Datex-Ohmeda S/5 M-NE12STPR, Technical Reference Manual Slot

Page: 28 / 88

Datex-Ohmeda S/5 monitors
Document No. 800 1008-2
22
Red and infrared channel separation
Red and infrared channels are separated from each other by switches. Operational amplifier
functions as a buffer and after this infrared DC signal is sent to the processor. A capacitor
separates AC signal from it and the AC signal is sent to the processor after amplification. There is a
switch to choose the amplification constant.
Serial communication
Serial communication between the module and the frame is done by RS485 type bus whose
buffers get their supply voltage (+5 VDC) from the Frame and in the isolation section get the supply
voltage (+5 V) from the isolated power supply.
The buffers of the serial communication are controlled also by Reset signal so that when the Reset
is active, the buffer does not transfer data.
Reset is also RS485 type and additionally, there is an auxiliary logic power reset, which keeps the
reset active for about 500 ms despite the state of reset in the module bus. Time constant
determines the power-up reset time. There are components to prevent the module from sending
data during reset. Data transmission rate is 500 kbps.
RS485
Driver
RS485
Driver
Reset
Send data
Receive data
send/receive
Receive data
Send data
send/receive
Reset
m
o
du
le
p
r
o
s
e
sso
r
Opto isolation
Pa
ti
en
t
Is
o
la
ti
o
n
Receive data
Send data
send/receive
Reset
m
odul
e
p
r
o
se
ss
o
r
Opto isolation
Pa
ti
en
t
Is
o
la
tio
n
STP Board
ECG Board
RS485
Driver
RS485
Driver
Reset
Send data
Receive data
Receive data
Send data
send/receive
Reset
m
o
dul
e p
r
o
s
e
s
s
or
NIBP Board
Data
NData
Reset in
NReset in
m
odul
e bus connect
or
connect
or f
o
r STP board
connect
or f
o
r NI
BP board
Data
NData
Reset in
NReset in
send/receive
connect
or f
o
r STP board
Receive data
Send data
send/receive
Reset
connect
or f
o
r ECG board
Figure 12 Serial communication and opto isolation of M-NESTPR/-NE12STPR