P3: Basic PLC Program for SINUMERIK 840D sl
13.8 Structure and functions of the basic program
Basic Functions
Function Manual, 09/2011, 6FC5397-0BP40-2BA0
881
NCK → PLC signals
The signals sent by the NCK to the PLC are divided into the following groups:
• Status signals from the NCK, channels, axes and spindles
• Modification signals of the auxiliary functions
• Values of the auxiliary functions
• Values of the G functions
Status signals:
The status signals from the NCK, channels, axes, and spindles are reset.
Auxiliary-function modification signals:
Auxiliary-function modification signals are also reset.
Auxiliary-function values:
Auxiliary-function values are retained so that it is possible to trace the last functions triggered by the NCK.
G-function values:
G function values are reset (i.e. initialized with the value 0 respectively).
PLC → NCK signals
The signals sent by the PLC to the NCK are divided into control signals and tasks that are transferred by FCs to
the NCK.
Control signals:
The control signals from the PLC to the NCK are frozen; cyclic updating by the basic program is suspended.
Jobs from PLC to NCK:
The FCs and FBs, which are used to pass jobs to the NCK, must no longer be processed by the PLC user
program, as this could lead to incorrect checkback signals. During powerup of the control, a job (e.g. read NCK
data) must not be activated in the user program until the NCK CPU ready signal is set.
13.8.7 Functions of the basic program called from the user program
General
In addition to the modules of the basic program, which are called at the start of OBs 1, 40 and 100, functions are
also provided, which have to be called and supplied with parameters at a suitable point in the user program.
These functions can be used, for example, to pass the following jobs from the PLC to the NCK:
• Traversing concurrent axes (FC 18)
• Start asynchronous subprograms (ASUBs) (FC 9),
• Selecting NC programs (FB 4)
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