35c. For too long signal wires, 120Ω should be parallel connected between A, B lines on thefar end to reduce reflection and guarantee the signal quality.d. “485 A, B” of DVR cannot parallel connect with “485 port” of other device.e. The voltage between of A,B lines of the decoder should be less than 5v.4. Please make sure the front-end device has soundly earthed.Improper grounding may result in chip damage.3.7.1 Alarm Input and Output DetailsImportantPlease refer to the specifications for the alarm input and output channel amount.Do not merely count the alarm input and out channel amount according to the portson the rear panel.Figure 3-11,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16ALARM 1 to ALARM 16. The alarm becomes active in low voltage.In the second line,from the left to theright:NO1 C1,NO2 C2,NO3 C3,NO4 C4,NO5 C5,NO6 C6.There are six groups of normal open activation output (on/off button)CTRL 12V Control power output. For external alarm, you need to close thedevice power to cancel the alarm.Voltage current;500mA.+12V Rated current.Voltage current;500mA.