Chapter 2 - Connections

This chapter will cover the connections required for the 485SDD16. There are three sets of connections: digital I/O, serial port, and power supply. Do not make any connections to the 485SDD16 until you have read this chapter.

Digital I/O Connections

Connections to the I/O lines are made through the DB25S (female) I/O port connector. Refer to Table 2.1. See Chapter 5 for I/O interfacing examples.

Digital Inputs

The digital input lines are CMOS/TTL compatible and can handle voltages from 0Vdc to +5Vdc.

Digital Outputs

The digital output lines have a maximum voltage of +5Vdc and are CMOS compatible.

Ground

This pin should be connected to the external digital devices ground.

Table 2.1 - 485SDD16 I/O Port Pinout

DB-25S

 

 

DB-25S

 

Pin #

Function

 

Pin #

Function

 

 

 

 

 

1

No connection

 

14

I/O #15

2

No connection

 

15

I/O #14

3

No connection

 

16

I/O #13

4

No connection

 

17

I/O #12

5

No connection

 

18

I/O #11

6

No connection

 

19

I/O #10

7

Ground

 

20

No connection

8

+12Vdc Input

 

21

I/O #9

9

I/O #0

 

22

I/O #8

10

I/O #1

 

23

I/O #7

11

I/O #2

 

24

I/O #6

12

I/O #3

 

25

I/O #5

13

I/O #4

 

 

 

485SDD16-1005 Manual

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Serial Port Connections

In order to communicate to the 485SDD16 module it must be connected to an RS-422/RS-485 serial port. The 485SDD16 will work on a 2-wire or 4-wire RS-485 multi-node network. Refer to B&B Electronics’ free RS-422/485 Application Note for more information. 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

 

 

Signal

 

TB

 

Direction at

Notes

Label

Signal

485SDD16

 

 

 

 

FR

Frame

-

Connection for frame ground.

GND

Ground

 

 

TD(A)

Transmit

Output

Connection is required. [Loop to

 

Data (A)

 

RD(A) for 2-wire hookup]

TD(B)

Transmit

Output

Connection is required. [Loop to

 

Data (B)

 

RD(B) for 2-wire hookup]

RD(A)

Receive

Input

Connection is required. [Loop to

 

Data (A)

 

TD(A) for 2-wire hookup]

RD(B)

Receive

Input

Connection is required. [Loop to

 

Data (B)

 

TD(B) for 2-wire hookup]

+12V

+12 Vdc

Input

Connection is required.

 

Power

 

 

GND

Ground

-

Connection for Signal GND and

 

 

 

Power Supply GND.

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

2.4.Note that the 485SDD16 data line labels use “A” and “B” designators (per EIA RS-485 Specification). However, some RS-485 equipment uses “+” and “-“ as designators. In almost all cases, the “A” line is the equivalent of the “-“ line and the “B” 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 B&B Electronics’ free RS-422/485 Application Note.

6485SDD16-1005 Manual

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PH (815) 433-5100 -- FAX (815) 433-5104

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B&B Electronics manual Digital I/O Connections, 485SDD16 I/O Port Pinout, Serial Port Connections