ControlLogix ENBT Problems

I have a current system using a CLX processor with local IO modules and and local ENBT module that communicates with 4 Flex IO nodes. I am having some weird things happen in that the ENBT module stops working after some time. The message that I get is Code 16#0204 Connection Request Error: Connection request timed out.

The only solution to this is to either reseat the module or cycle power to the PLC.

I am trying to understand if the message is between the processor and module or if it is something on actual network itself.

I calcualted the Packets Per Second limit on the module and I am okay there. I don't have much room for expansion but that shouldn't matter because it will never change. I also monitored the connections on the processor and that is well below the limit.

I guess I am trying to see if the problem has to do with the network or something in the module that the CPU can't connect to it.

I have attached images of my IO tree with error message.

Any thoughts or suggestions would be appreciated. Thanks in advance.

Where these modules recently added?

No. The system has been in place for about a year. This problem seems to be happening more often. It always seems to happen when the machine has been sitting idle for some time. It has never happened while the machine is running (making parts).

I am trying to understand what to troublshoot. The module in the backplane or the Ethernet network itself.

Might it be the physical networks cables connection issue?

Since the connection to the 1756-ENBT itself is broken, that puts that module under suspicion. If it were a network problem, only the remote devices would have timeouts.

You should visually inspect the module for the 2007 "Atmel 64" issue. Check out the RA Knowledgebase for details.

Ken,

Thanks for the feedback. You confirmed what I thought. The connection between the CPU and module has been broken. I was trying to confirm this based on the error code.

I will check out the KB. Thanks.

Just a thought (and question, really) - in your second picture, the RPI is set for 0ms. Is this good? Shouldn't it have at least some value (2-100)?

Steve

There is no true RPI between the CPU and the module in the rack. The setting is actually grayed out. The RPI is between the module and the producing/consuming modules on the network.

I'm a little new to the ControlLogix stuff, but I'm not so sure there is no RPI for your module. When I insert a new 1756-ENBT/A module in my application, it allows me the option of setting the RPI. Later, after it has been downloaded to the processor, I agree - you can't change it. The only way I have found to make that change it after that is to replace it in the tree.

Steve

In the application of cosumed/produced tags using EthernetIP, the connection is really between the processor and the nodes on the network. The ENBT module in the rack is just a bridge to get out to them. The module by itself does not have a scheduled (implicit connection) to set. It is actually grayed out while offline.

That is my understanding anyways. I am sure someone else can clarify this.

Ok. I'm with you now.

I created a new application for a L63 processor and then setup a 1756-ENBT/A module in the first slot. Like you say, the RPI setting is 0 and is greyed out right from the start.

Good luck.

Steve

Did you ever get any resolve on this.....?? I have been chasing the EXACT same issue with an ENBT in a CLOGIX backplane. I have even written a routine that inhibits the module when it gets the 516 communication error, then un-inhibits 5 secs later. This traps the error message for me, but won't bring the module back to life. Power cycling the rack is the only solution, so I actually added a relay into the mix and cycle power after 45 seconds if the module stays in the comm fault.

I have been chasing this phantom for a year now. So far I have replaced the ENBT, the N-Tron Switch and the 13 Slot rack....nothing cures this.

I am ALL EARS if someone has the solution. I have also exhausted all of Rockwells solutions such as removing Rack Optimization etc...