Datascope Passport 2, Руководство по обслуживанию

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SpO
2
UART Serial Interface Theory of Operation
2 - 56 0070-10-0441 Passport 2®/Passport 2 LT™ Service Manual
2.18 SpO
2
UART Serial Interface
The SpO
2
interface board provides SCI UART host communication to the SpO
2
modules. It
serves simply as an adapter. The signals, (TX, RX, SpO
2
RST_PB5, CTS, ETRIG), pass through
unchanged.
The SpO
2
interface board will be specifically configured for the SpO
2
module it is
interfacing with. This may include different jumper settings, different feedback resistor
options, custom ribbon cables, different SpO
2
ID resistors, etc.
The J4 (Nellcor MP506), J5 (Nellcor MP304), and J6 (Masimo MS-3) connectors are used for
these interfaces. To help the software decide which SpO
2
module is under use, three SpO
2
identification bits are available for reading on general purpose inputs by the Passport front
end microprocessor.
An ESD protection device, U1, is connected to the SpO
2
communications signals. C1 to C4
are decoupling capacitors connected to the ground and shield. CR1 is a do not populate,
and is used as a contingency protection circuit for the U3 regulator. CR1's purpose is to
allow current to flow backwards from the output to the input of the linear regulator during
power-down to remove residual charge on the output capacitors.
2.18.1 Panel Interface Extension Connector
In order to physically and mechanically connect the Nellcor MP506 board to this SpO
2
Interface board, a pass through or extension connection for the panel interface signals had
to be placed on the SpO
2
Interface board. Therefore three connectors are used when
interfacing to a Nellcor MP506. One connector J4 is for the SpO
2
signals. The second and
third connectors, J1 and J2, are the extension for the panel interface signals.