5. Electronics
Pump(s), UF- Concentrate Proportioning, and Input/Output
systems. The I/O Controller functions as a watchdog for the
Pentium, forcing the system into a nonfunctional safe state if the
Pentium discontinues its interprocessor communication.
5.4.2.5 Operating System Software (Host)
The host control software (operating system) is loaded into the 64
MB programmable read only Compact Flash Memory. This
memory resides piggy-backed to the SBC.
The purpose of the operating system is to:
• Gather data from the Input/Output, Blood Pump(s) and UF-
Proportioning controller sub-systems, and output control
functions to the various controller sub-systems.
• Input data from User Interface Touch Screen.
• Monitor the data for violation of alarm limits and unsafe
operating conditions, and set the appropriate program alarm
condition indicators.
• Update the display data to the video display portion of the
user interface.
• Save and retrieve calibration constants in the nonvolatile
memory (SRAM on the Memory board), then use the
calibration constants during Instrument operation. Refer to
Section 5.4.7.
• Monitor the arterial and venous pressures, and generate
alarms when they violate their alarm limits. The alarm
response includes clamping of the line clamp (via the I/O
Controller) and stopping the blood pump (via the Blood
Pump Controller).
• Calculate the TMP (transmembrane pressure) by
subtracting the dialysate pressure from the venous pressure.
Compare the results with the TMP alarm limits, generating
an alarm if a violation is detected.
• Serve as a watchdog, ensuring that the Pentium and the
three 8040 controllers (one each on the BP, I/O, and UF-
Proportioning Controller boards) are functioning.
• Perform the Shutdown Self Test.
• Perform the Pretreatment Self Test.
• Control the active Instrument modes: Calibration, Rinse,
Self Test, Prime, Dialyze, Heat Clean, Cool Down or
Chemical Disinfection.
157-1278-912 Rev A 5-21
November 2003
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