Siemens SINUMERIK 840D sl Function Manual page 1422

Detailed description
2.12 Block descriptions
2.12.5 FB 5: GETGUD read GUD variable
Description of functions
The PLC user program can read a GUD variable (GUD = Global User Data) from the NCK or
channel area using the FB GETGUD. The FB is multi-instance-capable. The call is permitted
only in cyclic program OB1. An assignment for all parameters with Req = 0 is also permitted
in OB100. Capital letters must be used for the names of GUD variables. Every FB 5 call
must be assigned a separate instance DB from the user area.
A job is started when FB 5 is called by means of a positive edge change at control input Req.
This job includes the name of the GUD variable to be read in parameter "Addr" with data
type "STRING". The pointer to the name of the GUD variables is assigned symbolically to
the "Addr" parameter with <DataBlockName>.<VariableName>. Additional information about
this variable is specified in parameters "Area", "Unit", "Index1" and "Index2" (see table of
block parameters).
When parameter "CnvtToken" is activated, a variable pointer (token) can be generated for
this GUD variable as an option. This pointer is generated via the VAR selector for system
variables of the NC. Only this method of generating pointers is available for GUD variables.
Once a pointer has been generated for the GUD variable, then it is possible to read and write
via FB 2 and FB 3 (GET, PUT) with reference to the pointer. This is the only method by
which GUD variables can be read. When FB 2 or FB 3 is parameterized, only parameter
Addr1 ... Addr8 need to be parameterized for the GUD variable pointer. GUD variable fields
are an exception. In these, Line1 .. Line8 must also be parameterized with the field index of
this variable.
Successful completion of the read process is indicated by a logic "1" in status parameter
"Done".
The read process extends over several PLC cycles generally 1 to 2).
The block can be called up in cyclic mode only.
Any errors are indicated by Error and State.
Note
FB 5 can read GUD variables only if basic program parameter NCKomm has been set to "1"
(in OB 100: FB 1, DB 7) see Section "FB 2: Read GET NC variable
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Basic logic functions: PLC basic program solution line (P3 sl)
Function Manual, 11/2006, 6FC5397-0BP10-2BA0