Honeywell TB7600 User Manual download pdf (Page 4)

BACNET INTEGRATION MANUAL FOR TB7600 SERIES THERMOSTATS

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NETWORK CONFIGURATION

EIA-485 networks use a daisy chain configuration. A daisy chain means that there is only one main cable and every network

device is connected directly along its path.

Fig. 1 illustrates two improper network configurations and the proper daisy chain configuration.

Other methods of wiring an EIA-485 network may give unreliable and unpredictable results. There are no troubleshooting

methods for these types of networks. Therefore, a great deal of site experimentation may have to be done, making this a difficult

task with no guarantee of success. Honeywell will only support daisy chain configurations.

Fig. 1. Three different network configurations: star, bus, and daisy chain.

Only the daisy chain configuration is correct for an EIA-485 network.

Maximum Number of Devices

A maximum of 64 nodes is allowed on a single daisy chain segment. A node is defined as any device (controller, thermostat,

repeater) connected to the RS485 network. Terminators do not count as a node.

NOTE: Biasing is not required with this series of devices.

To determine the number of nodes on a network, add the following:

• One node for each device, including controller

• One node for each repeater on the chain

For the example in Fig. 2, we have one node for the controller, plus 4 for the thermostats, for a total of 5 nodes.

Fig. 2. Five nodes network example.

If you have more than 64 devices, then repeaters are required to extend the network.

M32571

DAISY CHAIN

CONFIGURATION

BUS CONFIGURATION

STAR CONFIGURATION

EOL

NODE 2

NODE 3

NODE 4

NODE 5

EOL

NODE 1

END OF LINE RESISTOR DOES

NOT COUNT AS A NODE

M32572

LEGEND

EOL: END OF LINE RESISTOR

SC: SUPERVISORY CONTROLLER

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Honeywell TB7600 User Manual Page 4