Ken Roach
Lifetime Supporting Member + Moderator
I really don't want to turn this into a 'basics of IP addressing' thread, because there are many thousands of books, websites, and classes that discuss that topic in detail.
But I'll try to clarify a couple of points.
Multicast I/O connections can only be established when the controller and the I/O adapter are on the same IP subnet. In simplified terms, this means that they both have a "192.168.1.x" address, or they both have a "10.1.1.x" address.
An I/O connection can be established using Unicast between a controller and an adapter on different IP subnets if there is a properly configured router connecting those subnets. The router will forward the packet to the remote network, and forward the reply. That's what routers do.
If another 1756-ENxT module is available and can be installed in the chassis with the ControlLogix and connected to the 10.1.1.x subnet, that is the simplest way to solve the original problem, because the controller and the adapter will be on the same IP subnet.
This doesn't mean it's the only way to solve the problem, or that it's the best way to solve the problem.
But I'll try to clarify a couple of points.
Multicast I/O connections can only be established when the controller and the I/O adapter are on the same IP subnet. In simplified terms, this means that they both have a "192.168.1.x" address, or they both have a "10.1.1.x" address.
An I/O connection can be established using Unicast between a controller and an adapter on different IP subnets if there is a properly configured router connecting those subnets. The router will forward the packet to the remote network, and forward the reply. That's what routers do.
If another 1756-ENxT module is available and can be installed in the chassis with the ControlLogix and connected to the 10.1.1.x subnet, that is the simplest way to solve the original problem, because the controller and the adapter will be on the same IP subnet.
This doesn't mean it's the only way to solve the problem, or that it's the best way to solve the problem.