LAD SCL STL language restrictions

He asked "what do you mean" to your comment "You should also include Statement List".
Statement list is STL in Siemens-lingo, and IL in IEC-lingo.

Imo, STL in Siemens should be phased out.
Afaik, IL in IEC is usually not supported on the various platforms that are based on IEC61131-3, or half-heartedly supported at best.
 
geniusintraining said:
I think that is the issue... STL is a half *** version of ST, I think they should make it better not get rid of it
Click to expand...




IL = STL


ST = SCL




IL is actually supported by Schneider's PLC, but I have not seen it used much.


FBD (LOGIGRAM) is also rarely seen but supported. I don't think I have seen any FBD program outside process installation (chemical by exemple).
 
Iner said:
FBD (LOGIGRAM) is also rarely seen but supported. I don't think I have seen any FBD program outside process installation (chemical by exemple).
Click to expand...

I do not like FBD... you would think we should use it more, I think it easy to understand and maybe easier for the end user but I guess coming from up in the field as a electrician I would like to read ladder than than the blocks
 
Iner,

FBD in Modicon controllers is not the same as in Siemens and Codesys. The equivalent is CFC.
I believe CFC is an exceptional tool.
 
grnick50 said:
Iner,

FBD in Modicon controllers is not the same as in Siemens and Codesys. The equivalent is CFC.
I believe CFC is an exceptional tool.
Click to expand...


I am interested to know why.


I am like geniusintraining, I never use FBD/CFC, the only time I have used something that looked like that was in special safety PLC since it's required.


I generaly use:


LD: for logic control, outputs, memory
ST: for writing/reading files, text manipulation and commands, loops & array, scaling or calcul
SFC/Graph: for some highly sequential logic


LIST is/was necessary in some cases in STEP7.


I wonder if people who use FBD/CFC are using it mainly to generate alarms, opening/closing valves, actionning pumps, tuning PID like I have seen in continuous process applications. Or is it also used to control machines with conveyors, elevators, pneumatic cylinders, motion axis, robots, barcodes, printers, welder torch, lubricating, screwing and all ?


I don't know if it's a regional thing but I must admit I have never seen a machine coded in FBD/CFC.
 
geniusintraining said:
I do not like FBD... you would think we should use it more, I think it easy to understand and maybe easier for the end user but I guess coming from up in the field as a electrician I would like to read ladder than than the blocks
Click to expand...

I think the FBD style is better for people who come from a binary logic background instead of an electrical relay background for LAD. I think it's one of those EU vs USA things.

Personally I hate STL/IL, but love SCL/ST.

Back to OP's question, the differences depend entirely on your chosen PLC platform. As others have said, even within Siemens, your answer for 300/400 is very different from your answer for 1500.
 
mk42 said:
Back to OP's question, the differences depend entirely on your chosen PLC platform. As others have said, even within Siemens, your answer for 300/400 is very different from your answer for 1500.
Click to expand...

As far as I know, all languages in 300/400 are translated to STL. So I wonder if there's any point in comparing them in 300/400.
 
Iner said:
I wonder if people who use FBD/CFC are using it mainly to generate alarms, opening/closing valves, actionning pumps, tuning PID like I have seen in continuous process applications. Or is it also used to control machines with conveyors, elevators, pneumatic cylinders, motion axis, robots, barcodes, printers, welder torch, lubricating, screwing and all ?


I don't know if it's a regional thing but I must admit I have never seen a machine coded in FBD/CFC.
Click to expand...


I've used CFC exclusively in DCS (PCS7) programming. In there it does make sense as you see process blocks in a flow and understand easily what is wrong or how a pump/valve/etc is controlled.



The first time I ever saw CFC was on a drive system (basically a bunch of drives and other equipment) delivered by Siemens and they used CFC as the "glue" to bind it all together. So the blocks were written in whatever language they preferred, but the entire program structure was laid out in CFC sheets, which made the data transfer easy to do (drag and drop lines) and the whole process interconnection visible from the "top".



I don't think it makes sense to do low level logic in CFC, although I've seen people trying it.
 
mk42 said:
I think the FBD style is better for people who come from a binary logic background instead of an electrical relay background for LAD. I think it's one of those EU vs USA things.
Click to expand...
Blame Siemens for the preference of FBD over LAD. In S5, LAD was never properly implemented. There were serious limitations compared to FBD. Because of that and because of Siemens dominance many have been indoctrinated with FBD.
Personally I prefer LAD over FBD, I find LAD more graphical and intuitive to understand in a glance. When I went from S5 to S7 I immediately switched to LAD.
FBD is only "half-graphical". You have to read the description text (the "&" and the ">1") inside each "box" and in your head make out the logical meaning. Not so with LAD, it is 100% graphical.

As for CFC, just for completeness sake i must mention that CFC is not yet available in Siemens TIA.
Everything pertaining to PCS7 is not yet available in Siemens TIA.
I have seen other platforms with CFC or CFC-like programming languages. I did an ABB project nearly 30 years ago with a CFC-like programming language.
 
JesperMP said:
Blame Siemens for the preference of FBD over LAD. In S5, LAD was never properly implemented. There were serious limitations compared to FBD. Because of that and because of Siemens dominance many have been indoctrinated with FBD.
Personally I prefer LAD over FBD, I find LAD more graphical and intuitive to understand in a glance. When I went from S5 to S7 I immediately switched to LAD.
FBD is only "half-graphical". You have to read the description text (the "&" and the ">1") inside each "box" and in your head make out the logical meaning. Not so with LAD, it is 100% graphical.

As for CFC, just for completeness sake i must mention that CFC is not yet available in Siemens TIA.
Everything pertaining to PCS7 is not yet available in Siemens TIA.
I have seen other platforms with CFC or CFC-like programming languages. I did an ABB project nearly 30 years ago with a CFC-like programming language.
Click to expand...


Hilariously, CFC IS available in TIA.... just not for PLCs. If you use Simocode motor starters, the programming is done in CFC, since like V13.


CFC is kinda what I always thought FBD should have been. It annoyed me so much that you could connect binary pins, but not integer/real pins. It makes math look so kludgy, with a ton of extra temp tags for no reason. TO be fair, CFC has a crazy amount of overhead in the background, but its in the background and I don't have to care about it if I don't want to.
 
Now that I think of it, there's one that bothers me between Ladder and FBD.

In FBD you can invert the input of the block graphically, but in Ladder you have to insert the contact you want and put the variable on it. I agree that a dot on the block input would look weird for ladder minded people, but I hate inverting the signal with a contact on the input of the block. It looks clunky.
 
dwoodlock said:
In SCL you can use loops to run through arrays or structures and make changes or just analyze contents quite fast.


The other week there was actually a thread about someone trying to replicate this functionality in STL.
Click to expand...

Could You link this thread to me? It's been a while and I can't find it now
 

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