This is a demonstration of using Modbus over RS485 to control a 16 channel (relay) board by an Arduino Mega using the ArduinoModbus library. Full details and code are available on this Instructable. [ Ссылка ]
Here are the parts used in this video.
Relay board that uses RS485 Modbus controls. These are available in 4,8,16 and 32 relay boards.
Here is one example
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The Arduino does not have a serial port that talks RS485. One serial to RS485 board is required.
I used one like this
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An Arduino Mega
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