User Manual

Communication
BACnet MSTP over RS485
6
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Code Description
01 Read coil status
02 Read input status
03 Read holding registers
04 Read input registers
05 Force single coil
06 Preset single register
15 Force multiple coils
16 Preset multiple registers
Cable guide
When selecting RS485 cables:
● Use 2-wire twisted pair cabled with shielding
● Select the right cable diameter to ensure maximum cable length. For example,
AWG24 at 9600 bps can reach 1,000 meters.
● Class 5 cable: The maximum length is 600 meters.
Limitation of Modbus RS485
● Master mode: see the Climatix limits document.
Baud rate
The following values are permitted: 600, 1200, 2400, 4800, 9600, 19200, 38400,
57600, 115200 (value must be 49664).
Note: The baud rate must be the same for all nodes on the bus!
6.2 BACnet MSTP over RS485
Features
The C400 controllers use the RS485 interface to support the BACnet MSTP
communications protocol to connect with BACnet MSTP clients and exchange
information with a monitoring system. B-ASC profile is supported.
● POL467/468 support MS/TP and BACnet IP, but only one protocol is supported
at one time. To enable the BACnet MSTP function, first disable the BACnet IP,
then switch on the BACnet over RS485 (see below):