Siemens SINUMERIK 808D ADVANCED Programming And Operating Manual page 227

Further notes
If the straight line that was generated with close contour is linked to the start element of the contour with a radius or chamfer,
the radius or chamfer must be specified explicitly as follows:
● Close contour, input key, enter radius/chamfer, accept element. The result then corresponds exactly to what would occur
if the closing element were to be entered with the radius or chamfer.
Close contour can only be used for entering contour elements in polar coordinates if the starting point of the contour was
set to polar and the same pole is still valid when the contour is closed.
Input switchover: Cartesian/polar
The following contour elements can be entered optionally in polar coordinates only after a pole has been defined, whether
this was done at the outset or later in the process:
● Circular arcs,
● Straight lines (horizontal, vertical, any direction)
To switchover between Cartesian and polar coordinates, additional toggle fields are displayed in the programming windows
for the contour elements of oblique lines and circular arcs.
A toggle field is not displayed if no pole exists. Input fields and display fields are then only available for Cartesian values.
Absolute/incremental input
Absolute and incremental polar coordinates can be input for "polar/Cartesian". The input fields and display fields are labeled
ink and abs.
Absolute polar coordinates are defined by an absolute distance to the pole that is always positive and an angle in the range
of 0° ... +/- 360°. When absolute dimensions are specified, the angular reference is based on a horizontal axis of the working
plane, e.g. X axis with G17. The positive direction of rotation runs counter-clockwise.
If there are several input poles, the definitive pole is always the last pole before the input or edited element.
Incremental polar coordinates relate to both the definitive pole and the end point of the preceding element.
For an incremental input, the absolute distance to the pole is calculated using the absolute distance from the end point of the
preceding element to the pole plus the length increment that was entered.
The increment can be positive or negative.
The absolute angle is calculated accordingly using the absolute polar angle of the preceding element plus the angular
increment. Here it is not necessary for the preceding element to have been entered as polar.
In contour programming, the contour calculator converts the Cartesian coordinates of the preceding end point using the
definitive pole into polar coordinates. This also applies if the preceding element has been given in polar coordinates, since
this could relate to another pole if a pole has been inserted in the meantime.
Programming and Operating Manual (Turning)
6FC5398-5DP10-0BA2, 06/2015
This softkey allows you to specify a pole and can only be entered in absolute Cartesian coordi-
nates. This softkey is also present in the starting point screen. This enables the pole to be entered
at the start of a contour, so that the first contour element can be entered in polar coordinates.
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