Distech Controls ECB-VAV, User Manual

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16 Network Guide
Baud Rate
Most devices will have a range of baud rate settings and possibly an AUTO setting that
detects the baud rate of other devices transmitting on the data bus and adjusts the baud rate
of the device accordingly. Typical baud rates are 9600, 19 200, 38 400, and 76 800. The baud
rate setting determines the rate at which data is sent on the BACnet MS/TP data bus.
All devices on the data bus must be set to the same baud rate. Therefore, the chosen baud
rate must be supported by all devices connected to the data bus.
The recommended baud rate for Distech Controls' devices is 38 400.
We recommend that you:
• Set the baud rate of two controllers on a BACnet MS/TP Data Bus Segment to the same
baud rate to provide failover protection.
For example, set the baud rate of the EC-BOS (if equipped) and one other controller to 38
400 baud. If the EC-BOS becomes unavailable and there is a power cycle, the controller
will set the baud rate for the BACnet MS/TP Data Bus.
• Set all other devices to automatically detect the baud rate, if this option is available.
Figure 1: Setting the Baud rate on two Controllers on a BACnet MS/TP Data Bus Segment for Failover
Protection
To set the baud rate for ECB series controllers, see Setting the Baud Rate for ECB-Series
Controllers (optional) on page 101.
About Setting Built-in EOL Terminations
All controllers use both jumpers or DIP switches to enable the built-in EOL resistors and/or
biasing circuitry
Refer to the controller's Hardware Installation Guide for how to identify and set a controller's
built-in EOL terminations.
At 9600 baud, the maximum number of devices is reduced to 25 due to the
increased time it takes for token passing between devices.