6. Temperature Control
board for comparison against the primary temperature
alarm limits as well as temperature compensation for the
primary conductivity.
4. The I/O Hydraulics Power board reads the temperature
from the primary temperature probe.
5. The I/O Controller board reads and converts into a digital
signal the primary (dialysate) temperature probe signal
from the I/O Hydraulics Power board, and sends this
information to the SBC.
The Primary temperature probe is located in the dialysate
manifold.
6. The I/O Controller board provides technician-adjustable
high and low alarm limits indirectly (via the SBC)
triggering audible and visual alarms.
7. The I/O Controller generates a high or low temperature
alarm (user-selectable maximum between 39 and 41°C, and
minimum between 34 and 36°C) when the primary
temperature passes either threshold.
8. The SBC reads the the primary (measured) temperature
from the I/O Controller, and alarm indication from the I/O
Controller, and displays them in the LCD. ALARM is
displayed by the SBC in the LCD, above the temperature
window.
9. Under the command of the I/O Controller board, the I/O
Hydraulics Power board directly deactivates the bypass
valve during a primary temperature alarm, therefore
removing flow to the dialyzer.
6.4 AUTOMATIC SAFETY TESTS
Since the UF-Proportioning microcontroller is responsible for
controlling the temperature, the I/O microcontroller provides an
independent safety system. The safety system contains three major
components whose functions are verified during self test at the
beginning of each treatment. These are:
The I/O Controller's ability to measure the dialysate
temperature using the primary conductivity probe
thermistor
The I/O Controller's ability to alarm off of a temperature
outside of the SBC supplied alarm limits
The I/O Controller's ability to deactivate the bypass valve
157-1278-913 Rev A 6-7
November 2003
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