Siemens SINUMERIK 840D sl Function Manual page 992

Brief description
Event-driven signal exchange PLC → NCK
An "eventdriven signal exchange PLC → NCK" takes place whenever the PLC passes a
request to the NCK (e.g., traversal of an auxiliary axis). In this case, the data transfer is also
controlled by acknowledgment. When performed from the user program, this type of signal
exchange is triggered using a function block (FB) or function call (FC).
The associated FBs (Function Blocks) and FCs (Function Calls) are supplied together with
the basic program.
Messages
User messages are acquired and conditioned by the basic program. A defined bit field is
used to transfer the message signals to the basic program. The signals are evaluated there
and entered in the PLC diagnostics buffer on the occurrence of the message events. If a
control unit is present, the messages are displayed on the operator interface.
Note
The function of the machine is largely determined by the PLC program. Every PLC program
in the working memory can be edited with the programming device.
8
Basic logic functions: PLC Basic program powerline (P3 pl)
Function Manual, 11/2006, 6FC5397-0BP10-2BA0