User Manual

Alarm management
Effects of BACnet properties on alarm response
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CM110664en_07 139 | 351
6. The fault has been cleared. When DPMon.Dstb = 0, then Cmd.EnSfty → 0 and hence Cmd.PrVal →
Cmd.ValPgm=1, that is, the fan motor is enabled. Then, with Cmd.TraSta = 1 (transient state), the fan
ramp-up time is allowed to expire, that is, DPMon.RefVal is held at 1 during the transient state. Only
after expiry of the ramp up time does DPMon.RefVal revert to 0.
7. The ventilation system is already running (from step 6 on), that is, the fan blades start rotating, the
pressure builds up and the differential pressure monitor detects delta p = X again, that is, DPMon.PrVal
→ 1. The alarm monitoring function is active again. After expiry of the time [TiMonDvn], this determines
that there is no alarm condition present, because [DPMon.PrVal(0) <> DPMon.RefVal (1)]. The system
then operates 100% correctly as described under step 1 above.
To simplify the time chart shown above, the connection to DPMon.EnAlm has not been included.
9.3 Effects of BACnet properties on alarm response
BACnet properties in function blocks
I = Input
O = Output
V = Value