DRN series is a 12 or 24 VDC redundant operation system. When two DRN series are working together and one of them is malfunction, the other one can supply full power. This can prevent high tier system causes data lost or equipment control error and, furthermore, loss of life and property because of faulty power. Buzzer of DRN series will alarm when one of them is not functional and will send relay RDY signal. (Customer can make specialized alarm system with this 1A relay contact.) When power source is unstable, V1 or V2 indicator will point out which power source is bad. DRN series can easily install with din rail / standard enclosure power supply, and do not need unconventional build-in RDY signal power supply because DRN series builds in this feature. The design can let customer use with commercially available power supply, lowering inventory and cost.