Siemens sinumerik 840D sl Function Manual page 961

Glossary
PLC program memory
SINUMERIK 840D: The PLC user program, the user data and the basic PLC program are
stored together in the PLC user memory.
PLC Programming
The PLC is programmed using the STEP 7 software. The STEP 7 programming software is
based on the WINDOWS standard operating system and contains the STEP 5 programming
functions with innovative enhancements.
Polar coordinates
A coordinate system, which defines the position of a point on a plane in terms of its distance
from the origin and the angle formed by the radius vector with a defined axis.
Polynomial interpolation
Polynomial interpolation enables a wide variety of curve characteristics to be generated,
such as straight line, parabolic, exponential functions (SINUMERIK 840D).
Positioning axis
Axis that performs an auxiliary movement on a machine tool (e.g., tool magazine, pallet
transport). Positioning axes are axes that do not interpolate with → path axes.
Pre-coincidence
Block change occurs already when the path distance approaches an amount equal to a
specifiable delta of the end position.
Program block
Program blocks contain the main program and subroutines of → part programs.
Programmable frames
Programmable → frames enable dynamic definition of new coordinate system output points
while the part program is being executed. A distinction is made between absolute definition
using a new frame and additive definition with reference to an existing starting point.
Programmable Logic Control
Programmable logic controllers (PLC) are electronic controls, the function of which is stored
as a program in the control unit. This means that the layout and wiring of the device do not
depend on the function of the control. The programmable logic controller has the same
structure as a computer; it consists of a CPU (central module) with memory, input/output
modules and an internal bus system. The peripherals and the programming language are
matched to the requirements of the control technology.
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Special functions: Appendix
Function Manual, 11/2006, 6FC5397-2BP10-2BA0