Step7 LAD>STL

[Disciple]

The process of converting LAD to STL is upon me.
The Bit Logic Instruction:
A( And with Nesting Open, saves the RLO and OR bits and a Function code into the nesting stack.

What does this do in Layman Terms?

 

[Disciple]

Step7 LAD.STL

In reference to the 2 Attachments;Network#1
LAD#1 Network #1 is clearly understood.
STL#1 Network #1 is also pretty straight forward, Just wondering what all the Text after the :
=L or Assign Load Current Timer Value into ACCU 1 as Integer.
BLD(Program Display Instruction) 103?
Is Call AH_TMR the actual "Call of the Timer?
Is IN:=L0.0 actually Assigning the value 0.0 into IN Input on said Timer?
Is PT:=#AH_TM actually loading the value of Alarm Horn Time,(5.0 sec) into the Preset Time on the said Timer? This Value was predetermined as the Initial Value in the Variable Table.
And Almost there:
Q:=#A_EN will allow Area Enabled?
And to bring it home:
ET:=
NOP 0 Null Instruction? Not sure about this,but Logic Dictates End of Program Instruction????
Lets Hear from the Pro's & the Cons!

 

[RMA]

The "= L0.0" in NW1 is storing the result of the preceding logical operation (RLO) in temporary (Local) storage with the address 0.0.

The BLD instruction is an internal instruction used by Step7 to construct the graphical representation in Ladder and FBD - BLD is a short form of the German "Bild" which is "picture" or "screen" in English.

As you assume, the CALL instruction is calling the timer to execute it.

IN := L0.0 is picking up the previously stored RLO and feeding it to the inut of the Timer

and as you assume PT := #AH_TM is loading the Time from Local Variable AH_TM

Q is the output of the Timer and is driving local variable A_EN.

ET is the elapsed time when the Timer is running and is not being used in this example.

NOP is the command "No Operation" or Null instruction if you prefer. I assume it's a filler for the missing operand for ET, although I'm not sure why it's on the following line.

This is one of the reasons that you can't always switch STL code to LADder - every input and output of a function must be listed - with a NOP if it's not being used and most people don't do this when they programm in STL.

 

[L D[AR2P#0.0]]

The process of converting LAD to STL is upon me.
The Bit Logic Instruction:
A( And with Nesting Open, saves the RLO and OR bits and a Function code into the nesting stack.

What does this do in Layman Terms?

The nesting stack is used to evaluate the logic state at each closing branch. See example code below: