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beatopc

compactlogix 5380 Understand service data

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I have 0x4c requests from my ipc to the controller, with request path: Class - 0xB2, Instance - 0x004C.

And 0x4c responses from the same path, and then "Command Specific Data":

example 1 (of the command specific data):

0100a6409d00a6409d00a6409d00a6409d00a6409d00a6409d00a6409d00a6409d00a6409d00a6409d00a6409d00a6409d00a6409d00a6409d00a6409d00

example 2:

0100a7409d00a7409d00a7409d00a7409d00a7409d00a7409d00a7409d00a7409d00a7409d00a7409d00a7409d00a7409d00a7409d00a7409d00a7409d00

example 3:

0100a8409d00a8409d00a8409d00a8409d00a8409d00a8409d00a8409d00a8409d00a8409d00a8409d00a8409d00a8409d00a8409d00a8409d00a8409d00

Looks like it always starts with 0100, then repeating some value. In the first one the repeating value is 00a6409d, and then in the end 00. Or maybe it's 01 and then just repeating values surrounded with 00 or something similar.

Is it values surrounded with 00, written using little-endian?

Does the variable in request have a name?

 

Edited by beatopc

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This would be a lot easier to look at in wireshark.  Can you post a capture file?

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Hmmm.  Not what I expected at all.  Rockwell uses Service 0x4c differently on each class I've dealt with, and class 0xb2 is not one of them.  For example, on class 0x6c, that service reads a template definition (UDT or module-defined types).  In that form, it takes 6 bytes of additional payload in the request and delivers a complicated but documented reply. (Rockwell's Logic Data Access manual, publicly available.)

 

What model processor is this?

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I found a reference that hints that class 0xb2 manages (?) the processor's trend objects.

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This is compact logix 5380.

I'm not sure what trend objects are exactly, but I'll try to check.

Is there a documentation that tells how to read that data so I know I interpret it correctly?

Thanks!

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No documentation.  Private Rockwell object.  Trends are data logging elements within a Logix processor that can run at PLC speed, then deliver the results to slower devices.

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This is how we use it.

Thanks for the help!

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