Modbus, Johnson n2, Lonworks – Carrier 50HCQ04---12 User Manual

Page 11

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11

SW3 Protocol Selection

PROTOCOL

DS8

DS7

DS6

DS5

DS4

DS3

DS2

DS1

BACnet MS/TP

(Master)

Unused

OFF

OFF

OFF

ON

OFF

Select Baud Select Baud

Modbus

(Slave)

Unused

OFF

OFF

ON

ON

OFF

Select Baud Select Baud

N2

(Slave)

Unused

OFF

OFF

OFF

ON

ON

OFF

OFF

LonWorks

Unused

ON

ON

OFF

ON

OFF

OFF

ON

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. 11 -- RTU--OPEN SW3 Dip Switch Settings

C10815

Fig. 12 -- RTU--OPEN Address Switches

C10816

Fig. 13 -- Network Wiring

Modbus

The RTU--OPEN module can speak the Modicon Modbus

RTU Protocol as described in the Modicon Modbus

Protocol Reference Guide, PI----MBUS----300 Rev. J. The

speed of a Modbus network can range from 9600 to 76.8K

baud. Physical Addresses can be set from 01 to 99.

Johnson N2

N2 is not a standard protocol, but one that was created by

Johnson Controls, Inc. that has been made open and

available to the public. The speed of N2 network is

limited to only 9600 baud. Physical Addresses can be set

from 01 to 99.

LonWorks

LonWorks is an open protocol that requires the use of

Echelon’s Neuron microprocessor to encode and decode

the LonWorks packets. In order to reduce the cost of

adding that hardware on every module, a separate

LonWorks Option Card (LON--OC) was designed to

connect to the RTU--OPEN.
This accessory card is needed for LonWorks and has to be

ordered and connected using the ribbon cable to plug J15.

The RTU--OPEN’s baud rate must be set to 38.4k to

communicate with the LON--OC. The address switches

(SW1 & SW2) are not used with LonWorks.

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