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Prosoft AN-X4 to Mettler Toledo IND570 Communication Problems

asked 2024-01-10 18:24:04 +0000

lea32d gravatar image

updated 2024-01-11 15:06:51 +0000

I have a customer that has a Mettler Toledo IND570 weigh scale controller that talks ethernet/IP to a Prosoft AN-X4 which converts to Allen-Bradley Remote I/O (RIO). The communications between the two devices work fine most of the time, but every 5-10 minutes or so the communications will drop entirely but will then re-establish in a matter of seconds. I have been in contact with Prosoft and have sent all of the AN-X4 logs them from which they determined that the problem is likely originating from the Mettler Toledo IND570. I ran wireshark on the line which did capture several TCP related erros but I am having difficulty interpreting them; would someone be able to help me understand what these errors mean? Unfortunately, I am unable to attach the wireshark file, so I have linked it to a google drive download. A couple of important notes:

  • These are the only two devices on the network
  • IP Address of the Prosoft AN-X4 is:
  • IP Address of the MT IND570 is:


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Can you make publicly available?

Bob Jones gravatar imageBob Jones ( 2024-01-10 19:54:59 +0000 )edit

Apologies, I believe it is available now.

lea32d gravatar imagelea32d ( 2024-01-10 20:18:37 +0000 )edit

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answered 2024-01-11 11:46:00 +0000

Bob Jones gravatar image
 that the problem is likely originating from the Mettler Toledo IND570

Funny how the one vendor blames the other as if that wasn't predictable, whether true or not! In this case I think they are right based on the packet capture. Some straightforward correlation: when the TCP connection for the EIP protocol Forward Open gets closed (via TCP Reset), the MT device stops producing Class1 implicit messages; this is the likely disconnect described. Recovery happens automatically.

image description

I have seen this before from a different vendor, but it has been a long time and the specifications could have changed. That being said, it used to be that there was no requirement in the spec that the TCP connection has to remain open for implicit messaging to continue - recall for EIP, some CIP messaging via TCP is used to setup the implicit (class1 cyclic) communication stream. I don't know why Prosoft is shutting down the TCP connection, but I would argue that per specification, it shouldn't matter and implicit communications should continue until the implicit connection is shutdown at application layer.

The ODVA specs are not free so I cannot check to see if behavior in this area has changed.

Aside: Packets are out-of-order in the pcap file. I would revisit your capture strategy to avoid this - it does not have any bearing on this issue as it is easy to spot and workaround, but could matter in the future.

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Thank you for the answer!! I realized this morning that I had the IP addresses flipped (I've updated them in the post). Sorry about that. So, just to clarify can you verify which IP address is actively closing the TCP connection? Again, thank you for the response.

lea32d gravatar imagelea32d ( 2024-01-11 14:10:51 +0000 )edit

Look at the source IP in the screenshot - it is as the sender of the TCP reset to close the connection.

Bob Jones gravatar imageBob Jones ( 2024-01-11 18:24:18 +0000 )edit

Bob, thank you for the response - I had assumed that was the case but I wanted to have someone else confirm that as well. This was the first time I had ever used WireShark and I am pretty new the industry/networking; so, thank you again!

lea32d gravatar imagelea32d ( 2024-01-12 20:56:27 +0000 )edit

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Asked: 2024-01-10 18:24:04 +0000

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Last updated: Jan 11