Emerson Exchange 365

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What is the best way to connect EtherNet/IP on different networks.?

Currently we are working on a project with EtherNet/IP communication among a handful of devices.  There is a skid package that uses CompactLogix to control all the drives and I/Os within that package.  All of the devices, including the PLC is on its own 172.28.0.xxx network.  Our client's requirement for our EtherNet/IP network is on 192.168.1.xxx network.  Which solution is better? 

1) By using a router to map 192.168.1.xxx gateway to 172.28.0.xxx OR

2) Ask our client to provide a list of available addresses on the 192.168.1.xxx network to change all IPs on the devices on the skid package? 

I still don't quite understand how the gateway method works.  If someone as a better understanding of the using EtherNet/IP across different networks, please indulge me. Thanks in advance!

JackC

• 2 Jul 2018 5:10 PM
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2 Replies

• Tim Fedorov

  

  • 2 Jul 2018 6:17 PM

  Hi JackC.
  
  (2) Is probably the "best" approach in the near-term and longer-term, but will take some additional elbow grease up front depending on how many IP's you need to reconfigure and across how many distinct devices (and how easy that configuration change gets pushed out).
  
  (1) is actually very straight forward using a 1-to-1 NAT (en.wikipedia.org/.../Network_address_translation), provided your router allows you to configure a NAT mapping. However, it can introduce many headaches down the road, particularly to the long-term support-ability of the skid; NAT also does not play well with certain QOS and IPv6 functions.

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• Gsr13k

  

  • 2 Jul 2018 7:41 PM

  Jack,
  
  The issue that you may run into with (2) is that if you are an OEM and have to support your client, you will have to keep up with a different set of IP addresses. As your client base increase so will the number of IP to maintain. If that doesn't matter then re addressing your equipment is the way to go.
  
  That being said, doing a NAT translation works well with not having to change any addresses and also adds a boundary to mitigate unwanted traffics. In addition, if you had multiple skids, utilizing NAT will allow you to keep the IP identical.
  
  Basically you are defining a table that maps the "private addresses" the (172 class B), and giving them the "public addresses" (192 class C).
  
  Hope this helps.

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