I, q, w, k, s

I'm a longtime Allen-Bradley user, so the Typed Data Table syntax that SLC-500 and PLC-5 controllers used is very familiar to me. The O0, I1, S2, B3, T4, C5, R6, N7, and F8 data files are totally normal and clear.

But I'm starting to work with some CoDeSys controllers (Turck BL67), which seem to have a mix of Tag-based IEC 1131 style variable names and physical controller memory that I think follows an addressing standard where everything begins with a percent symbol.

I'm beginning to understand the %I is input data, %Q is output data, %M is internal integer holding register data, and %S is Status data.

So the data tables are "Typed", like they are with A-B, because there are input and output and holding and status types.

But it looks like the data tables are a "flat file", and that you can designate whether you're looking at an offset by bit, byte, word, or dword based on the second letter, so it can be an X, B, W, or D.


What is this addressing convention called ? Where does it come from ? And can somebody point me to a concise tutorial on it that isn't in German ?

In IEC 1131-based systems you really don't have to bother about the actual allocation of the internal memory. Yes, this is just one large flat address space and, unless you need to do something special, the compiler will allocate your variables there.

%M is just the internal memory; whether it is treated as a bit, a byte, an integer, a double or a float depends on how each particular variable is declared.

Ken, I PM'ed you the name of my App Support guy at Turck.