Technical data

Table Of Contents
SFCs for Distributed I/Os or PROFINET IO
System Software for S7-300/400 System and Standard Functions - Volume 1/2
16-4
A5E00709327-01
16.2 Synchronizing Groups of DP Slaves with SFC 11
"DPSYC_FR"
Description
With SFC 11 "DPSYC_FR," you can synchronize one or more groups of DP slaves.
The function involves sending one of the control commands below or a
combination of them to the relevant groups:
SYNC (simultaneous output and freezing of output states on the DP slaves)
UNSYNC (cancels the SYNC control command)
FREEZE (freeze the input states on the DP slaves read in the frozen inputs)
UNFREEZE (cancels the FREEZE control command)
Note
Note that the control commands SYNC and FREEZE also remain valid when you
perform a restart/warm restart.
Please note also that you may initiate only one SYNC-/UNSYNC request or only
one FREEZE/UNFREEZE request at a given time.
Requirements
Before you send the control commands listed above, you must assign the DP
slaves to groups using STEP 7 (see /231/). You must know which DP slave is
assigned to which group with which number and know the reactions of the various
groups to SYNC/FREEZE.
How the SFC Operates
SFC 11 "DPSYC_FR" is an asynchronous SFC; in other words, its execution takes
several SFC calls. You start the job by calling SFC 11 with REQ=1.
The status of the job is indicated by the output parameters RET_VAL and BUSY,
also refer to Meaning of the Parameters REQ, RET_VAL and BUSY with
Asynchronous SFCs.
Identifying a Job
If you have triggered a SYNC/FREEZE job and called SFC 11 again before the first
job was completed, the response of the SFC depends on whether the new call is
for the same job. If the input parameters LADDR, GROUP and MODE match, the
SFC call is interpreted as a follow-on call.