# OPC connections between Ignition and Siemens PLC

**URL:** <https://forum.inductiveautomation.com/t/opc-connections-between-ignition-and-siemens-plc/73887>\
**Category:** Ignition\
**Tags:** ignition81, perspective\
**Created:** [May 18, 2023, 10:58am UTC](https://forum.inductiveautomation.com/t/opc-connections-between-ignition-and-siemens-plc/73887 "2023-05-18T10:58:57Z")\
**Posts on this page:** 1\
**Showing post:** 12

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**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\
**Post date:** [May 24, 2023, 12:36pm UTC](https://forum.inductiveautomation.com/t/opc-connections-between-ignition-and-siemens-plc/73887/12 "2023-05-24T12:36:43Z")

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Another thing I will mention, since I missed that this was a S7-1200, is that via the “Server Interface” mechanism Ignition will not be able to read whole structures, only individual exposed structure members. I can’t remember if the 1200 exposes these or not, but it’s not ideal performance-wise for the PLC.

This is because the 1200’s Service Interface mechanism only supports the newer DataTypeDefinition attribute, and not the older DataType Dictionary mechanism, that let’s clients learn about structured types in the server.

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