Eos –Gate Installation and operation manual
All the information provided with this document are property of Carlo Gavazzi Controls SpA
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10.1.9 RS-485 limits
RS-485 limits
Description
Limits
Suggestions
Notes
Trunk cable length
Depends on cable, speed ,network
configuration and number of loads. For
example it is 1000 m for a 9600 bps, AWG26
connection
Derivation cable
length
Must be short, never more than 20 m
Maximum number of
RS-485 devices
without repeater
32 devices always authorized.
Depending on:
•
all the possible addresses,
•
the RS-485 unit load used by devices
•
the polarization
a larger number may be authorized
The use of a
repeater between
two heavy loaded
RS-485 MODBUS
is possible
The MODBUS device
manufacturer must
document the how
many devices are
authorized without
repeater
Maximum number of
devices addressable
by MODBUS on a
single Bus
One master and up to 247 slaves
10.1.10 Further information
Please refer to the following documents for further information:
•
“Modbus over serial line V1.02” specification
•
TIA/EIA-485-A standard specification