ControlLogix Message Instruction Path

To write a message instruction (MSG) in ControlLogix one needs to give it a path to define where it needs to go. Following is how to set that communication path.

The path looks something like this:

What do the numbers mean? Pay attention that the numbers below don’t necessary correspond to the position in the address.

• Back plane = #1

• Ethernet/IP port, ControlNet port, DF1 (serial, serial channel 0), DH+ channel A= #2

• DH+  channel B, DeviceNet subnet, CompactLogix = #3

In the beginning we assume the message (intended to be sent over) is in a module in slot in the chassis. In order for the message to leave the chassis, it has to go through the back plane (annotated as #1) and then to the communication module. In our example above our communication module is an Ethernet module and is in slot # 6.

Then we need to define what media the message will travel through. Our slot #6 in above example is an Ethernet module, so that is how the message will travel through the network. The number corresponding to an Ethernet media is “2″. Hence the third number in the above address is 2.

The fourth number above is the IP address of the destination device. If we were to travel through ControlNet media, we would have a node number instead of the IP address in this position.

Once we go to the noted IP address, we are at the Ethernet module of the destination device. At this time to send the data to the intended processor the message needs to go through the back plane again. This is the back plane of the destination chassis. Back plane is specified by # “1″, hence the number “1″ after the IP address.

Once in the backplane of the destination, the message can go to the processor. It does however need to know which slot number the processor is at. The slot number of the processor in our example is “0″.

Two more examples:

Coming soon.

Related posts:

1. ControlLogix Messaging – RSLogix MSG Instruction
2. Electronic Keying Mismatch in RSLogix
3. AFTEK Develops Touch Screen HMI Platform