Modbus
Cellular
Gateway
Index
skipping
is
used
to
reserve
slots
for
new
function
insertion,
when
required.
334
5.d.5
Modbus
Modbus
is
one
of
the
most
popular
automation
protocols
in
the
world,
supporting
traditional
RS
‐
232/422/485
devices
and
recently
developed
Ethernet
devices.
Many
industrial
devices,
such
as
PLCs,
DCSs,
HMIs,
instruments,
and
meters,
use
Modbus
as
the
communication
standard.
It
is
used
to
establish
master
‐
slave/client
‐
server
communication
between
intelligent
devices.
However,
the
Ethernet
‐
based
Modbus
protocol
is
so
different
from
the
original
serial
‐
based
protocols.
In
order
to
integrate
Modbus
networks,
the
IoT
Gateway,
including
a
serial
port
that
support
RS
‐
232
and
RS
‐
485
communication
interface,
can
automatically
and
intelligently
translate
between
Modbus
TCP
(Ethernet)
and
Modbus
ASCII/RTU
(serial)
protocols,
allowing
Ethernet
‐
based
PLCs
to
control
instruments
over
RS
‐
485
without
additional
programming
effort.
There
are
some
major
features
in
the
IoT
Gateway.
Dual
roles
of
Modbus
Gateway
and
Modbus
Slave.
Integration
of
Modbus
TCP
and
Modbus
RTU/ASCII
networks.
Software
‐
selectable
RS
‐
232/485
communication.
High
speed
serial
interface
supporting
460.8
Kbps.
NOTE:
All
devices
that
are
connected
to
a
single
serial
port
must
use
the
same
protocol
(i.e.,
either
Modbus
RTU
or
Modbus
ASCII).
