EasyIO FD-20i User Reference v1.2
RS485 Connection
RS485 connection must be terminated at both ends with termination resistor, typically 120 Ohms. It is
recommended to use shielded twisted pair wire (STP) for the wiring. Lightning protection circuit is
recommended to be installed at one end of the wiring. The controller should be wired in daisy chain
network topology as shown as image below. If wire branch can be avoided, keep it as short as possible,
and never connect more than one device to the wire branch.
Be careful if single power supply is used for all connected RS485 device, make sure all devices are
having the same ground connection. Make sure you are connecting the same wire for the same
terminal position, all “H” terminals connected to the same wire.
Daisy Chain Network Topology
RS485 Connection
RS 485 Serial port settings.
Every EasyIO FC controller comes with 1 physical RS -485 ports respectively.
However EasyIO provide 2 sets of RS-485 terminals for easy wiring terminations.
Below is a table showing the default details for serial port.
Port Number
Protocol Communications supported
Default Serial port settings
Remarks
Port 1
Modbus OR BACnet
Protocol selection is done via DIP switch 1.
DIP 1 = OFF = Modbus RTU
DIP 1 = ON = BACnet MSTP
Modbus
Baud Rate
: 19.2K
Parity
: even
Data Bit
: 8 (Not editable)
Stop Bit
: 1
BACnet
Baud Rate
: 19.2K
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