Siemens SC 7000 Service Manual page 46

Service Manual
11.1 System Hardware
11.2 System Memory
11.3 User Interface
12HEMO 2/4 POD
12.1 Functional Description
12.2 Pressure
30
The module is a three-part system composed of a Digital Board, an Analog
Board, and an Accessory Assembly. The Digital Board has two major
functional areas: the power supply section and the bulk of the digital control
logic. The Analog Board provides for data acquisition and conversion, and
contains the servos for controlling the temperature of the case and detector
heaters, and the source pulser used to control the probe. The Accessory
Assembly contains the CO
calibration switches and calibrator EEPROM).
The system has three types of memory:
• PROM Programmable Read Only Memory
• SRAM Static Random Access Memory
• EEPROM Electrically Erasable Read Only Memory
PROM stores the module's program. Its contents remain intact even when
power is removed from the module. It has been socketed to allow for future
program updates, if required. Besides containing the module's program, it
also contains various look-up tables for calculating CO
the Interrupt Vector Table.
The system's Static RAM functions as a scratch pad to temporarily hold
various system variables until they are either no longer needed by the
system and are overwritten with new information, or power is removed from
the module and the RAM contents are lost.
The EEPROM holds system parameter information that must be retained
when power is removed, but must also be modifiable by the processor. The
device contains multiple copies of system information such as calibration
factors, sensor serial number, and span cell number, to ensure data
integrity.
A Supervisor chip performs various monitoring tasks to ensure that the
microprocessor and system run properly.
The user interface provides capability for airway and adapter calibration,
and also compensation for effects of N
accessory assembly, switches inside the sensor, one for the Zero Cell and
one for the Span Cell, tell the processor when the assembly has been
placed on the proper cell for system calibration.
HEMO 2/4 PODs have provisions for monitoring either 2 or 4 invasive blood
pressures, 2 temperatures and cardiac output. See
The pressure data acquisition front end is designed to operate with resistive
strain gage pressure transducers having an output impedance of less than
3000 Ohms and an input impedance between 3000 and 200 Ohms (see
Figure 2-17). Excitation voltage is applied, one at a time, to each resistive
strain gauge pressure transducers by a single, current limited voltage
reference circuit which is time-multiplexed across four pressure sensors.
The differential output signals generated by the pressure sensors are
passed through filter and clamp networks which limit the differential and
common mode voltage swings and filter out RF noise.
Siemens Medical Systems, EM-PCS, Danvers
NOT A CONTROLLED DOCUMENT
SC 7000 and SC 9000XL Patient Monitors
sensor and the Calibrator (that contains the
2
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2 2
Figure 2-16
7k9kXLTM.c2.CD_ROM.fm/04-99/kaupp
parameters and
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