sensor
See Figure 13-10, Figure 13-23, Figure 13-36, and Figure 13-37. The
downstream occlusion sensor consists of a moving ferrite core inside a
mechanically fixed oscillator coil. The moving ferrite core is spring loaded
against the administration set. When pressure downstream of the pump
increases, the core moves from its original position, which in turn changes the
frequency of the oscillator.