Redundant ControlLogix to Remote Stahl IO Base over EthernetIP

[alexpinna]

I have a Redundant ControlLogix L61 System running on firmware 16.52.
There is an existing ControlNet network for the ControlLogix IO bases but we are expanding the plant and have added a Stahl Remote IO base as we have done in many other parts of the site. The difference here is this is our only plant with redundant PLCs.
When I try to add the Generic Ethernet devices to the Ethernet network to configure the communications to the Stahl IO and download I get the error code 16#000C - Service Request Error. Invalid mode of state for service request. I have tired may different options but I think it might be due to the redundancy as this is a tried and tested setup I am using. Each PLC rack contains a 1756-L61, a 1756-CN2R, a 1756-EN2T (which is the network I am trying to add the remote IO to) and a 1756-RM2.
Does anyone have any experience of this or a solution?

 

[harryting]

Is the EN2T existing or a new addition? Be sure the IP address of the 2nd EN2T is set to the same as primary.

Also, is the firmware of the EN2T 4.002 or above?

 

[alexpinna]

The two EN2Ts are existing. They are used to communicate with the SCADA system.
Yes the IP addresses are set the same, the redundancy system is all existing hence why it is on such an old revision, I wanted to upgrade as part of this project but was unable to at this time.
The EN2T firmware is set to 2.7, I believe it must be this for the redundancy kit compatibility?

 

[Ken Roach]

The 1756-EN2T modules are probably Series A, B, or C, so they'll probably have to stay with version 2.7 firmware.

This was about the time that the -EN2T Series D was released (along with Redundancy firmware 16.81 or so) that supported v10 signed firmware. You will find warnings not to attempt to put old firmware on a /D or later module, or put newer firmware (higher than 2.7) on a /C or older module.

I'm not totally sure the EN2T is going to be supported by 16.05x firmware. I have found references to it in the 16.081 Kit 5 release notes, but the older 16.057 Kit 1 refers to them only in passing.

In fact, I see references to 16.050, 16.053, 16.056 and 16.057, but not 16.052. Those numbers were "bundles" of firmware all designed and tested to work together, nominally identified by the 1756-L6x controller firmware revision.

I'm not sure where the "kit" numbers came from. I'd have to compare them.

 

[Ken Roach]

Also: Alex, welcome to the PLCTalk forum community !

Are you using these 1756-EN2T's solely to connect with those Stahl Remote I/O bases, or do they also have an HMI or RSLogix 5000 connection function ?

 

[alexpinna]

They also communicate with a scada system and rslogix.

 

[Contr_Conn]

The lowest version of redundancy that supports Ethernet I/O is 19.
Version 16 does not support Ethernet I/O

 

[Ken Roach]

Thanks for confirming that.

I have some v16 Redundancy systems operating but we built them with ControlNet for media redundancy so I only have my eight-years-past recollection about what was available for Ethernet. On those systems, our ENBT is in a remote chassis to provide HMI/ERP access to the machine.

Alex, don't be tempted to try to put a 1756-ENBT or -EN2T in a remote ControlNet chassis and use that to establish I/O connections. RSLogix v16 won't prevent you from doing it, and it will appear to work at first, but the connections will drop unexpectedly when the system reallocates buffers during ordinary HMI work.

I think you're going to need an upgrade to a v19 firmware bundle to accomplish this.

 

[Contr_Conn]

Bridging ControlNet to Ethernet for I/O is not supported even in higher versions. In fact it's not supported in any version of non-redundant controllers as well.
Search knowledgebase for the technote called "Unsupported Bridged I/O Configurations"

To do I/O in V19 or V20 or even higher, you must have EN2T modules in the controller chassis. You will have to replace CNB modules with CN2 modules because you can't mix CNB and EN2T in the same redundancy system.

 

[Ken Roach]

I should have been clearer: outside-the-CPU-chassis "root bridge" modules aren't supported in ANY version, but I thought that later RSLogix/Studio 5000 versions at least warned you.

I was involved in a big headache with a customer who tried that architecture, and made a mess of their cogeneration plant, and I was left sputtering "why did you think that was even possible ? That's not how those work !", with the answer being "because RSLogix let us configure it that way".

 

[alexpinna]

I wasn't bridging, the Ethernet connection was via the en2t on the controller rack. I have found the issue is Ethernet Io is not supported in redundant PLC's prior to version 19. Thanks for the help.