Black Box RS422/485, RS-232/422/485 manual Description RS-485 RS-422, Switch SW3 Settings

DUAL- AND QUAD-PORT USB HUBS

Table 4-2. DIP-switch SW4 settings.

Switch	Switch			Port		Description		RS-485	RS-422
Setting	Number
L	SW4-1	1			TX+	to RX+	ON	OFF
L	SW4-2	1			TX-	to RX-	ON	OFF
T	SW4-3	1			Termination		ON	ON
PD	SW4-4	1		1K Pull-Down			ON	OFF
PU	SW4-5	1		1K Pull-Up			ON	OFF
L	SW4-6		2		TX+ to RX+		ON	OFF
L	SW4-7		2		TX- to RX-		ON	OFF
T	SW4-8	2			Termination		ON	ON
PD	SW4-9	2		1K Pull-Down			ON	OFF
PU	SW4-10	2		1K Pull-Up			ON	OFF

L = Loops TX+ to RX+ or RX- to TX- for two-wire operation.

T = Adds a 120-ohm termination resistor between RX+ and RX-.

PU = Pull-up. Adds a 1 K-ohm pull-up resistor to RX+.

PD = Pull-down. Adds a 1 K-ohm pull-down resistor to RX-.

Switch SW3 Settings

To select RS-485 mode (4-wire or 2-wire operation) or RS-422 mode (4-wire operation), set the DIP switch labeled SW3 on the circuit board. (See Figure 4-2 and Table 4-3.)

Figure 4-2. RS-422/485 interface configuration.

NOTE

Switch positions SW3-1 and SW3-2 are for Port 1 and switch positions

SW3-3 and SW3-4 are for Port 2.

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