Follow the path with the PC
The TwinCAT NC Interpolation (NC I) is the NC system for interpolated path movements. TwinCAT NC I offers 3-D interpolation (interpreter, set point generation, position controller), an integrated PLC with an NC interface and an I/O connection for axes via the fieldbus. All well known Fieldbus systems and programming standards in the CNC world, such as DIN 66025, are supported. TwinCAT NC I delivers open PC solutions for standard axial components and CNC controls. TwinCAT NC I uses the power of the PC and allows axis regulation under Windows NT/2000/XP/Vista/CE or Windows 7. Hardware modules are simulated in the software, and are thus superfluous.
TwinCAT NC I – interpreter
The syntax which is laid down in DIN 66025 is a reliable descriptive language for machine sequences. There is also an additional extension to the DIN syntax with a number of useful functions:
The following geometries are supported by the interpreter:
TwinCAT NC I – operating interface
An operating interface integrated into the TwinCAT System Manager provides information on all set and actual values and on the physical and logical state of the interpolation channels and interpolation axes. The NC structure and many NC parameters are also set using the System Manager.
Online changes of configuration of the axes
Individual PTP axes can be collected flexibly, when the axes are stationary, into new interpolation groups, after which they can be reconfigured as PTP axes. In this way all PTP characteristics such as reference run, tool change, etc. can be used.
PLC blocks for interpolation
In order to create a simple interface for axis interpolation, PLC blocks which can create positioning commands for the interpolation channel, using easily understood descriptions organised as tables are available.
TwinCAT NC I – pathway dynamics
A rate-of-change limited profile, which at any moment describes the acceleration, speed and position on the path as well as the associated transformed Cartesian axis values. The maximum allowed dynamic limiting values can be changed at any time in the NC program.
TwinCAT NC I – path override
TwinCAT NC I possesses a speed override function which can synchronously work on all of the axes.
Speed reduction at curves
TwinCAT NC I offers different reduction methods for reducing the speed on neighbouring geometrical cross-over points. The parameter for this speed reduction can be changed in the NC program.
TwinCAT NC I axes
For each channel three path axes (X, Y, Z) can be used. In addition, five further auxiliary axes can be integrated into the channel. These are interpolated with the path, i.e. they start with the path segment and arrive in the target position with the path segment.
The “Look Ahead” function calculates the maximum possible path velocity at segment transitions. It can take into account all entries in the NC core and connects neighbouring geometries so far as this is possible.
Slave coupling on the path axes
A master/slave coupling on a path axis is possible, independently of which slave type is involved.
Various options are available in order to achieve optimum geometrical and dynamic smoothing at segment transitions (e.g. Bezier smoothing). In this way, the path velocity can be kept constant at segment transitions if the boundary conditions are suitable. This is particularly important for pick-and-place tasks and manipulations (e.g. laser welding).
Diagnostic and optimisation possibilities
All machine state variables can be extracted and displayed for diagnostic and analysis purposes. An ideal tool in this respect is TwinCAT ScopeView, which allows all internal and external variables to be recorded. These variables include path values (set and actual values) such as path speed, path acceleration, tangential and orthogonal path error as well as Cartesian values such as position, speed, following error, etc.
TwinCAT Scope 2
|PC hardware||standard PC/IPC hardware, no extras|
|Operating systems||version-dependent: Windows NT/2000/XP/Vista, Windows 7, Windows NT/XP Embedded, Windows CE (only runtime)|
|Real-time||Beckhoff real-time kernel as a component of TwinCAT|
|Runtime system||NC interpolation, including TwinCAT NC PTP and PLC|
|Number of axes||max. 3 axes and up to 5 auxiliary axes per group, 1 group per channel, max. 31 channels|
|Axis types||electrical servo-axes, stepper motor drives|
|Interpreter functions||subroutines and jumps, programmable loops, zero shifts, tool compensations, M and H functions|
|Geometry functions||straight lines and circular paths in 3-D space, circular paths in all main planes, helixes with base circles in all main planes, linear, circular, helical interpola tion in the main planes and freely definable planes, Bezier splines, look-ahead function|
|Axis functions||online reconfiguration of axes in groups, path override, slave coupling to path axes, auxiliary axes, axis error and sag compensation, measuring functions|
|Programming||DIN 66025 programs for NC interpolation, access via function blocks for TwinCAT PLC according to IEC 61131-3|
|Operation||automatic operation, manual operation (jog/inching), single block operation, referencing, handwheel operation (motion/superposition)|
|Debugging||online monitoring in the TwinCAT System Manager with the following displays: present set/actual positions (following errors of all axes), NC program line presently being executed, NC program line presently being interpreted, channel status|
|I/O system||EtherCAT, Lightbus, PROFIBUS DP/MC, Interbus, CANopen, DeviceNet, SERCOS, Ethernet|
|Connectivity||variable access via OPC, Beckhoff ADS OCX/DLL (Automation Device Specification)|
|TX1260||licence for using the interpolation and PTP positioning software with integrated IEC 61131-3 TwinCAT PLC, contains programming software and runtime system|
|TS511x||PLC library for the implementation of different kinematic transformations for TwinCAT PTP or TwinCAT NC I|