Siemens SINUMERIK 828D Function Manual page 882

P3: Basic PLC Program for SINUMERIK 840D sl
13.8 Structure and functions of the basic program
• Control of spindle (FC 18),
• Read/write variables (FB 2, FB 3).
Note
The following note will later help you to check and diagnose a function call (FCs, FBs of
basic program). These are FCs and FBs, which are controlled by a trigger signal (e.g. via
parameter Req, Start, etc.), and which supply an execution acknowledgment as an output
parameter (e.g. via parameter Done, NDR, Error, etc.). A variable compiled of other
signals, which produce the trigger for the function call should be set. Start conditions may
be reset only as a function of the states of parameters Done, NDR and Error.
This control mechanism may be positioned in front of or behind the function call. If the
mechanism is placed after the call, the output variables can be defined as local variables
(advantage: Reduction of global variables, flags, data variables and time­related
advantages over data variables).
The trigger parameter must be a global variable (e.g. flag, data variable).
In OB 100, jobs still activated by the user program (Parameter Req,
Start, etc.:= TRUE) must be set to zero at the named parameters. A POWER OFF/ON
could result in a state in which jobs are still active.
Concurrent axes
The distinguishing features of concurrent axes are as follows:
• They must be defined as such via the NC machine data.
• They can be traversed either from the PLC or from the NC by means of the JOG keys,
• Starting from the PLC is possible in the NC operating modes MDI and AUTOMATIK via FC,
• The start is independent of NC block boundaries.
Function calls are available for positioning axes, indexing axes and spindles (FC 18).
Figure 13-13 FC 18 input/output parameters
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Function Manual, 09/2011, 6FC5397-0BP40-2BA0
Basic Functions