If you configure DP slaves in a CPU, which are not actually present or not currently
required, the CPU will nevertheless continue to access these DP slaves at regular inter-
vals. After the slaves are deactivated, further CPU accessing will stop. In this way, the
fastest possible DP bus cycle can be achieved and the corresponding error events no
longer occur.
Every one of the possible machine options is configured as a DP slave by the manufac-
turer in order to create and maintain a common user program having all possible options.
With the SFC 12, you can deactivate all DP slaves, which are not present at machine
startup.
The SFC 12 operates asynchronously, in other words, it is executed over several SFC
calls. You start the request by calling the SFC 12 with REQ = 1.
The status of the job is indicated by the output parameters RET_VAL and BUSY.
If you have started a deactivation or activation job and you call the 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 inter-
preted as a follow-on call.
When you deactivate a DP slave with the SFC 12, its process outputs are set to the con-
figured substitute values or to "0" (secure state).
The assigned DP master does not continue to address this DP slave. Deactivated DP
slaves are not identified as fault or missing by the error LEDs on the DP master or CPU.
The process image of the inputs of deactivated DP slaves is updated with 0, that is, it is
handled just as for failed DP slaves.
With VIPA you can not deactivate all DP slaves.
At least 1 slave must remain activated at the bus.
If you are using your program to directly access the user data of a previously deactivated
DP slave, 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 with SFC (i.e. SFC 59 RD_REC), you
receive the error information in RET_VAL as for an unavailable DP slave.
Deactivating a DP slaves 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 does not start the slave failure OB 86, and the operating system
also does not make an entry in the diagnostic buffer. If a DP station fails after you have
deactivated it with the SFC 12, the operating system does not detect the failure. As a
result, there is no subsequent start of OB 86 or diagnostic buffer entry.
The station failure is detected only after the station has been reactivated and indicated in
RET_VAL.
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.
Application
Example
How the SFC operates
Identifying a job
Deactivating DP slaves
VIPA SPEED7
Integrated Standard
System Functions > SFC 12 - D_ACT_DP - DP-Activating and Deactivating of DP slaves
HB00 | OPL_SP7 | Operation list | en | 18-30 654
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