Paolo_911

Inconsistent MES-PLC connection

9 posts in this topic

In the MES log files it confirms my observations that we are losing communication from the PLC to the MES US module on a daily basis, even a few times daily. The Q03UDECPU communicates with the MES module through its CPU front port through a 116TX N-tron Ethernet switch. If anyone can help ensure consistent communication without dropping connection that would be appreciated. I'd also like to know if anyone would share PLC program ideas to make sure I have constant communication with the MES module. Should I just use a simple timer that waits for the MES module to toggle a bit, then fault out if the bit isn't toggled within a certain period of time? It feels too simple to be robust haha. Anyways, any ideas on this communication would be appreciated.   

 

I  should also note that I have an EIP4CCPU module in the same rack as the PLC that is connected to the same Ethernet switch looking at other Ethernet IP devices. I wouldn't think this would be causing traffic (due to fast RPI?) or issues in the Enet switch, but I figured it is worth mentioning in case anyone has any reason to believe this is an issue. 

Edited by Paolo_911

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Doesn't EthernetIP broadcast all messages? Or is that a different brand? I don't remember exactly but there is one provider who recommends physically (and I mean physically - NOT VLAN tagging) separating the networks due to broadcast messages...

Anyway: You say you loose connection between PLC and MES module, but the MES module is connected to the same rack as the PLC? Or are there two different racks?? If the same rack, you don't need to "communicate" between MES and PLC using Ethernet...

I'm not into the U.S. definitions of the MES module, does "MES US" mean the CCPU controller with DeviceWise software loaded, or is "MES US" the QJ71MES96 module?

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Maybe I'm not understanding your setup fully...

You have the  Q03UDECPU  and the MESIT module on the same rack but you're communicating over Ethernet instead of the back plane?

Also, according to Mitsubishi, the Ethernet port on any CPU is not intended for anything other than "Light" work.  If you are using the port for large data transfers/communication you might want to consider a dedicated Ethernet module.

I'm assuming that when you way that you're loosing the network that the MESIT module is faulting out?

If that is the case you may need to look into your scan times, and use some on demand triggers.

As for t/s networking connectivity, if you have a manageable switch (sorry, didn't look up your model) you can mirror the ports and put Wire shark on it.

Just some brainstorm ideas here, disregard if I didn't understand your questions fully.

 

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Thank you both for your reply, and I apologize for my delayed thanks.

The MES module is on a separate rack, and communicates through an Ethernet switch to the FRONT PORT of the PLC on another rack. I am not sure what you (kaare_t) meant by separating networks, but I believe EthernetIP is an Allen Bradley network protocol. As for your other question, when I say MES US I am referring to the QJ71MES96 module.

NeilBDSSA I was NOT aware the Mitsubishi recommends AGAINST using the front port for anything other than light work. I am in the process of purchasing an Ethernet module to place in the rack to see if that solves this issue, which by what you said it most likely will. I'm not sure if the MESIT module is faulting out. How can I tell if the module is faulting out? Currently we don't have anything monitoring the MESIT module in the way of programming or anything, which I'm sure is bad. We are new to the MES system and I had posed the question of how to monitor it through the PLC, but didn't get anywhere with it. Perhaps you could help in this regard as well so we can keep a close watch on its status and alarm/fault if need be. I don't believe the Ethernet switch is a managed switch though to answer your other question. The only way we knew we lost connection, was that we were having issues and looked at the MES log file. I'm not sure how my I.T. department who handles the MES programming got this log file though. It just stated that it lost connection with the PLC, basically. 

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In a nutshell, I'm going to try using the Ethernet module QJ71E71-100 instead of the front PLC port and let you know how that works out to resolve this poor connection between the MES and PLC. 

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Thanks for the update @Paolo_911.

Regarding separating the networks I simply meant that you should (I think) have two physically separated networks: 1 "special" for EthernetIP if you utilize their realtime stream, and 1 "general" network. You should have different cables and different switches and so on. The reason why I believe this is so is that EthernetIP can use multicast messaging between nodes which can cause very high network loads. To explain a bit more: Multicast messages is like yelling in a room, if you have 20 people yelling at the same time, no one can understand what anyone is yelling. Multicast is a node that generates network traffic that ALL ndoes receives (and processes to some extent). But I am NOT an Allen Bradley specialist, I'm only stating my limited experience with EthernetIP in a test network. I'm sure it depends on the configuration of the EthernetIP network/nodes. I'm just saying it can be a possible issue to look into if they share switches.

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The MES software is called workbench.  It should be downloaded from your software portal.

Not sure if you IT dept. will allow you to connect to view the logs maybe they can export them for you to view.

Again, with not fully understanding the setup - according to the course-ensure that you have a good switch (which I believe you said you did,  my main concern was a switch vs. a hub), a dedicated Ethernet module, which you said was on order.  

Some other points noted in the class will require you to check your scan times and triggers.  The MES module can overloaded when either reading/writing to a SQL database - which you will just basically loose data (maybe it appears as a connection issue).  You will likely need to spend time performance tuning.

I'm still learning myself, hope this helps you.

 

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@Paolo_911: You said you had the QJ71MES96. I believe that @NeilBDSSA is using the CCPU that is "modified" to a MES module by DeviceWise since he/she is referring to the Workbench. At least the software I used to configure the MES-IT (CCPU) is called "Workbench" while the software I used to configure the QJ71MES96 module is "just" a package from Mitsubishi. They are quite different modules, the QJ71MES96 is a module while the CCPU is basically a CPU with software. Please specify exactly which module you are using... I've attached two pictures, one of each unit. Tje QJ71MES96 has ONE network port, while the CCPU has two network ports. Please specify which one you have.

 

13950_400_300.jpg

download.jpg

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Thanks guys, I am using the QJ71MES96US module, not CCPU. My IT department did send me the log which is attached here and I do have access the MES Workbench. However, my I.T. department does all the programming in there as I am unfamiliar with it. They have discussed trigger times with me, but I'll discuss it with them again to look at the scan and trigger times if adding an Ethernet module doesn't solve the issue. Thank you for all your guys' help though!    

MES log.jpg

Edited by Paolo_911

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