Communicate Ethernet/IP from PC through gateway

[Mattyb199]

Hello y'all!

So I am a poor software engineer that got assigned a project to try and simulate a plc to test barcode scanners.

Basically my application needs to be able to use most industrial protocols and the plan was to try and implement Ethernet/IP functionality into the application and use gateways (E/IP->x) to achieve Profinet, Profibus, etc.

The plan sounds great but i ran into trouble actually being able to use the gateway. Obviously most gateways are made to be used with a PLC application to handle messaging. My question is does anyone have experience trying to send messages through a gateway from a PC? I cant seem to find any examples of this being done before.

We are using a Softing Ethernet/IP to Profinet gateway to communicate with a Cognex barcode scanner. We are using python libraries (we are trying both pycomm and cpppo) to create the Ethernet/IP connection from the PC.

Any help or guidance would be appreciated!
Thanks

 

[lfe]

Rockwell uses at least 3 different protocols called Ethernet/IP:

1-Ethernet/IP Scanner/Adapter which is the one used by Control/CompactLogix to communicate at the field level with remote I/O.

2-Ethernet/IP Master/Slave for CLX at the Scada/HMI supervisiory level

3-Ethernet/IP at supervisiory level for SLC and Micrologix PLCs

I think that python library would probably correspond to protocol 2 or maybe 3, but instead to communicate with a barcode scanner you would need protocol 1.
There is also the problem that the specifications about Ethernet/IP are not free, it is only available to members of the ODVA association.

 

[Mattyb199]

Rockwell uses at least 3 different protocols called Ethernet/IP:

1-Ethernet/IP Scanner/Adapter which is the one used by Control/CompactLogix to communicate at the field level with remote I/O.

2-Ethernet/IP Master/Slave for CLX at the Scada/HMI supervisiory level

3-Ethernet/IP at supervisiory level for SLC and Micrologix PLCs

I think that python library would probably correspond to protocol 2 or maybe 3, but instead to communicate with a barcode scanner you would need protocol 1.
There is also the problem that the specifications about Ethernet/IP are not free, it is only available to members of the ODVA association.

I was not even aware there were that many different forms of Ethernet/IP! You did say that i would most likely need the first one you mentioned. The one library we are trying to use specifically names Control/CompactLogix, but we are still not able to connect to it. In the documentation it says that the library only works for "unconnected" type connections. Could the issue we are facing come from the fact that this is a connected connection type?

*From the library documentation*

"Only EtherNet/IP “Unconnected” type connections are supported. These are (somewhat anomalously) a persistent TCP/IP connection from a client to a single EtherNet/IP device (such as a *Logix Controller), which allow the client to issue a sequence of CIP service requests (commands) to be sent to arbitrary CIP objects resident on the target device. Cpppo does not implement “Connected” requests (eg. those typically used between *Logix PLCs, in an industrial LAN environment)."

https://github.com/pjkundert/cpppo

 

[lfe]

To complicate further, at least in protocol 2 and 3 there are 2 types of messaging: connected and unconnected.

My Android HMI app uses connected for CLX and unconnected for SLC

The protocol 1 uses UDP packets and not TCP. It does not work in request/response mode but in publish/subscribe mode and I never found any related example code.

 

[shubhupatil]

Thanks for sharing.......