The concept behind routing is to provide a means of communicating with a remote ControlLogix backplane over various networks. Routing can be thought of as a bridge between your local ControlLogix backplane and a remote ControlLogix backplane even if they are on two different fieldbus networks. Access to a remote (destination) backplane allows for direct communication with the following modules located on this backplane:

Remote Modules Accessible Via Routing:

• ControlLogix 5000 processor for ControlLogix applications
• 1756-DHRIO interface module for DH+ Gateway applications
• 1756-CNB or 1756-CNBR interface module for ControlNet Gateway applications

A routing path is a series of backplane hops, with the last hop pointing to the destination backplane. Each hop requires a ControlLogix backplane (not a ControlLogix processor). An individual hop can utilize one of the following networks as its medium:

Networks Supported:

• ControlNet
• DH+
• Ethernet (EtherNet/IP)

Application Notes
1) Messages cannot be routed in or out of the same interface module channel more than once within the path. Doing so results in CIP Error 0x01 Ext. Error 0x100B.

2) For multiple channel interface modules, messages cannot be routed into and then immediately out of that same module (using different channels), regardless if the message is directed to the backplane first or avoids the backplane all together. As previously mentioned, the latter is not supported since each hop requires a ControlLogix backplane. An example would be to route a DH+ message from one DH+ link (ie. Channel A of 1756-DHRIO) to another DH+ link (ie. Channel B of same 1756-DHRIO) through one 1756-DHRIO interface module This is commonly referred to as Remote DH+ messaging and is not supported.

Connection Path Specification
The routing path is specified in the Device ID. As with non-routing applications, communication originates from the ControlLogix Ethernet driver on the PC and is directed at the local ControlLogix Ethernet Interface (1756-ENET). Once at this local 1756-ENET, the Device ID specifies a way out of the module and onto the backplane, just like with non-routing applications. From there the routing path will direct the message to the desired ControlLogix backplane. The remainder of the Device ID will determine what device to communicate with (ControlLogix processor, DH+ node, ControlNet node). The routing path specification begins and ends with the left and right bracket respectively ([, ]). The path itself is a series of port/link address pairs, identical to the Communication Path syntax in RSLogix 5000 Message Configuration dialog. A port describes a way out of a device via a network or backplane. A link address is a destination address and is commonly referred to as a node id or next hop.

The general syntax for the connection path is shown in bold below.

Single Hop
IP Address,Port ID0, [Link Address0, Port ID1, Link Address1, Port ID2], Link Address2

Multi-Hop (N Hops)
IP Address,Port ID0, [Link Address0, Port ID1, Link Address1, Port ID2, Link Address2, ... Port ID(N+1), Link Address(N+1), Port ID(N+2)], Link Address(N+2)

Note: The last Port ID in the path (Port ID2 and Port ID(N+2) for single hop and multi-hop respectively) must be 1 (port for backplane).

The Port ID0 must be 1 (port for backplane), Link Address2 and Link Address(N+2) are the slot numbers of the remote Logix processor/1756-DHRIO module/1756-CNB module.

Ports

Examples
Due to the complex nature of this feature, examples may be the best tutorial. The examples below will include the entire the Device ID minus the IP of the local 1756-ENET. Again, the perspective of the Device ID/Routing Path is from the local 1756-ENET module. Hop descriptions are in the form: Link Address(N), Port ID(N+1), Link Address(N+1), Port ID(N+2). See Connection Path Specification above for help. For further details on building a connection/routing path, refer to Allen-Bradley Publication 1756-6.5.14, pp. 4-5 through 4-8.

Key:
   Green = Ethernet
   Blue = DH+
   Orange = ControlNet

Example 1) Logix5550 to PLC-5 via DH+ Gateway

Example 2) Logix5550 to PLC-5C via CN Gateway.

Example 3) Logix5550 to Logix5550 via Routing over DH+.

Routing Path Breakdown

Example 4) Logix5550 to PLC-5C via CN Gateway, Routing over DH+.

Routing Path Breakdown

Example 5) Logix5550 to Logix5550 via Routing over DH+, ControlNet.

Routing Path Breakdown

Example 6) Logix5550 to SLC 5/04 via Routing over DH+, ControlNet.

Routing Path Breakdown

Example 7) Logix5550 to Logix5550 via Routing over DH+, ControlNet, Ethernet.

Routing Path Breakdown