Double Dome PTZPZ9, Installation Manual

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Appendix 2 RS485 Bus Common Sense
1. RS485line Basic Features
According to RS485 main line standard, RS485 resistance is 120Ω control line,
maximum load is 32 pieces available, (including main control and controllers
instrument).
2. RS485 Transmit Distance
When you use 0.56mm(24AWG)as control line, baud rate and maximum
distance are as bellow:
Baud rate Maximum distance
2400Bps
1800meters
4800Bps
1200meters
9600Bps
800meters
3
．
Connect Method and Terminal Resistance
●
RS485stand requires to use daisy chain connection. Two end
must connect 120Ω terminal resistance.
（
as picture a
）
simple
connection can see picture b, but “D” distance is less than 7 meters.
1# 2# 3# 4# 32#
120Ω 120Ω
Picture
a
1# 2# 3# 31#
控制器
120Ω 120Ω
A+ B-
B-
A+
D
Picture
b
●
As picture b, JP help RS485 line 120Ω terminal resistance to choose
bridge. In order to avoid 485 signal on the 485 line occur reflection. Usually
connected 120Ω termination resistor to the endpoint to avoid signal reflection,
and middle equipment must be disconnected from the terminal resistance