Xantrex Technology Freedom SW Series manual See NOTE below, 975-0704-01-01Revision A

Wiring the RS 485 Modbus Connector for Data Communication

Modbus versus Xanbus

Connecting the Conext ComBox with other Modbus Devices

The RS 485 Modbus connection and Xanbus cable connection provide data communication from the network and devices to the Conext ComBox. Communication with Modbus devices is handled through the RS 485 or 10/100 Ethernet connection on the Conext ComBox while communication with Xanbus components occurs through the Xanbus ports of Xanbus-enabled devices.

In the Modbus implementation, the Conext ComBox acts as a slave to an RS 485 master device. The RS 485 connection to the Conext ComBox allows communication between the Xanbus network and the master device. This enables Conext devices to link to third-party software and building management systems.

If a Modbus device, including the Conext ComBox, is installed as the last device in a daisy chain, a 120 ohm terminator must be used because they do not have an internal terminator for the RS 485 network. When inserting two wires in one terminal, as in the case of daisy-chained RS 485 Modbus devices, use smaller gauge wires. See the following example.

Note: Turn off all Modbus and other devices prior to wiring the connectors.

Modbus

Device 1

RS 485

Connect the RS 485 connector to the RS 485 port.

See NOTE below.

Modbus

Device 2

Modbus Device 3

D1

D0 Shield

24 V 

Power

Supply

120-ohm

Terminator

RS 485	Modbus
120-ohm	Device 4
Terminator

975-0704-01-01 Revision A 2–7