Nellcor N-180, Руководство пользователя

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Section 3: Functional Block and Circuit Analysis
3-13
0V
7
6
8
10
11
9
15
14
16
2
U24A
3
1
0V
20
19
24
13
15
U20
Dual
Channel
A:D
Serial
Output
U24B
U24C
U24D
ADCDATA
ADCCHN
VCAL1
RED_ADC
IR_ADC
VCAL 2
RESISTORS
REF2.5
1
U7A
2
6
U19
2.5V Ref
Figure 3-5: Oximetry Module Analog to Digital Conversion Circuits
Support Circuits
Support circuits include the following:
• Communications
• Processor circuits
• Power
■
Communications:
The oximetry module CPU (figure 3-6) manages communications to
other monitor electronics. There are two data signals (RXD, TXD) and
three control signals at the module connection to the CPU PCB.
CTS* clear to send is a logic signal (active low) transmitted to the oximetry
module by the monitor to suspend data transmission from the module
RESET* is an input (active low) from the main processor to effect a reset in the
oximetry module
RXD is the receive data line from the CPU PCB
TXD is the transmitted data line to the CPU PCB
C-LOCK external synchronizing signal from
ECG
monitor (not used)
The communication data link is bi-directional-asynchronous and serial.
Transmissions are checked for errors; the presence of an error is
evidence of a hardware problem. No transmission retry capability is
included.