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Operational faults
The following list shows how the controller reacts depending on which sensor fails:
4
Outdoor sensor AF: When the outdoor sensor fails, the controller uses a flow temperature
set point of 70 °C. The boiler pumps are switched on and the control valves of the return flow
boost are opened to ensure frost protection.
4
Flow sensor VFg: Both boilers are switched off immediately.
4
Flow sensor VF1, VF2: The affected boiler is switched off. The other boiler takes over.
4
Return flow sensor RüFg: The controller continues to function without the differential temper-
ature control using variable weighting factors.
4
Boiler return flow sensor RüF: The controller continues to function without the return temper-
ature limitation. If the affected boiler is switched on, the boiler pump is switched on and the
control valve receives a constant signal.
4
Storage tank sensor SF1/SF 2: When one of the sensors fail, storage tank charging no lon-
ger takes place.
4
Boiler K1, K2 (binary inputs SM_K): The affected boiler and the associated pump are
stopped.
4
Pumps (binary inputs SM_P): The affected boiler and the associated pump are stopped.
9.3
Displaying the lead/collective error alarm
The lead is indicated over BA2 when the function block is active:
4
Lead 1: BA2 = OFF
4
Lead 2: BA2 = ON
The binary output BA2 is set in the event of an error when the function block is not active. Errors
are still displayed by "Err" in the info level.
Function
Displaying lead/collective alarm
9.4
Error status register
The error status register is used to indicate controller or system errors. In modem operation with
Dial-up also upon corrected fault function, any change in state of the error status register causes
the building control station to be dialed.
The error status registers are displayed in InF8 level. By default the error status register FSR1
(holding register 60) is displayed. Keep
both displays, function blocks Fb20 to Fb23 are set when a bit is set in the error status register
not being displayed.
62
EB 5474 EN
WE
Configuration
OFF
Co5 -> Fb11
pressed to display FSR2 (holding register 61). In
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