Siemens SIMATIC S5 Manual page 125

Executing Machining Programs
. . ,corresponds to a tool length offset of 80 mm forwards.
When any positioning movement is carried out, the new tool tip is brought to the specified target
position. This also applies to the execution of machining programs. If mode 15 is called again,
the offset is replaced by a new value.
The mode "tool length offset" requires valid machine data, A reference point is not necessary, A
value within the limits of +/-100 m (+/- 10000 inches or +/-100000 degrees) can be entered for
the tool length. Values outside these limits lead to termination of the program and to the error
message "illegal dist. spec. ".
The value displayed as the actual position following a tool offset is the position at which the tip of
the tool is located. Following a tool offset, even if a software limit switch is tripped, the actual
value (tool tip) must not exceed the limits of+ /-100 m (+ /-1~ inch=, + /-100ooo d~r=$.
This is checked when the tool offset is executed. If this condition is not met, the tool offset is not
accepted and the error message "traversing range exceeded" is set.
Example
A drilling program was written assuming that the drill is 100 mm long. The reference edge of the
chuck is position 50 when retracted. Enabling conditions were generated at this position for the
equipment, i.e. the chuck must always return to this retracted position. The target position of the
drill tip when operating is 200.
Implementation
BA15; 100 mm;
In the parameter for mode 15, only the actual length of the drill is entered when a drill is
changed, This means that the required depth is always achieved.
Before the drill is retracted, the offset is cancelled so that the chuck returns to the basic position.
In the program, you must, of course, make sure that the individual jobs are only sent when the
axis status is "finished".
Note
The detection of the software limit switch depends on the internal position setpoint.
The axis begins to brake when the reference edge of the tool holder passes a soft-
ware limit switch. Depending on the tool length offset, the tip of the tool may be
well outside the selected traversing range.
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