Wiring the Network and Connecting the Computer

2.2.3 RS-485 Network

If your computer is equipped with an RS-485 interface, connect to the controller network in accordance with the instructions provided with that option card.

If you plan to use a serial (COM) port to connect to your network, install an RS-232-to- RS-485 converter on the port (see diagram below). A suitable converter is available from Omega.

RS-232/RS-485 converter; Omega part number 223A001U01*

Up to 2000 ft

1

6

2

(B)

(A) 7

 

13

14

3

 

8

4

 

9

 

11

12

5

 

 

 

 

10

Other controllers

 

 

 

 

 

 

 

* Converter is supplied with a wallplug-mounted power

To

 

transformer.

 

Controller

 

 

 

(A)

 

 

Terminal 14

 

 

To

(B)

 

 

Controller

 

 

Terminal 13

 

Data cable assembly DB 9 to DB 25, or DB 9 to DB 9 depending on your computer

Computer

RS-232 port

Wire directly to screw terminals on converter. B on converter goes to A on unit, A on converter goes to B

+12 V GND

RD(B)

RD(A)

TD(B)

TD(A)

RS-485 Communication:

One-to-many connection between an RS-232 port (with converter) and multiple

controllers; if the computer has an RS-485 port, no converter is needed

2-3

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Omega Engineering #M3350/0101 manual 3 RS-485 Network, Wiring the Network and Connecting the Computer