Siemens STL & Language Issues

There's conversion from lad to stl never tried lad to scl.

An there's conversion from stl to lad. Only really works with very simple routines.

Rob... said:

There's conversion from lad to stl never tried lad to scl.

An there's conversion from stl to lad. Only really works with very simple routines.

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Or if the STL is written so that the converter understands it. I never managed to, but had a colleague of mine that could write STL that would be converted correctly to the other languages in Step7.

I need to see if I can find that conversion in TIA Portal.

mk42 said:

I'm glad to be seeing a lot more acceptance of SCL in the newer generation of controls engineers. More guys coming in with a programming background at some point in their schooling.

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Me too... hence why I think some brands are bound to suffer and a lot by making these languages an add-on or not even available. Ladder is the best language to display Boolean logic, followed closely by SCL if the programmer formats the code nicely, but is definitely not the right language for complex stuff that is more and more common in control systems.

You can only do conversion between LAD/STL if you do it on a 300/400 controller in the TIA project, not a S7-1500. At least not in TIA 13/14, haven't bothered unwrapping the TIA 15 disks yet.

If you have STL specific instructions (like memory swapping) or double assignments in the same part, you can't convert it either.
But something like a simple
LD M0.0
A I0.0
= Q0.0
is fine.

I have made two projects now with precise motion control written in ladder. Ended up with multiple function blocks written in SCL and just tossed it in there to overcome the insanity. Never again.

And just you try to convert a function block written in STL or LAD to another platform.

CommissioningMan said:

But something like a simple
LD M0.0
A I0.0
= Q0.0
is fine.

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Are you sure? What is LD supposed to do?

CommissioningMan said:

And just you try to convert a function block written in STL or LAD to another platform.

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I don't think porting code between platforms is high in the list of requirements from each manufacturer.

cardosocea said:

I don't think porting code between platforms is high in the list of requirements from each manufacturer.

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There have been a couple efforts to have cross platform compatibility, but nothing that gets adopted across the board.

Originally there was IEC 61131-3, trying to standardize the languages, and then there was PLCOpen trying to standardize instructions. Both of these are given lip service by most vendors, but they are treated more as guidelines than as rules. Most vendors take the concepts they like, and then extend them with their own concepts. Few PLC vendors are willing to limit themselves to the concepts that got through the committee, and many others are resistant to implementing new concepts.

AutomationML is a newish attempt to combine PLC code, HW design, and more into an XML model that can be shared. I know Siemens and Eplan claim to use it as an interface, but I don't know if any other vendors have implemented it, or how compatible the implementations could be.

cardosocea said:

Are you sure? What is LD supposed to do?

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Just a typo. First I used a L for load value, but changed it to just a bit compare, but didn't change the instruction, typo remained.
Point is: something simple can be converted just fine. Make a new project with a S7-300 controller and try it out yourself.

cardosocea said:

I don't think porting code between platforms is high in the list of requirements from each manufacturer.

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No, not manufacturer, end user. We use 4-5 different platforms and when you have a lot of standard function blocks written and tested ages ago, you don't want it in ladder, because you can't copy paste it to another platform. With Structured Text, you don't need too much editing after copying.