Hello.

I found out that in one old program I used arrays in the M area like M[Adr, BitNr] and MW[adr] without any array definition (adr from 0 to 255). Worked perfectly! The small program inside just one OB without any additional Data blocks.

The questions is about the data types.

1.It seems that in symbol table I cannot define the arrays?

2.If I just use it like the mentioned above the data will always be in the Word format ?

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Split from MEMORY AREA.

Aivars

Thanks, qwazee!

I started the programing with machine codes and assembler. There the use of indirect addressing and pointers were simple and clear. Now it seems that each generation of PLC has different approach!

So if I understand correctly there are at least 3 different programming versions for the same solution.

1.The old STEP7 for S7-300/400. It seems there are newer version of STEP7 available for Win10 and up. Do they work the same way as the “classic” one?

2.The TIA portal professional that supports S7-300/400

3.The TIA portal Basic/Professional for S7-1200/1500

I use the SCL not the STL.

You are close to correct about the types of Step7.

1) The classic series is designated with the version number 5.x. V5.7 is the latest and does work on Windows 10 and 11. All the old and current S7-300 and S7-400 based processors can be programmed. The classic Step7 software (V5.0 - V5.7) is less restrictive going up/down software versions.

2) The Step7 module in the TIA Portal "famework" can program S7-1200, S7-1500, S7-300 and S7-400 based processors. There are two tiers of licenses; basic license only allows programming S7-1200; professional license allows all.

2.1. Some code formatting changes occurred for the S7-300 and S7-400. The links provided before mentions this. The command set and capabilities in TIA Portal remains as in the classic software. Not all S7-x00 processors can be programmed. Each TIA Portal version drops some more of the older S7-x00 versions of processors (and peripherals).

2.2 The S7-1500 is a different infrastructure. Some functionality like the S7-x00 is retained for compatibility purposes but much is not available. Register functionality of STL is emulated with a performance penalty. Indirect addressing (especially in STL) should be avoided. 

2.3 The S7-1200 does not even try to be compatible with the S7-x00. STL is not even offered. A rework of concepts is needed when porting over S7-x00 code that depended on indirect addressing. The oldest S7-1200 versions cannot be programmed with the newest version of Step7 V1x.

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Indirect addressing of the memory bit area is possible in TIA Portal; the format changed for the S7-x00 and the S7-1x00 uses PEEK/POKE instructions. Designers are encouraged to use arrays within DBs.

The S7-1x00 offers performance enhancements when using optimized data structures. Movement of data structures also becomes very easy in the S7-1x00 series.