PCIN data transfer programPCIN is an auxiliary program for sending and receiving CNC user data (e.g. part programs,tool offsets, etc.) via a serial interface. The PCIN program can run in MS-DOS on standardindustrial PCs.Peripheral moduleI/O modules represent the link between the CPU and the process.I/O modules are:● → Digital input/output modules● → Analog input/output modules● → Simulator modulesPLCProgrammable Logic Controller: → Programmable logic controller. Component of → NC:Programmable control for processing the control logic of the machine tool.PLC program memorySINUMERIK 840D sl: The PLC user program, the user data and the basic PLC program arestored together in the PLC user memory.PLC programmingThe PLC is programmed using the STEP 7 software. The STEP 7 programming software isbased on the WINDOWS standard operating system and contains the STEP 5 programmingfunctions with innovative enhancements.Polar coordinatesA coordinate system which defines the position of a point on a plane in terms of its distancefrom the origin and the angle formed by the radius vector with a defined axis.Polynomial interpolationPolynomial interpolation enables a wide variety of curve characteristics to be generated, suchas straight line, parabolic, exponential functions (SINUMERIK 840D sl).Positioning axisAxis that performs an auxiliary motion on a machine tool (e.g. tool magazine, pallet transport).Positioning axes are axes that do not interpolate with → path axes.GlossarySpecial functions848 Function Manual, 01/2015, 6FC5397-2BP40-5BA2