Siemens SINUMERIK 840D sl Function Manual page 1101

2.12.3 FB 3: PUT write NC variables
Description of functions
The PLC user program can write variables in the NCK area using FB PUT.
Every FB 3 call must be assigned a separate instance DB from the user area. (multiinstance
capability in SW 3.7 and higher).
When FB 3 is called with a positive signal edge change at control input Req, a job is started
to overwrite the NC variables referenced by Addr1 to Addr8 with the data of the PLC
operand areas locally referenced by SD1 to SD8. Successful completion of the write process
is indicated by a logical "1" in status parameter "Done".
The write process lasts for several PLC cycles (normally 1-2). The block can be called up in
cyclic mode only.
Any errors are indicated by Error and State.
In order to reference the NC variables, all required variables are first selected with the "NC
VAR selector" tool and generated as STL source in a data block. A name must then be
assigned to this DB in the symbol table. "DB name.S7 name" is transferred as the actual
parameter of the NCK variable address (Addr1 to Addr8) when FB3 is called.
Variable addressing
For some NC variables, it is necessary to select area no. and/or line or column in the NC
VAR selector. A basic type can be selected for these variables,
i.e., area/column/line are preset to "0".
The contents of the area number, line and column specified by the NC VAR selector are
checked for a "0" in the FB. If a "0" is present, the value is transferred to the input parameter.
The user must supply the required parameters (UnitX/ColumnX/LineX) before calling
FB PUT.
Basic logic functions: PLC Basic program powerline (P3 pl)
Function Manual, 11/2006, 6FC5397-0BP10-2BA0
Detailed description
2.12 Block descriptions
117