B&B Electronics manual Serial Port Connections, RS-485 Terminal Block Connections

Serial Port Connections

To communicate with the 485SDA10 module, it must be connected to an RS-422/RS-485 serial port. The 485SDA10 works with 2-wire or 4-wire RS-485. The unit automatically detects baud rates from 1200 to 9600. A data format of 8 data bits, 1 stop bit and no parity is used. Connections are made using terminal blocks. Table 2.2 shows the terminal blocks and their functions.

Table 2.2 - RS-485 Terminal Block Connections

TB		485SDA1
Label	Signal	0 Function	Notes
TD(A)	Transmit Data (A)	Output	Connection is required. [Loop
			to RD(A) for 2-wire hookup]
TD(B)	Transmit Data (B)	Output	Connection is required. [Loop
			to RD(B) for 2-wire hookup]
RD(A)	Receive Data (A)	Input	Connection is required. [Loop
			to RD(A) for 2-wire hookup]
RD(B)	Receive Data (B)	Input	Connection is required. [Loop
			to RD(B) for 2-wire hookup]
GND	Ground	-	Connection for Signal GND
			and Power Supply GND.
+12V	+12 V DC Power	Input	Connection is required.

A typical 2-wire RS-485 connection is shown in Figure 2.3 and a typical RS-422 (or RS-485) 4-wire is shown in Figure 2.4.

NOTE: The 485SDA10 labels the data lines with “A” and “B” designators (per EIA RS-485 Specification). However, some RS-

485 equipment used “+” and “-“ as designators. In most cases the “A” line is the equivalent of the “-“ line and the “B” line is the equivalent of the “+” line. With an RS-485/422 system there are other factors that require consideration, such as termination and turn-around delay. For more information refer to the RS-485/422 Application Note (included in packing).

10 485SDA103798 Manual

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