Technical data

Table Of Contents
SFBs for Compact CPUs
System Software for S7-300/400 System and Standard Functions - Volume 2/2
A5E00739858-01
28-53
Instance DB
The SFB FETCH_RK operates in combination with an instance DB. The DB
number is passed on with the call. Access to the data in the instance DB is not
allowed.
Special Features for (Expanded) Data Blocks
Note the following special features when "Fetching Data" from a data block or an
expanded data block:
With RK512 you can only send an even number of data. An additional byte is
transmitted if you enter an odd length (LEN). In the target DB, however, always
the correct number of data is entered.
In RK512 you can only declare an even offset. If you declare an odd offset the
data are stored in the partner station as of the next smaller even offset.
Example: Offset is 7, the data are stored as of byte 6.
Special Features for Timers and Counters
When you fetch times or counters from your communication partner, you must take
into account that you need to fetch two bytes for every time or counter. For
example, if you want to fetch 10 counters you must declare a length of 20.
Parameters
Note: In this SFB the range of values are all represented in the German memory
conventions.
Parameters Declaration Data
type
Range of
values
Default Description
SYNC_DB
INPUT INT CPU specific,
zero is not
allowed
0 Number of the DB in which
the common data for the
synchronization of the RK-
SFBs are stored (minimum
length = 240 bytes).
REQ
INPUT BOOL TRUE/FALSE FALSE Control parameter "Request":
Activates the job at the
positive edge.
R
INPUT BOOL TRUE/FALSE FALSE Control parameter "Reset".
Job is aborted.
LADDR
INPUT WORD CPU specific W#16#03FF The I/O address of your
submodule, specified by you
in "HW Config".
R_CPU
INPUT INT 0 to 4 1 CPU number of the partner
CPU
(only for multiprocessor
operation)