This is undoubtedly a newer 5370 or 5380 CompactLogix controller.
For these CompactLogix controllers the Ethernet port is embedded with the processor and not defined as being on the CompactBus itself, as was the case for the older CompactLogix Ethernet controllers, such as the 1769-L32E and -L35E. This means that the Ethernet port is more readily exposed to external communications and that a simpler path may be defined i.e. less hops.
When defining a target path for one of these CompactLogix controllers, say in a PanelView 800 application, the IP address of the controller just gets you as far as the Ethernet port itself. But you must also hop to the backplane "1" and then to the controller, or processor, which is always slot "0". So the fully defined path must also include the backplane address "1" and the processor slot "0". This directs the external device's communications all the way to the processor.
Example:
192.165.1.10,1,0
192.165.1.10 = IP address of Ethernet port
1 = Backplane address
0 = Processor slot
If going back out the Ethernet port on these controllers you must append the Ethernet port address only to the beginning of the path. Because the Ethernet port is embedded with the processor, the processor does not need to hop to the backplane and then to the port. For this purpose, the Ethernet port is assigned a local address of "2" for the 5370 and 5380 CompactLogix controllers. So the Ethernet port's IP address is not required here. The "2" automatically implies the Ethernet port is the first hop.
Example:
2,192.165.1.10
2 = Ethernet port
192.165.1.10 = Target device IP address
For the 5380 CompactLogix controller, they also may utilize what is known a "Dual-IP mode". The dual Ethernet ports may be used as separate ports for both Enterprise and device-level communications. In this mode they may have unique IP addresses. So to define which port the outgoing communications are targeted for the ports are assigned the addresses...
Port A1: Enterprise port - 3, IP address
Port A2: Device-level port - 4, IP address
When configured for Linear/DLR mode the path is "2, IP address" as above.
I tried to be as quick and brief as "I" can be there, so forgive me if that's not clear enough?
Regards,
George