Technical data

SFCs for Distributed I/Os or PROFINET IO
System Software for S7-300/400 System and Standard Functions - Volume 1/2
A5E00709327-01
16-11
How the SFC Operates
SFC 12 ”D_ACT_DP” operates asynchronously, in other words, it is executed over
several SFC calls. You start the request by calling SFC 12 with REQ=1.
The status of the job is indicated by the output parameters RET_VAL and BUSY;
see also Meaning of the Parameters REQ, RET_VAL and BUSY with
Asynchronous SFCs.
Identifying a Job
If you have started a deactivation or activation job and you call SFC 12 again
before the job is completed, the way in which the SFC reacts depends largely on
whether the new call involves the same job: If the parameter LADDR matches, the
SFC call is interpreted as a follow-on call.
Deactivating DP Slaves/PROFINET IO devices
When you deactivate a DP slave/PROFINET IO device with SFC 12, its process
outputs are set to the configured substitute values or to 0 (secure state). The
assigned DP master/PROFINET IO controller does not continue to address this
component. Deactivated DP slaves/PROFINET IO devices are not identified as
faulty or missing by the error LEDs on the DP master/PROFINET IO controller or
CPU.
The process image of the inputs of deactivated DP slaves/PROFINET IO devices is
updated with 0, that is, it is handled just as for failed DP slaves/PROFINET IO
devices.
If you are using your program to directly access the user data of a previously
deactivated DP slave/PROFINET IO device, the I/O access error OB (OB 122) is
called, and the corresponding start event is entered in the diagnostic buffer. If you
attempt to access a deactivated DP slave/PROFINET IO device with SFC (i.e. SFC
59 ”RD_REC”), you receive the error information in RET_VAL as for an unavailable
DP slave/PROFINET IO device.
Deactivating a DP slave/PROFINET IO device does not start the program error OB
(OB 85), even if its inputs or outputs belong to the system-side process image to
be updated. No entry is made in the diagnostic buffer.
Deactivating a DP slave/PROFINET IO device does not start the rack failure OB
(OB 86), and the operating system also does not make an entry in the diagnostic
buffer.
If a DP station/PNIO station fails after you have deactivated it with SFC 12, the
operating system does not detect the failure. As a result, there is no subsequent
start of OB86 or diagnostic buffer entry. The station failure is detected only after the
station has been reactivated and indicated in RET_VAL.
Applies to PROFIBUS DP: If you wish to deactivate DP slaves functioning as
transmitters in cross communication, we recommend that you first deactivate the
receivers (listeners) that detect which input data the transmitter is transferring to its
DP master. Deactivate the transmitter only after you have performed this step.