© Copyright Qvis® All documentation rights reserved. 35e. When you are connecting two DVRs or you are connecting one DVR and one other device,please use a relay to separate them,2. Alarm outputTo avoid high current, which may result in relay damage, the alarm output port should not beconnected to high power load directly (It should be less than 1Amp). Please use the co-contactorto make sure there is a connection between the alarm output port and the load.3. How to connect PTZ decodera. Ensure the decoder has the same grounding as the DVR, otherwise you may not control thePTZ. Shielded twisted wire is recommended and the shielded layer is used to connect to thegrounding.b. Avoid high voltage. Ensure proper wiring and some surge protection measures.c. For signal wires that are too long, 120Ω should be parallelly connected between A, B lines onthe far end to reduce reflection and to guarantee signal quality.d. “485 A, B” of DVR cannot parallelly connect with a “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 been soundly earthed.Improper grounding may result in circuit damage.3.7.1 Alarm Input and Output DetailsYou can refer to the following sheet X for alarm input and output information.Important:Please refer to the specifications for the alarm input and output channel amount. Do notmerely count the alarm input and out channel amount according to the ports on the rearpanel.3.7.1.1 iApollo HDRT HDThe 8-channel series product interface is shown as below. See Figure 3-1.Figure 3-1AB cableconnection