Nellcor OxiMax N-550, Service Manual

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Data Port Interface Protocol
N-550 91
5. Select baud rate by pressing Adjust Up or Adjust Down button (2400,
9600, or 19200 [default]).
6. Press the SatSeconds Alarm Limit button to set the selection.
Connecting To The Data Port
Data is transmitted in the RS-232 and RS-422 formats. RS-232 data can be
transmitted a maximum of 25 feet (7.62 meters). The RS-422 data can be
transmitted a maximum of 4,000 feet (1,219.2 meters). The pin outs for the
data port are listed in Table 13.
TXD+ and TXD- are the differential transmit data pair. RXD+ and RXD- are
the differential receive pair.
Table 13: Data Port Pinouts
Pin Signal Name
1 RXD+ (RS-422 positive input)
2 RXD (RS - 232 input)
3 TXD (RS - 232 output)
4 TXD+ (RS-422 positive output) (-5 to -12 VDC with no audible
alarm, 5 to 12 VDC with audible alarm)
5 Signal Ground (isolated from Earth Ground)
6 NC (No connection)
7 Normally Open (N.O. with no audible alarm), dry contact for Nurse
Call
8 Normally Closed (N.C. with no audible alarm), dry contact for
Nurse Call)
9 RXD- (RS-422 negative output)