When Modbus RTU is master, you need to tell this gateway what IP address is mapped to which RTU slave
address. If there is a one to one correlation between RTU slave address and Modbus TCP address, enter
them as illustrated below. Here we see RTU slave addresses 1 through 3 corresponding to three different
IP addresses.
The first and last slave address incoming in this example simple mean that RTU slave addresses "1
through 1" correspond to the first IP address on the list, and unit number 1 will be transmitted as unit or
slave ID in the TCP packet. The RTU slave addresses "2 through 2" mean RTU slave address 2 will
translate to the second IP address, but its unit number will be sent as 1. If all of the Modbus TCP devices
expect to see unit number (or slave address) of 1, this mapping is how we instruct the gateway to
translate the slave address. Often a Modbus TCP device will disregard the unit number and it doesn't care
what number you send.
3. Configuring Gateway as a Modbus RTU Master
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