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Modbus tcp to rtu gateway – Weidmuller WI-MOD-945-E: 900Mhz Wireless Ethernet & Device Server v2.16 User Manual

Page 43

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Weidmuller Wireless Ethernet Modem & Device Server WI-MOD-945-E User Manual

Page 43

www.weidmuller.com

Rev 2.136

Modbus TCP to RTU Gateway

The Modbus TCP to RTU Gateway allows an Ethernet
Modbus/TCP Client (Master) to communicate with a serial
Modbus RTU Slave. The WI-MOD-945-E makes this possible by
internally performing the necessary protocol conversion. The
conversion is always performed by the WI-MOD-945-E which is
directly connected to the Modbus serial device (i.e. only this
module needs to have Modbus TCP to RTU Gateway 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 WI-MOD-945-E

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 serially by the WI-MOD-945-E within the configured Response Timeout, the WI-MOD-945-E will
initiate a number of retries specified by the configured Maximum Request Retries.

The Modbus TCP to RTU Gateway may be configured to operate on either the RS-232 or RS-485 port.