RS-485 - data transmission standard
RS485 network can include up to 32 receivers and 32 transmitters. The maximum cable length is 1200 m. The most common topography for this standard is a half-duplex bus structure (allowing the transmission of signals in both directions but not simultaneously). |
The differential transmission between the transmitter and the receiver eliminates the external interference affecting both signal lines. Maximum bandwidth is 35 Mb/s at a maximum distance up to 10 m and 100 kb/s at a distance of up to 1200 m. |
In CCTV monitoring, RS485 is mostly used to control the rotary cameras and cameras with automatic zoom. Splitters with optical couplers are used to protect the device connected via a RS485 interface against overvoltage. They allow to use a star topology instead of a standard bus topology. |
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