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Brief
Descriptions of Modbus Features: |
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Modbus
TCP: This is the open
standard for sending Modbus messages over Ethernet using TCP/IP
packeting. Go to www.modbus.org
for details. |
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Modbus
UDP: This is variation
of Modbus/TCP where UDP is used instead of TCP/IP. UDP requires
less overhead than TCP/IP and thus is faster. UDP is ideal for
local networks where you want real-time performance. The
UDP Real-Time Ethernet Secret. |
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Modbus
ASCII: This is Modbus
protocol sent in ASCII format. This mode is ideal when sending
Modbus through radio or telephone links. However, it is slower
than Modbus RTU described below. |
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Modbus
RTU: This is Modbus
protocol sent in binary format using character-gap timing. This
mode is ideal for one-on-one RS232 or multi-drop RS485 connections.
It is not recommended for radio or telephone links because they
can interfere with the gap timing. |
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Master
Mode: This allows
the device to act as a Modbus master and to initiate Modbus messages
to a slave device. The data is then stored in internal registers
and can be accessed via another port. All SIXNET controllers and
RTUs allow each com port to be configured independently. Therefore,
one port can be a Modbus master and another a Modbus slave. |
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Slave
Mode: This allows
the device to only respond to Modbus messages that it gets from
a master device. In this mode the device will not initiate any
communications. |
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Passthru
Mode: This
allows Modbus data to be recieved on one port and automatically
sent out another. Typically it is used to transfer Modbus registers
from Ethernet to a serial device.
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