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Unread November 8th, 2016, 10:03 AM   #1
taylor1982
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UDP socket communication to PC with ControlLogix and 1756-EN2T

Hello,

I need to establish a UDP socket communication between a ControlLogix L72 PLC and a Linux-PC on the other side with a 1756-EN2T network card.

I have really no idea how to do this. I found nothing suitable in the AB library or knowledgebase.
Can anyone provide a sample program how to handle this?

Thank you so much in advance!

Stefan
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Unread November 8th, 2016, 11:46 AM   #2
jstolaruk
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Unread November 8th, 2016, 12:31 PM   #3
Contr_Conn
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Since your question is very generic, I can only recommend you to start with the Logix Sockets user manual enet-at002
http://literature.rockwellautomation...t002_-en-p.pdf
and technote 32962

there are plenty of examples in the knowledgebase
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Unread November 9th, 2016, 01:49 AM   #4
taylor1982
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Thanks for your replies.

Due to this I have a view questions:

- I need to implement a very fast connection so I need to send and receive as fast as possible. How ist the best way to trigger the READ and WRITE message instructions?
- Can READ and WRITE be triggered at the same time?
- How do you usually trigger the instructions? With a fast toggle bit and the negated .DN-Bit before the message instruction?

Thank you!
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Unread November 9th, 2016, 12:21 PM   #5
Ken Roach
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Quote:
- I need to implement a very fast connection
If so, use cyclic I/O instead of raw sockets and UDP.

The best way to do this is to buy a Linux EtherNet/IP Adapter software product, or try the open-source OpENer project:

https://github.com/EIPStackGroup/OpENer
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Unread November 10th, 2016, 01:34 PM   #6
taylor1982
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Quote:
Originally Posted by Ken Roach View Post
If so, use cyclic I/O instead of raw sockets and UDP.
Unfortunately this is no option. On the other side is a Linux PC and the customer want to use UDP sockets.

Any suggestions?
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Unread November 10th, 2016, 01:40 PM   #7
marshg
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Due to this I have a view questions:

- I need to implement a very fast connection so I need to send and receive as fast as possible. How ist the best way to trigger the READ and WRITE message instructions? I usually use an XIO |\| for the message enabled and then use a timer done bit XIC | | in series that pulses every 50msec or 100msec. The TON instruction would use an XIO |\| for the timer done in front of TON instruction. From my experience, only using the |\| Enable bit will cause the message instruction to hang sometimes. Make sure to use the done bit in series. Sorry, I don't use Rockwell at my current job so I hope the example shows up correct.
Msg.EN Tmr.Dn
|\|---------| |-----------MSG Instruction called Msg

Tmr.Dn
|\|-----------TON Instruction called Tmr

- Can READ and WRITE be triggered at the same time? Yes. The EN2T can hold up to 256 connections if I remember correctly. You can log into the EN2T card by typing in its IP address to see the maximum number of connections. You'll want to monitor this.
- How do you usually trigger the instructions? With a fast toggle bit and the negated .DN-Bit before the message instruction?

Thank you!
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Unread November 10th, 2016, 05:23 PM   #8
Contr_Conn
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Unfortunately answers in the post above are incorrect and misleadng
The rules above do not apply to sockets
You cant do socket read and write at the sametime
And performance really depends on the socket serice timeout as Msg reads the buffer and not the actual udp stream
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Unread November 10th, 2016, 06:06 PM   #9
Ken Roach
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Quote:
Unfortunately this is no option. On the other side is a Linux PC and the customer want to use UDP sockets.
Then change the customer's expectations.

ControlLogix cyclic I/O connections are fast, bi-directional, and use UDP. That sounds good to me.

You will almost certainly not get the performance you want from the raw sockets feature of the 1756 Ethernet modules.
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Unread November 19th, 2019, 11:29 AM   #10
BachPhi
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Quote:
Originally Posted by Ken Roach View Post
If so, use cyclic I/O instead of raw sockets and UDP.

The best way to do this is to buy a Linux EtherNet/IP Adapter software product, or try the open-source OpENer project:

https://github.com/EIPStackGroup/OpENer
Does RTA 490NBX count as a fast Linux EtherNet/IP Adapter?
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