User manual

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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

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.