STL - Better than Ladder or Just job security?

Mike_Fantastic · Jan 28, 2011

I am new in a company which uses only Siemens. All the PLC programs I have uploaded are in statement list and cannot be reverted to ladder (no NOP 0s). Is statement list able to do something ladder cannot, or did someone wipe out all the NOP 0 lines for job security? How often do you guys encounter programmers who prefer STL over Ladder? should I stop programming in ladder and start learning STL?

Any guidance is greatly appreciated.

Mike.

JRW · Jan 28, 2011

Mike_Fantastic said:
I am new in a company which uses only Siemens. All the PLC programs I have uploaded are in statement list and cannot be reverted to ladder (no NOP 0s). Is statement list able to do something ladder cannot, or did someone wipe out all the NOP 0 lines for job security? How often do you guys encounter programmers who prefer STL over Ladder? should I stop programming in ladder and start learning STL?

Any guidance is greatly appreciated.

Mike.

You said "uploaded"
Under the blocks folder, does the created in language say STL?

Are your machines from Europe?

If your answers are yes- then learn STL

Mike_Fantastic · Jan 28, 2011

the answers are Yes & Yes.
I guess its time to learn STL. Why do the Europeans use STL instead of ladder?

JRW · Jan 28, 2011

As far as I know its what they are taught
and indirect addressing is only done in STL

Whats the created in language say??

Mike_Fantastic · Jan 28, 2011

It's all created in STL and SCL. I know Omron and AB have similar options (mneumonics) but every machine i ever worked on used ladder. is Siemens the only manufacturer that encourages writing programs in machine type language?

JRW · Jan 28, 2011

Mike_Fantastic said:
It's all created in STL and SCL. I know Omron and AB have similar options (mneumonics) but every machine i ever worked on used ladder. is Siemens the only manufacturer that encourages writing programs in machine type language?

----------------------------------
Well SCL (Structured Control language) is the same as ST or Structured Text
STL (Statement List) is the same as IL or Instruction List
Many manufacturers have this.

I use "same as" kinda loosely

Anyway, if alot of your blocks are SCL and you uploaded your program THEN you will not have the source code. Thus you can only read the code in STL
I hope that makes sense...

The long short of it is- GET THE ORIGINAL CODE FROM YOUR VENDOR

Mike_Fantastic · Jan 28, 2011

Thank you JRW. What i now understand is that if i want to work with Siemens PLCs i must learn statement list.

Thank you!

TConnolly · Jan 28, 2011

Don't be daunted about learning it. There will be things you will like about it.

V0N_hydro · Jan 28, 2011

use the right tool for the job.
It is more difficult to write certain types of loops, like signal processing, in ladder than STL.

Peter Nachtwey · Jan 28, 2011

Learn SCL

I would use mostly SCL because of the ease of programming. For those things that MUST be fast I would write first in SCL and then optimize the STL code by hand. Writing code in STL is like writing code in assembly language. It is tedious and more error prone than writing it in a higher level language.

There will be some things that still must be done in STL but they can usually be very small functions.

My answer to your question is that writing code in STL provides job security.

geniusintraining · Jan 28, 2011

Peter Nachtwey said:
My answer to your question is that writing code in STL provides job security.

I password is job security.... STL is very fast if you are programming it and have learned it first or with ladder

It like talking on the phone with someone

and pushbutton
and not estop
or stop
= run

Learn it and have fun with it... open another empty block or window and then you can copy and paste the hard ones into the empty project, there you can add your NOP's and convert it into ladder

The long short of it is- GET THE ORIGINAL CODE FROM YOUR VENDOR

:nodi: YES YES YES

Peter Nachtwey · Jan 28, 2011

Your example is trivial

geniusintraining said:
I password is job security.... STL is very fast if you are programming it and have learned it first or with ladder

It like talking on the phone with someone

and pushbutton
and not estop
or stop
= run

You forgot the parentheses around the estop and stop. Oops, have fun chasing that bug down. It is easier to make errors in STL. It is harder to see the program structure since there is no indenting.

In SCL
run:=pushbutton and not ( estop or stop )

TurpoUrpo · Jan 29, 2011

geniusintraining said:
and pushbutton
and not estop
or stop
= run

Learn it and have fun with it...

^^

Peter Nachtwey said:
You forgot the parentheses around the estop and stop. Oops, have fun chasing that bug down. It is easier to make errors in STL. It is harder to see the program structure since there is no indenting.

In SCL
run:=pushbutton and not ( estop or stop )

No Peter, above stl (or did you intend to say what it should be?)

Code:

a pushbutton
an estop
o stop
= run

Would be:

Code:

run := (pushbutton and not estop) or stop;

Btw, where ever one could use something like that

STL is hard. I would actually say that concepts behind it that make it superior in some cases, are so hard that not everyone really can understand them. But if one can, he on the way learns S7 inner workings so that it is worth it. If you use another languages you don't need to understand anything about accus, registers etc.

Peter Nachtwey · Jan 29, 2011

So when stop is true then run is true. It doesn't make sense.

TurpoUrpo · Jan 29, 2011

Peter Nachtwey said:
So when stop is true then run is true. It doesn't make sense.

Ofc it does not make sense, but that is how he did write it.

STL - Better than Ladder or Just job security?

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