Special Operating States; Reaction On Bus Voltage Failure/Recovery, Download And Ets Reset; Bus Voltage Failure; Bus Voltage Recovery - ABB i-bus KNX ABA/S 1.2.1 Product Manual

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ABB i-bus KNX
Function
4.6

Special operating states

4.6.1

Reaction on bus voltage failure/recovery, download and ETS reset

The device's reaction on bus voltage failure/recovery, download and ETS reset can be set in the device
parameters.
If the power fails (24 V DC or PoE), the device safeguards certain internally calculated values, e.g.
staircase lighting time or the integral value of the PID controller. The device continues to operate for at
least 5 seconds and typically up to 20 seconds using backup power. If power is restored during this time,
the device continues to operate normally.
If the power failure exceeds the backup time, the device shuts down safely.
When power has been restored, the device restarts. The KNX inputs behave as per their parameters, i.e.
an initial value is set or values are received. See also KNX inputs (KNX IN).
The internal device clock status remains "invalid" until the device receives the time and date via the
corresponding KNX group objects.
4.6.1.1

Bus voltage failure

Bus voltage failure describes the sudden drop in/failure of the bus voltage, e.g. due to a power failure.
If the bus voltage fails but the power supply is running, the device continues to operate normally and saves
all internal values. Bus-dependent calculations such as the Calendar or Timer function also run normally,
but no telegrams are sent.
4.6.1.2

Bus voltage recovery

Bus voltage recovery is the state after bus voltage is restored after failing previously due to a bus voltage
failure.
On bus voltage recovery, group objects are updated to their current values. However, they are not sent to
the bus during the update. After the update, group objects behave normally again according to the settings
on the KNX outputs. See also KNX outputs (KNX OUT).
ABA/S 1.2.1 | 2CDC509086D0201 23