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Technical Reference Manual, General
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RAM memories
Nonvolatile memories
Microcontroller and program
execution
A/D converter, multiplexer and
amplifiers
Setting values
HMI (display)
Power supply module
Output amplifiers and relay
coils
When the self-supervision detects a fault, different measures are taken depending on
the severity of the fault. If the fault is fatal, the microcontroller tries to get the system
to work by restarting ten times. If this attempt is not successful, a signal about the
internal relay fault (IRF) is linked to the output relay. Provided that the unit is
operating normally, the information about the fault is sent as an event
"IRF activated" (E31) over the serial communication and the green READY LED
on the front panel starts blinking. An indication about the character of the fault is
also shown as a textual message on the display.
If the fault is considered too dangerous to maintain normal protection, an inoperative
IRF state is entered and no output relay operations are allowed. On the other hand
if, for example, one output relay is found faulty and the others healthy, normal
operations targeted to a healthy relay are allowed.
Even a total breakdown of the relay, for example, on loss of power supply, will be
detected as the IRF relay operates in a fail-safe mode, causing a signal when the
relay drops off. The serial communication will also indicate loss of contact to the
module. When the relay is in the IRF state, it tries to recover by restarting every five
minutes.
As long as the fault remains, the relay continues to perform internal tests. Should the
fault prove to be of temporary nature, normal operation is recovered after restart and
an event "IRF reset" (E30) is sent over the serial communication.
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The self-supervision signal output operates on the closed circuit principle. Under
normal conditions the output relay is energized and the contact gap 3-5 is closed.
Should the auxiliary power supply fail or an internal fault be detected, the contact
gap 3-5 is opened.
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Write and read of all memory
locations
Checksum
Internal watchdog
Reference voltage
Checksum, correct values
Visual inspection
Measurement of supply
voltages
Feedback from the relay coils 1 min
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40 B / 200 ms
When data is fetched
100 ms
1 min
1 min
On connection of supply
voltage
1 min