Distech ECYPSE - Page 114

BACnet MS/TP Communication Data Bus Fundamentals
114 ECLYPSE User Guide
At 9600 baud, the maximum number of devices is reduced to 25 due to the
increased time it takes for token passing between devices.
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 ECY Series Controller (if equipped) and one other
controller to 38 400 baud. If the ECY Series Controller becomes unavailable and there is
a power cycle, the ECB 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.
ECY Series
NET- NET + S
Typical BACnet Device
NET+ NET-
Typical BACnet Device
NET+ NET-
Typical BACnet Device
NET+ NET-
Typical BACnet Device
NET+ NET-
EOL ON
EOL OFF
EOL OFF
EOL OFF
Data Bus: Shielded Twisted Pair Cable
Electrical
System
Ground
Baud: Auto (Factory Default) Baud: Auto (Factory Default) Baud: Auto (Factory Default) Baud: 38 400 Baud: 38 400
EOL
ON
Figure 11-1: Setting the Baud rate on two Controllers on a BACnet MS/TP Data
Bus Segment for Failover Protection
To set the baud rate for:
 ECY Series Controllers, see Web Configuration Interface on page 70.
 ECB Series controllers, see the controller’s hardware installation guide or the Network
Guide.