ControlLogix Redundancy, Can I sue ENBT instead of EN2TR proposed by AB?

Hi Technocrats,

I've the below basic Controllogix Redundancy Configuration, could you please confirm if it will work. Have dual redundant network, hence CPU Rack-A & B have 2 ENBT modules to connect to both networks.

CPU Rack-A & CPU Rack-B (4-Slots Rack)

Slot-0: 1756-L71
Slot-1: 1756-RM
Slot-2: 1756-ENBT (Is this ok or will need to use the EN2TR?)
Slot-3: 1756-ENBT (Is this ok or will need to use the EN2TR?)

IO-Rack-A & IO Rack-B

Slot-0: 1756-ENBT (Is this ok or will need to use the EN2TR?)
Slot-1: 1756-IB32
Slot-2: 1756-IB32
Slot-3: 1756-OB32
Slot-4: 1756-OB32
Slot-5: 1756-IF8
Slot-6: 1756-OF4
Slot-7: MVI56-MNETR
Slot-8: MVI56-MNETR

Thanks in Advance

Quick answer - NO!

Basically, there wouldn't be problem if you use it on the remote IO chassis, but you will lose the second ethernet channel(or maybe it will be ring, that is proposed). The redundancy manual says you can use only enhanced communication modules (the ones that have "2"). I am not sure if you should expect loss of communication during switchover of the redundant processors, due to IP address swapping, the manual says, that you have to use certain FW revisions on the communication modules, so you don't get loss of communication with the IOs during switchover.

Hi mdim,

Thanks for the reply...

Yeah, I've just read it in the manual:

"....You must use enhanced communication modules in redundancy systems. Enhanced communication modules contain a ‘2’ in their catalog number. For example, the 1756-EN2T module..."

But nothing is mentioned about using ENBT in the remote IO Rack? If I use 1756-EN2T (Forget about EN2TR) for my CPU racks and ENBT for my IO Racks, are you sure it will work?

You can use the 1756-ENBT only in the remote I/O "adapter" chassis with ControlLogix Redundancy v19 and v20 systems.

I do not recommend it unless you already have an installed base of 1756-ENBT modules and existing spare parts. The 1756-ENBT is a mature module and will eventually be retired in favor of the 1756-EN2T; Rockwell Automation actually scheduled the end of production for December 2016 at one point, but then canceled that plan.

The cost difference is about 14% between these modules, but the 1756-EN2T has better performance and you would only need to stock one type of module as a spare.

Page 30 of the ControlLogix Enhanced Redundancy System User Manual (1756-UM535) has this to say about EtherNet/IP modules in remote chassis:

A remote chassis can be accessed over an EtherNet/IP network by using any
EtherNet/IP module that works in a nonredundant chassis with no
additional firmware requirement with the following exception. If the remote
chassis contains a controller that consumes a tag that is produced in the RCP,
it can only consume the tag with the required firmware revisions.

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