Dante DLM1971, Инструкция по установке и эксплуатации

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5
RS-485 and video port can pass 10/700us 1500V differential-mode and
4000Vcommon-mode lightning strike and surge testing. Which reach ITU
－
－ －
－
T K21
－
－ －
－
2003
international lightning proof standard and GB9043 standard. But it can’t prevent direct
lightning stroke, will need additional device.
4.Requirements for the connect cables
Requirements for the 24VAC power supply cable
Normally, the power wires have some resistance. There is some loss during voltage
transmission. The longer the wire is and the smaller the wire diameter is the worse loss will be.
Please refer to following wire diameter and distance requirement in order to avoiding the abnormal
work caused by insufficient voltage.
Power supply cable
diameter
0.5mm²(20#)
1.0mm
²(18#)
1.5mm
²(16#) 2.5mm²(14#)
Dome camera distance
11m(37ft) 18m(60ft) 29m(95ft) 46m(152ft)
Requirements for the video cable
The video wire also has inner loss as the power wire. The more the wire is and the small the
specification is, the worse loss it will be. The high the signal frequency is, the obvious the loss is.
The normal video wires models and the MAX. Transmission distance is listed in following table:
Video cable model Max. transmission
distance
Video cable model Max. transmission
distance
75-2 About 150m 75-5 About 370m
75-3 About 200m 75-7 About 500m
75-4 About 270m 75-9 About 680m
Requirements for RS-485 control cable
RS-485 cable transmission distance is relative to the cable diameter, transmission rate and
electro-magnetic interference condition. For examples: with a 1.0mm² twisted pair, if under 9600b/s
transmission rate, the longest transmission distance is 800M; if under 4800b/s transmission rate,
the longest transmission distance is 1000M; and if under 2400b/s transmission rate, the longest
transmission distance is 1200M.
Sometimes the installer use star connection mode, which doesn’t meet the industry standard
for RS-485 requirement. If the devices distance is far, it may cause signal reflect, reduce
Anti-interference capability and the camera will lose normal control. The suggestion is to parallel
connect a 120 ohm resistance at the fastest RS-485 anode and cathode; or adopt RS-485 distributor.