Step 7 Statement List Calculations

Hi All,

I have a task to decipher a calculation done by one of our S7 PLC's onsite. The problem being that its in statement list, and this programming language is something that i'm not all that familiar with. I have moved the Code into Excel and started to attempt to breakdown the calculations, however i'm not sure how to handle the parts that include the TAK Mnemonic. (I'm not all that sure I even have the first parts correct). I'm hoping someone could have a look at the spread sheet and add the formula's on the Right hand side like I have done. Hopefully then I can see how the statement list calculations are done.

Any help would be greatly appreciated,

Here's some test setpoint data and the results from your code executing:

Here's the accumulators when the code is executing:

compiled by SCL compiler version: SCLCOMP K05.03.08.00_01.05.00.01 release

Click to expand...

Don't you have the original SCL source code in any project?

interesting comment language btw...

TAK is just swapping ACCU1 with ACCU2. Values from ACCU1 goes to ACCU2 and values from ACCU2 goes to ACCU1. Important for - and / calculations, not so much for + and *.
Code needs optimization tbh.


Can be replaced with:


In the original code you perform a -R, this value is stored in ACCU1. Then you load #sp4, which pushes the calculation result to ACCU2 and loads the value from #sp4 in ACCU1. After that a TAK is performed which swaps ACCU1 and ACCU2. So the calculation result is in ACCU1 again, which is transferred to LD 62. Then there is another TAK which again swaps ACCU1 and ACCU2 so now the value from #sp4 is back in ACCU1 and ACCU2 contains the calculation result

The far simpler "transfer to LD62 then load #sp4" has the exact same end result.