PowerLogix COM128 installation and operation guide RS-485 STRAIGHT-LINE Topology

Figure 4.3.3a RS-485 Straight-Line and Loop Topologies

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RS-485 STRAIGHT-LINE TOPOLOGY

			Last
			RS-485	Device
			(End	Point)
	RS-485 PORT	RS-485 PORT	RS-485 PORT
SHLD	SHLD		SHLD

			COM128
	RS-232 to RS-485 Converter				SHLD	RS-485 Cable		RT Termination Resistor
	DCE			PORT D		AWG 22 shielded twisted pair.	Overall length: 4000 ft. maximum.	See Section 4.3.3.
Computer	PORT	RS-232
	PORT		485-RS	PORT C				RS-485	Device
or Modem	D T E							Last
				PORT B				(End	Point)
						RS-485 PORT	RS-485 PORT	RS-485 PORT
				PORT A		SHLD	SHLD	SHLD

RT Termination Resistor

See Section 4.3.3.

RS-485 LOOP TOPOLOGY

	RS-485 PORT	RS-485 PORT	RS-485 PORT
SHLD	SHLD	SHLD	SHLD

			COM128
	RS-232 to RS-485 Converter				SHLD	RS-485 Cable
	DCE			PORT D	AWG 22 shielded twisted pair. Overall length: 4000 ft. maximum.
Computer	PORT	RS-232
	PORT		485-RS	PORT C
or Modem
	D T E
				PORT B
					RS-485 PORT	RS-485 PORT	RS-485 PORT
				PORT A	SHLD	SHLD	SHLD

COM128 Installation and Operation Manual

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