Technical data

SFBs for Compact CPUs
System Software for S7-300/400 System and Standard Functions - Volume 2/2
28-52 A5E00739858-01
28.10 Fetching Data (RK 512) with SFB 64 "FETCH RK"
Description
SFB FETCH_RK (SFB 64) is used to fetch a data block from a partner and store
them in a data block.
The send operation is executed after the block is called and a positive edge on
control input REQ.
The area in which the fetched data is stored is declared in RD_1 (DB number and
start address). The length of the data block is declared in LEN.
In the SFB you also specify the partner area from which the data are fetched. The
CPU enters this information in the RK512 message frame header and transfers it to
the partner.
The partner area is determined by the CPU number in R_CPU (only relevant for
multiprocessor communication), the data type in R_TYPE (data blocks, expanded
data blocks, memory bits, inputs, outputs, counters and times), the data block
number in R_DBNO (only relevant for data blocks and expanded data blocks) and
the offset in R_OFFSET from where the first byte is to be fetched.
In R_CF_BYT and R_CF_BIT you declare the connection memory byte and the
connection memory bit on the partner CPU.
In parameter SYNC_DB you declare the DB in which the data that you used in all
SFBs for the initialization during startup and synchronization is to be stored. The
DB numbers must be identical for all SFBs in your user program.
To enable the SFB to process the job, you must call it with R(Reset)=FALSE. At
the positive edge on control input R the current transmission is cancelled and the
SFB is reset to basic state. An cancelled job is closed with an error message
(STATUS output).
For your submodule, you declare the I/O address, which you specified in "HW
Config", in LADDR.
DONE is set TRUE if the job was terminated without error, or ERROR is set TRUE
if the job was terminated with an error.
In STATUS, the CPU indicates an error or, as a result of a warning, the respective
event ID.
DONE or ERROR/STATUS are also output when the SFB is RESET (R=TRUE).
The binary result BIE is reset if an error has occurred. The status of the binary
result is TRUE if the block was terminated without error.
Note
A parameter check is not included in the SFB. The CPU might go to STOP mode if
the configuration is faulty.
Note
When data are fetched from your CPU, you must program the SFB "SERVE_RK"
for your CPU.