How often can I call the system function SFC12 "D_ACT_DP" at the
SFC12 "D_ACT_DP" works asynchronously, i.e.
this system function executes a task spanning over several cycles.
In order to enable the execution of all necessary cycles, the
parameter "REQ" has to be set as long as the task is active. The
parameter "REQ" needs to stay on "TRUE", until the parameter "BUSY"
has reached the "FALSE" level again.
using the S7 300 CPUs with an internal DP interface; the SFC12
can be called up to four times at the same time. The SFC12 can be
called up to four times per DP rope (internal and external)
at the same time at the S7-400 CPUs.
When using the CP342-5 as a DP master, SFC12
cannot be used for the activation/deactivation.
Activating a DP-Slave might be costly in time. If you want to
abandon a running activation order, start the system function with
the same value for LADDR and MODE = 2. Repeat the call with MODE =
2 till the successful abort of the activation task is displayed
with RET_VAL. This procedure is only possible with the CPUs of the
S7-300 line. You cannot abandon the task with S7 400 CPUs.
More information about the SFC12 can be found in the manual
"SIMATIC System software for S7-300/400 System and Standard
functions" at EntryID: 1214574" and in the STEP 7 ONLINE Help
(Mark SFC block in the block container and press the F1 key).