why use structured text and function block over Ladder

[AdamG8GXP]

I'm hope this picture turns out OK. I kinda hacked it together. Since Ron was kind enought to show off some of the AB side languages I figured I would throw some Siemens up there.
From Left to Right:
LAD - Ladder editor
FBD - Function block
STL - Statement list
SCL - Structured control language

Also there is Graph but I have never used it.

The images for LAD, FBD and STL are all of the same rung. The SCL image is of something random but shows the basic structure.

Is there a picture like that that one can see what is in it?

 

[aidamcg]

An advantage over ladder with AB structured text is that the comments are loaded into the controller on download so will be available when uploaded if you don't have original project file. The disadvantage is that the comments take up memory which may be an issue on large programs. Also online editing of structured text is much slower than ladder as the entire routine has to be taken out for editing. It is slow to troubleshoot as you have to hover over each tag to get its value. As said in other posts I find it most useful for math and where a loop is required
Aidan