Siemens SINUMERIK 840D sl Function Manual page 1103

Contour monitoring
The following error is monitored within a definable tolerance band as a measure of contour
accuracy. An unacceptably high following error can cause the drive to become overloaded,
for example. In such cases, an alarm is output and the axes are stopped.
Coordinate system
See → Machine coordinate system, → Workpiece coordinate system
CPU
Central processing unit, see → PLC
C-Spline
The C-Spline is the most well-known and widely used spline. The transitions at the
interpolation points are continuous, both tangentially and in terms of curvature. 3rd order
polynomials are used.
Curvature
The curvature k of a contour is the inverse of radius r of the nestling circle in a contour point
(k = 1/r).
Cycles
Protected subroutines for execution of repetitive machining operations on the → workpiece.
Data block
1. Data unit of the → PLC that → HIGHSTEP programs can access.
2. Data unit of the → NC: Data modules contain data definitions for global user data. These
Data word
Two-byte data unit within a → data block.
Diagnosis
1. Operating area of the control.
2. The control has both a self-diagnostics program as well as test functions for servicing
Extended Functions
Function Manual, 09/2009, 6FC5397-1BP20-0BA0
data can be initialized directly when they are defined.
purposes: status, alarm, and service displays
Glossary
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