Product Guide VESDA ECO Detector by Xtralis
16 Installation 17898_05
By default, the Modbus protocol settings for an RS485 interface are
• Baudrate 19200
• Parity Even
• Stop Bits 1
These are the default settings programmed into the ECO at shipping. Refer to the
ECO Configuration section on page 33 for details of how to program the address,
Baudrate etc.
The RS485 specification gives a maximum permitted cable length of 1200m. There
are two methods of terminating the Bus. The ECO detector can operate with either
method, but the user should ensure that any 3
rd
party devices attached to the bus
are compatible with that method of termination.
• Basic DC termination in which a 120Ω termination resistor should be
connected across the connections A & B at the two end points of the Cable,
i.e. at the RS485 Master interface device and at the last device on the bus.
The ECO detector is provided with a 120Ω termination resistor fitted to the
PCB assembly along with a jumper connection next to SKT2, which permits
the user to connect the 120Ω termination to the bus. The jumper is fitted
as supplied and should be removed from all units except for the last
one in the line.
• Biased Bus Termination. Using a biased bus, the user must use an AC
termination and Biasing resistors. Refer to the Modbus specification for
details.
The two methods of termination must not be mixed on the same bus.
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