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User Defined Data Types (UDTs) and OOP

by John Schop For years now, Object Oriented Programming paradigm (or OOP) has been a commonly used programming practice, and has of course found its way into industrial automation as well. In the mean time, most PLC manufacturers ...

Story - Tim Young - 2008-12-10 17:02 - 6 comments

Statement List (STL) Cheat Sheets

If you are a Siemens PLC user then you've more then likely have run into Statement List (STL) programming. STL corresponds to the Instruction List language defined in the IEC 61131-3 specification. The programming is done with very simple mnemon ...

Book page - Tim Young - 2007-10-29 10:45 - 0 comments

Modbus FAQ

... master can address individual slaves, or can initiate a broadcast message to all slaves. Slaves return a message (response) to queries ... for the master's query by placing into it the device (or broadcast) address, a function code defining the requested action, any data to ...

Story - Tim Young - 2006-06-01 22:05 - 3 comments