Add accessory/helper function to discover Logix PLCs about libplctag HOT 8 OPEN

Also an interesting idea. I think this can be done via a UDP broadcast IIRC. It seems like it would be interesting to combine this with the previous request.

The more I think about this, I am not sure I want it as part of the library, but it should be in related tools. It is difficult to make functionality like this generic for multiple kinds of PLCs.

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I would say it would be generic enough if you tried to find A-B PLCs and then pinged (Modbus TCP function code 3) every IP in the current subnet with both standard Modbus TCP ports (502, 1502). As I recall, you wanted to add Modbus, right?

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Still have not done this. I need the whole new structure of the library working to handle UDP as easily. It might be something I can do with each type of protocol. I have a structure now that will let me separate that out for the types of protocols that can support it. There might need to be some user input to get this information.

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Hi,

Is there some plan to do that ?
This library cannot be used to work with real PLC programs if it's not possible to get the tag list, or at least an identifier for an already existing tag...

Thanks in advance for your answer!

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@Folcogh In my case, my program reads/writes to a PLC whose program we wrote, so we know tag names ahead of time. I have used this library in production for years now, no issues.

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Thank you very much for the feedback. I finally understand the API. Really good lib, I could connect and do some things I needed to do.
But I definitely need to be able to discover all tags to fulfill my needs.

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There is an example of how to discover tags in an Allen-Bradley CIP-based PLC (Control Logix, Compact Logix). The example program is list_tags.c in the examples.

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