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dmroeder / pylogix

Read/Write data from Allen Bradley Compact/Control Logix PLC's
Apache License 2.0
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Accessing I/O tags #179

Closed ShaliniBanerjee closed 3 years ago

ShaliniBanerjee commented 3 years ago

I have used Studio 5000 to program Logix 5571. I have used pylogix to read and write I/O tags. While using Wireshark to dissect the packets, though I could see the services 0x4c and 0x4d, I could not find the class that is being accessed. I have to perform some filtering based on class and I am guessing that the Symbol Class is being accessed. Could you please give me some insight into this.

dmroeder commented 3 years ago

I'd prefer emailing me or joining the discord for asking questions, rather than open issues.

Those services are Rockwell specific and largely undocumented. This is the only documentation I have ever found:

https://literature.rockwellautomation.com/idc/groups/literature/documents/pm/1756-pm020_-en-p.pdf

ShaliniBanerjee commented 3 years ago

Sure. Thank you.

dmroeder commented 3 years ago

Let me know if that document helps at all

ShaliniBanerjee commented 3 years ago

Could I get your email id please

dmroeder commented 3 years ago

Oh sure, it is in the setup.py file dmroeder@gmail.com

I don't know any more than what was implemented in pylogix, which largely came from that document. It has been a few years since I've had to pay attention to that portion of the protocol, I spent a lot of time in wireshark, scratching my head.

The reason that wireshark doesn't give you more details is because their CIP dissector only know what has been documented and these objects are not part of the CIP spec, they are "vendor specific" objects, at least that is how I understand it.