GE b30, Technical Reference Manual

Page: 153 / 252

Set/Test
5-27
Document no. 2044677-001
5 Set/Test
The power supply unit contains a watchdog
circuitry, which needs refreshment at every
1.5 seconds. If the refreshment did not occur,
the watchdog circuitry will reset the main
CPU. In normal operation, the main CPU
refreshes the watchdog circuitry at every 0.2
seconds.
The purpose of the watchdog circuitry is to
restart the monitor, if there was a serious
malfunction. This feature is useful in two
cases: when the main CPU is not able to
control the monitor, or when the CPU
controls the monitor but detects a serious
malfunction. Watchdog tests check proper
functionality of the watchdog circuitry in
various conditions.
Watchdog test ensures directly that the
watchdog of the power unit functions
properly. Choosing this test prevents the
watchdog circuitry from refreshing and
shows running seconds with an accuracy of
0.1 seconds.
The test should have the following result when the watchdog circuitry is
working properly: The monitor will restart after 1.5 seconds from the start
of the test. In malfunction: ‘>20 s’ is displayed, and the test will be
interrupted. In this case, the fault is in the watchdog circuitry of the power
unit.
WD by Overload test ensures the functionality of a feature, where the
software controls the monitor, but detects an overload situation in the main
CPU.
The test should have the following result when the feature is working
properly: The monitor will restart after 15 seconds from the start of the test.
Factory Reset restores the factory default settings and clears the data
memories. Factory reset should be run if the monitor software is replaced
or if the SRAM/Timekeeper battery is replaced.