User Guide

55
RELAYS AND LEDS
Relays and LEDs selftests are executed as follows:
First all of the relays and LEDs are switched off, then they are
switched on one at a time for a few seconds and cyclically.
User can interrupt the otherwise endless cycle, as indicated
by the scrolling message, by pressing a key.
Note Relays and LEDs test has to be carried out with the relay
contacts disconnected from external plant devices.
WATCHDOG
When a dead loop condition is detected a reset is automati-
cally invoked.
The effectiveness of watchdog capability can be tested through
one of the special setup items. This test consists of executing
a dummy dead loop that causes watchdog reset signal to be
generated.