about the usage of SFC59

could somebody explain the parameter RECNUM in detail?

is there any regulation to specify this parameterfrom 0to 240?

such as which situation does RECNUM=1 stand for, and 2, 3, 4...and so on.

thank you!

Some modules have asystem data area fromwhich your program can

readdata records. This area contains data records with numbers from 0 to a

maximum of 240. Not every module contains all of the data records.

Chapter 7 of this manual http://support.automation.siemens.com/WW/view/en/1214574explain the basics. On page 7-2 you have a table. There you will see that records 0 and 1 deliver diagnostic data.

The content of the diagnostic data for each module is in the manual of that module.
For the standard modules of S7-300 for instance, in this manual http://support.automation.siemens.com/WW/view/en/8859629
in appendix B, you will find the detailled description.

I hope this help