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

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Datex-Ohmeda S/5 monitors
Document No. 800 1008-2
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RS485 communication
The communication to the CPU board of the monitor uses RS485 protocol. The RS485 driver
circuits are optically isolated from the processor of the module. PWM signal is used for direct ECG
signal. Direct ECG signal is available from the X2 connector of the UPI board or from the PT module.
Power supply
The ECG board has a driver controlled half bridge switching power supply with 5 kV isolation. The
supply voltages have been regulated with linear regulators.
2.2.6 ECG filtering
The S/5 monitors have three ECG filtering modes:
MONITORING
0.5...30 Hz (with 50 Hz reject filter)
0.5...40 Hz (with 60 Hz reject filter)
DIAGNOSTIC @ 12-lead ECG 0.05...150 Hz
DIAGNOSTIC @ other modules 0.05...100 Hz
ST FILTER
0.05...30 Hz (with 50 Hz reject filter)
0.05...40 Hz (with 60 Hz reject filter)
The purpose of filtering is to reduce high frequency noise and low frequency (e.g. respiratory)
movement artifacts.
Monitor filter is used in normal monitoring. Diagnostic filter is used if more accurate diagnostic
information is needed. ST filter gives more accurate information of ST segment, but reduces high
frequency noise.
The high-pass filters 0.5 Hz and 0.05 Hz are done with hardware. The monitor sends a command to
the hemodynamic module determining which of the corner frequencies 0.5 Hz or 0.05 Hz is to be
used.
The 50 Hz and 60 Hz reject filters are both low-pass filters with zero at 50 Hz or 60 Hz
correspondingly and they are done with software. They are for the mains supply filtering. When
these filters are used, 3 dB value for low-pass filter is 30 Hz or 40 Hz.
In diagnostic mode the upper frequency is limited by hardware and the -3 dB frequency is 100 Hz
for 3 or 5 lead ECG measurement. For 12 lead ECG the upper frequency is 150 Hz and it is limited
by software.