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6193-5201
Multicast Group Port
Enter the UDP port number that all members of the
group will use (i.e. all group members should use the same
port number).
Multicast Group IP
Enter a valid Multicast IP Address identifying the group
(i.e. all group members should use the same Multicast
Group IP Address). Valid Multicast IP Addresses are in
the range 224.0.1.0 to 238.255.255.255.
3.13.3 Modbus TCP to RTU Server
The Modbus TCP to RTU Server allows an Ethernet Modbus/TCP Client (Master) to
communicate with a serial Modbus RTU Slave. The RM-240 makes this possible by inter-
nally performing the necessary protocol conversion. The conversion is always performed
by the RM-240 which is directly connected to the Modbus serial device (i.e. only this
module needs to have Modbus TCP to RTU Server enabled).
The above example demonstrates how a Modbus/TCP Client (Master) can connect to
one or more Modbus RTU (i.e serial) Slaves. In this example the RM-240 Access Point is
configured with the “RS232 Modbus/TCP to RTU Gateway” enabled. Once enabled, the
gateway converts the Modbus/TCP queries received from the Master into Modbus RTU
queries and forwards these over the RS232 port to the Slave. When the serial response
to the query arrives from the Slave, it is converted to a Modbus/TCP response and
forwarded via the network to the Modbus/TCP Master. If no response was received seri-
ally by the RM-240 within the configured Response Timeout, the RM-240 will initiate a
number of retries specified by the configured Maximum Request Retries.
The Modbus TCP to RTU Server may be configured to operate on either the RS 232 or
RS 485 port. It does not support operation on both ports at the same time.
Enable RS-232 Modbus TCP
to RTU Gateway
Check this box to enable the Modbus TCP to RTU
Server on the RS-232 port. Only a single serial port is
allowed at a time.
Enable RS-485 Modbus TCP
to RTU Gateway
Check this box to enable the Modbus TCP to RTU
Server on the RS-485 port. Only a single serial port is
allowed at a time.
Data Rate
The serial data rate desired. Serial data rates available
range from 110 bit/s to a maximum of 115.2 kbit/s.
Data Bits Parity Stop Bits
The data format desired. Data formats of 8N1, 7E1,
7O1, 7E2, 7O2 are supported.
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