Communication Wiring - Protocols

General —

Protocols are the communication languages spoken by control devices. The main purpose of a protocol is to communicate information in the most efficient method possible. Different protocols exist to provide different kinds of information for different applications. In the BAS application, many different protocols are used, depending on manufacturer. Protocols do not change the function of a controller; just make the front end user different.

The RTU Open can be set to communicate on four different protocols: BACnet, Modbus, N2, and LonWorks. Switch 3 (SW3) on the board is used to set protocol and baud rate. Switches 1 and 2 (SW1 and SW2) are used to set the board’s network address. See Fig. 67 and 68 for protocol switch settings and address switches. The 3rd party connection to the RTU Open is through plug J19. See Fig. 69 for wiring.

NOTE: Power must be cycled after changing the SW1-3 switch settings.

Refer to the RTU Open Controller Integration Guide (Catalog No. 11-808-428-01) for more detailed information on protocols, 3rd party wiring, and networking.

SW3 Protocol Selection

PROTOCOL

DS8

DS7

DS6

DS5

DS4

DS3

DS2

DS1

 

 

 

 

 

 

 

 

 

BACnet MS/TP

Unused

OFF

OFF

OFF

ON

OFF

Select Baud

Select Baud

(Master)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Modbus

Unused

OFF

OFF

ON

ON

OFF

Select Baud

Select Baud

(Slave)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

N2

Unused

OFF

OFF

OFF

ON

ON

OFF

OFF

(Slave)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

LonWorks

Unused

ON

ON

OFF

ON

OFF

OFF

OFF

 

 

 

 

 

 

 

 

 

NOTE:

 

 

 

 

 

 

 

 

DS = Dip Switch

 

 

 

 

 

 

 

 

BACnet MS/TP SW3 example shown

Baud Rate Selections

BAUD RATE

DS2

 

DS1

 

 

 

 

 

 

 

 

9600

OFF

 

OFF

 

 

 

 

 

 

 

 

19,200

ON

 

OFF

 

 

 

 

 

 

 

 

38,400

OFF

 

ON

 

 

 

 

 

 

 

 

76,800

ON

 

ON

 

C07166

 

 

 

 

 

 

 

Fig. 67 - RTU Open SW3 Dip Switch Settings

 

 

 

48HC

C10815

Fig. 68 - RTU Open Address Switches

Fig. 69 - Network Wiring

C10816

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Carrier 48HC installation instructions Communication Wiring Protocols, General

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