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Cooper Bussmann 245U-E Wireless Ethernet Modem & Device Server User Manual
Rev Version 2.19
Figure 47 Modbus Mappings for Unit B
Unit C is configured with Modbus TCP server enabled and device ID set to 1, so that the Modbus TCP client at
unit B can connect and read the status of the onboard digital input. Unit C also has the Modbus TCP to RTU
gateway enabled (see “RS-232 / RS485 Modbus TCP/RTU Converter”) so that the Modbus TCP client at unit B can
communicate with the serial Modbus RTU device D.
Unit B is configured as shown above in Figure 47.
• The first mapping will write the register 4300 (local digital input) to server IP address 192.168.0.200 (Unit C),
device ID #1 and register 4320 (digital output).
• The second mapping shows a Modbus read command of 8 discretes, starting at register 1 (Destination Reg)
on device ID #6 connected to IP address 192.168.0.200, and storing the values locally at register #1(itself) .
• The third mapping shows the Modbus write command (write coils), which is writing the local 8 I/Os starting at
register 1 across to server IP address 192.168.0.123, device ID #5, destination reg #1.
Additional configuration parameters for unit B are shown in Figure 48. The Modbus TCP client has been enabled
with a 500 msec scan rate, indicating that there will be a 500-msec delay between each of the mappings directed
at any server. The “Reset Registers on Comms Fail” option is enabled with a timeout of 60 seconds, indicating that
any of the registers at unit B will be reset if a successful Modbus transaction involving that register has not been
executed in the last 60 seconds.
Since the 245U-E supports Modbus TCP client and server simultaneously, the Modbus TCP server for unit B above
could also be enabled. This would allow one (or more) external Modbus TCP clients anywhere on the extended
wired or wireless network to connect to unit B and monitor the status of the I/O registers, including the I/O at
units A, C, and D. This is a very powerful and flexible feature that could, for example, be exploited by a central
monitoring facility or SCADA.
Figure 48 TCP Client Configuration
Modbus TCP Configuration on I/O Transfer Menu
The following table describes the settings shown in Figure 48.