Entry type: FAQ, Entry ID: 19730984, Entry date: 11/23/2004
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Enabling a disabled DP slave with SFC 12 "D_ACT_DP"

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QUESTION:  
What happens when with SFC 12 I enable a disabled DP slave that is physically separated from the DP bus?

ANSWER:  
If you attempt to use SFC 12 "D_ACT_DP" to enable a disabled DP slave that is physically separated from the DP bus, for about 1 minute SFC 12 delivers the error code W#16#7002 with BUSY bit 1, to indicate that the enable job is still being processed. After about 1 minute RET_VAL delivers the value W#16#80A2 for about one CPU cycle. This indicates that the DP slave addressed is not responding. The DP slave remains disabled after this procedure. The BF LED of the associated DP master remains off during this procedure.

Note:
If the DP slave is later connected to the DP bus and is to be enabled, you must trigger SFC 12 again.

More information on the behavior of SFC 12 is available in the Online Help of STEP 7 or in the manual "System Software for S7-300/400 System and Standard Functions" in Entry ID: 1214574.