Statement list to ladder Siemens S7


Thread Starter


Is there any reasonably simple/easy way of converting SL to ladder. Somebody suggested that commercial software exists that can do this.
Trying to 'spot' a problem with a machine whilst observing online in statement list is well nigh impossible.
The Siemens programming software will convert IL (statement list) to ladder automatically if that is at all possible. You can select the mode from one of the menus.

However, it is possible to write IL in such a way that there is no possible ladder representation for the complete rung. In addition, if you are using the S7-300 or S7-400, there are many instructions which do not have ladder symbols.

The problem (also common with S5 programs) usually stems from a combination of the original programmer being very, very familiar with IL and not caring if the program can be displayed in ladder, and the fact that some instructions can't be written in ladder. In that case, the fastest way for them to write the program is to stuff the equivalent logic of several rungs into one.

Most of the time the solution is to break up the contents of each rung into several smaller ones. That typically doesn't require more instructions. Rather it just means the same instructions split between two or more separate rungs. You can write very readable and understandable ladder programs for an S7-300/400 PLC, it just takes a bit more effort.

With the S7-200, all instructions have ladder equivalents, but it is still possible to write IL which cannot logically be represented in ladder format. However, I've never seen an S7-200 program that was written using anything other than 100% ladder.

Luca Gallina

Step7 rungs' graphic representation must strictly obey to some syntax rules normally managed by the graphic editor itself. The graphic editor manages also the "carry" of temporary logic results by using directly addressed local data.

In other words, the answer to your question is "no".

Kind regards
Luca Gallina