7
Disclaimer
Before you supply the whole system with power, carefully
check all connections for correctness! The GBS-Elektronik
GmbH is not liable for errors and damages caused by wrong
use and improper installation of the Serial Watchdog module.
Furthermore the GBS-Elektronik GmbH is not liable for indirect
or subsequent damages due to wrong installation and
malfunction of the Serial Watchdog.
1.2 Building a 24V DC watchdog monitored system with UPS
Figure 1.2 shows a typical 24V DC watchdog monitored computer
system with UPS. In this application a 230V AC output UPS is combined
with an additional 230V AC / 24V DC converter. Instead of this
combination a single 24V DC output UPS can be used. In most cases it
is very useful to directly connect the watchog's power supply with the
power relay's middle contacts.
1.3 Using the reset switch of the computer
Another way is to use the computer's reset switch to initialize a reboot.
This is only possible with computers which are equipped with a usable
reset switch. In this case the power relay of the watchdog is not used to
cut the power supply of the computer, but it closes the reset switch for a
short time. Note that this works perfectly with a lot of computers, but
there are also models (particularly newer ones) which are sometimes
immune against a reset. In some special cases (evil hang-up) this
computers do not respond to the reset signal.