Technical data

11.8 Sending Control Commands to the DP Slave
Using the special HDB A-NR: 209, the "Global_Control" DP service can be
used to send various control commands to the DP slaves.
These Global_Control jobs can be used, for example, to synchronize the I/O
data from some or all of the connected DP slaves .
In general, the following rules apply for sending Global_Control jobs:
➣
A DP slave only accepts control commands from the master that
assigned parameters to it and configured it.
➣
By using the "group identifier" (see COM function DP slave parameter
assignment, Section 11.6.2) it is possible to control commands:
– to a particular DP slave (single)
– to certain groups of DP slaves (multicast), or
– to all connected DP slaves (broadcast)
Global_control jobs are not acknowledged on the L2 bus, i.e. the reception
of a global_control frame is not confirmed by the DP slaves .
At the handling block-user program level for the special HDB A-NR: 209
there is only a confirmation in the job acknowledgment field indicating that
the global_control frame was sent.
Distributed I/Os (DP) B89060/02
Volume 1 11 - 66