Modicon TSX57 Memory Insight needed

[Manglemender]

I'm in need of some insight regarding the memory structure of a Modicon PLC.

In the program %M130 is being SET and RESET in ladder logic but elsewhere in the program %MW130 is also referred to in an "OPERATE" instruction.

How is the memory organised? Does setting %M130 set all bits in %MW130 to 1?

Please see attached code.

Thanks in advance,

Nick

 

[Liam Moran]

%M130 is a bit, %MW130 is a word.
They are not related. The format for the bits in a word are for example %MW100:X0 as being the least significant bit, and %MW130:X15 is most significant.

The operate instructions in your case are table instructions.
To describe the following:

%MW130:10:=%MW120:10

The contents of a table 10 words long, starting at %MW120 is transferred or moved to a table 10 words long starting at %MW130.

contents of %MW120 to %MW130,
contents of %MW121 to %MW131,
etc.


Deciphering the following instruction:

%MW110:10:=0

Value of 0 transferred or moved to a table, 10 words long, starting at %MW110, meaning %MW110 to %MW119 are loaded with the value 0

One of my favourite all time machines, the TSX57.
If you need any more help, just let me know.

 

[Manglemender]

Liam, Thanks very much for your reply, it was most helpful. We are converting an old Modicon system to Siemens Step7. We'll continue to try and understand the oroginal code.

Nick