Enable the host application to trigger "application triggered" assembly data indepenedent of each other

Assembly instances that are part of an "Application triggered" connection typically trigger a process data frame on the network as soon as updated assembly data is available (host application writes new data into the DPM). In case more than one "application triggered" connection is running, the host application does not want to trigger frames for both connections at the same time. Therefore, the host application needs to be able to choose what assembly data is updated in the DPM to indicate to the netX firmware what connection shall trigger a frame.