PLC STL Understanding.

[parco]

Dear frinds,
hello all,
kindly any body from PLC world can help me regardign how can i read & understand PLC program in STL formate, and kindly define the following legends, is it possible to convert STL to Ladder formate, i need meaning of these LEGENDS .this is A programe kindly make it easy how to Understand it,

net work:
O M 83.5
O A 44.1
U DB5.DBX20.3( WHAT IS THIS ).
UN DB5.DBX151.2
S DB5.DBX151.4
UN M 83.5
UN A 44.1
U A 40.0
U DB5.DBX151.4
O DB5.DBX151.2
R DB5.DBX151.4

GIVE ME HINT HOW CAN I READ THIS PROGRAM N MEANING OF LEGENDS USED IN THIS PROGRAM.

 

[PLucas]

parco

It looks like you are using the German mnenomics, I only work in English so I don't know the German ones.

Anyway, you were asking about:-

U DB5.DBX20.3

The U stands for AND (I assume that is AND, as I stated I don't know the German mnenomics), the DB5.DBX20.3 is the address of the bit in Data Block 5, Data Byte 20 bit 3.

If for example you wanted to address a bit in data block 100, byte 4 bit 6, it would look like this:-

A DB100.DBX4.6

Does that help?

Paul

 

[dchartier]

Hello parco;

If you have step 7 installed on your computer, you will find a STL manual in your Simatic/Documentation folder. You could also download it (Working with STL) from Siemens' support website.

Let's look at your program snippet:
(German)(English)
U ---> A = AND ---> --[ ]--
O --> O = OR --> branch down
UN --> AN = AND NOT --> --[/]--
R --> R = Reset --> --[R]--
S --> S = Set --> ----

You will also find :

= --> = = Output coil --> --( )--

Addressing:
M addresses refer to internal flags or registers
A (Ausgang) refers to outputs
E (Eingang) refers to inputs
DB refer to Data Blocs, as Paul explained earlier

Here is a translation from STL to ladder (Notice it requires 2 netyworks in ladder; purists would say this is one advantage of STL, compact code):

Hope this helps,
Daniel Chartier