Legacy® PLUS - Smiths Medical

Reference
Section 5: Reference
Software Safety Features
Hardware-related Software Safety Features
Program Memory Check
At power up and at regular intervals thereafter, the program memory is
tested by calculating a Cyclic Redundancy Code (CRC) on the program and
then comparing it with the CRC stored with the program.
If the stored and calculated CRCs do not match, the software will display
a system fault screen, turn on a continuous two-tone audible alarm, and
stop all medication delivery.
RAM Memory Check
At power up, the random access memory is checked. A series of bit patterns
is written to and read from each address in the RAM. If the read
data is different from the written data, the software will display a system
fault screen, turn on a continuous two-tone audible alarm, and stop all
medication delivery.
Motor Circuit Check
At power up and at regular intervals thereafter, the motor circuit is
checked to ensure that no power is being applied to the motor unless
the motor is actually on. If the software detects power being applied to
the motor at any other time, it will sound a continuous two-tone audible
alarm and will no longer attempt to deliver medication. During every
pump activation, the software checks to see whether the motor completes
one activation. If the motor fails to turn, or fails to complete a cycle, the
software will display a system fault screen, turn on a continuous twotone
audible alarm, and stop all medication delivery.
Keyboard Encoder Check
Every time the software receives data from the keyboard encoder, it is
checked. If the data is not a valid key press, the software will disregard
the key press. The keyboard is designed with redundant switches for
‹ and ⁄. The software must detect that both switches are activated
before taking any action.
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