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Advanced Modbus Settings
Setting Value Notes
Enable (Default)
Auto Slave Unit ID
Disable
Select Enable when
multiple Modbus devices
are accessible at the same
IP address.
1
Character Timeout
10 to 3000 ms
(default = 100 ms)
This parameter is active
when the attached serial
device is set to
Modbus/RTU.
2
Message Timeout
10 to 3000 ms
(default = 1000 ms)
Allows you to configure
the message timeout for
communication between
connected Ethernet or
serial Modbus devices.
Modbus/TCP Exception
default = 502
This parameter is active
when the Modbus
Gateway connects a
Modbus/TCP Master with
Modbus serial slave
devices.
3
Additional Information
1.
Modbus/TCP protocol contains a “Unit ID” field to identify multiple Modbus
slave devices accessible at a single IP address. When the Modbus/TCP
command contains a Unit ID, the Modbus Gateway can pass the Unit ID to
Modbus serial devices. This allows you to link to multiple serial devices with
a Modbus Gateway. Some PLCs assume that each IP connects to only one
device. In these cases, the Unit ID can be set “0,” but you must manually
assign a Unit ID (between 1 and 247) to the connected serial device.
However, each Modbus Gateway can connect to only one serial device.
This setting is valid when [Attached Serial Device type] is set to [Modbus
RTU Slave ] or [Modbus ASCII Slave].
Enable: Uses the Unit ID in the Modbus/TCP packet. This is the default
setting.
Disable: Uses the predefined Unit ID instead of Modbus/TCP’s.
ID: The
p
redefined Unit ID value, ran
g
in
g
from 1 to 247, which is valid