Reading and Writing I/O tags

sban346

Member
Join Date
Jul 2021
Location
Auckland
Posts
3
I am reading and writing to I/O tags in Logix5571 using python. While dissecting using Wireshark, I could see that the Symbol Class(0x6b) is being accessed with Service Codes 0x4c and 0x4d. I am confused about the following:

1. Is this the convention in which I/O tags are accessed, as in using the Symbol Class? Is it not Assembly Class? I have read that while doing implicit messaging, Assembly Class is used to access the I/O tags, is it different for the explicit messaging?

2. The services 0x4c and 0x4d are specific to Symbol Class?

3. How to know what are the instances and attributes present in this class?
 

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