Solution
There are two parts of IP address configurations, an RT controller side
(eth 0, eth 1) and an ethernet device side.
RT controller Ethernet Port Configuration
1. You can follow the link below.
2. Make sure that
IPv4 Addresses for both
eth 0 and
eth 1 are different from each other.
3. Make sure that
IPv4 Address for eth 1 is as
x.x.x.1For example, you can see the
IPv4 address is
10.0.18.1 as shown below.

Note: This picture is from
Figure 6. Configure Secondary NICEthernet Device Configuration
1. Make sure you have the same
subnet IP address as
IPv4 address of eth 1.
2. Make sure you have the same
subnet mask as the
subnet mask of eth 1.
3. Make sure you have the
gateway address as
IPv4 address of eth 1.
For example, you can configure an ethernet device as below to communicate with the RT controller on the picture above.
IPv4 Address : 10.0.18.20 (10.0.18.x can be used except "1")
Subnet Mask : 255.255.255.0Gateway : 10.0.18.1