The Fb 252 Block Transfer Block - Siemens SIMATIC S5 Manual

S5-115F Manual
6.1.4

The FB 252 Block Transfer Block

FB 252 handles control of data transfer between the CPU and the CP 523 serial input/output
module. FB 252 transfers fixed-length data. Up to 32 data blocks of eight bytes each are read out
of or written into the memory area per call. Memory areas are data blocks or flag areas.
Parameter Meaning
BADR Initial module
address
FUNK Function
TYP Memory type of
source/destina-
tion in the case
of S/R
DBNR Block number
ANFA First word of
data block or
flag area
BLCK Number of
blocks
Indirect assignment of FB 252 parameters
If you want to assign the FB 252 parameters indirectly, store the six block parameters in a data
block in consecutive data words. Please note the order of the parameters!
When calling FB 252 you must also specify the following:
• The value "XX" in the parameter type
• The number of the DB (DB 4 to 255) with the block parameter assignments for the DBNR
parameter
or
the value "C" for the DBNR parameter if the last opened DB contains the block parameter
assignments
• The number of the data word containing the first block parameter (BADR parameter) for the
ANFA parameter.
The BADR, FUNK and BLCK parameters must be assigned permissible values but the values them-
selves are insignificant in this case.
EWA 4NEB 811 6149-02
Type Data
Type
D KF 128 to 248
(in eight-byte steps)
D KC S: = Send data
R: = Receive data
D KC D: = Data block
F: = Flag area
XX: = Indirect block initialization
(the block parameters are
stored in a data block)
D KF In the case of data block:
In the case of flag area:
in the case of indirect block
Initialization: 0; 4 to 255
D KF In the case of data block: 0 to 252
In the case of flag area: 2 to 248
D KF 1 - 32
Specification of eight-byte data
blocks sent/received
Assignment
4 to 255
0
Blocks
STL
: JU FB 252
NAME : AGF: BLUE
BADR :
FUNK :
TYP :
DBNR :
ANFA :
BLCK :
6-9