TwinCAT NC I – Axis interpolation in three dimensions

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. 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:

• techniques for sub-routines and jumps
• programmed loops
• zero offset shifts
• tool compensations
• tools
• M and H functions

 

3-D interpolation

The following geometries are supported by the interpreter:

• a straight line in space
• circles in all main planes
• circles in space
• helices with base circles in the main planes

 

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 jobs 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.

 

Minimum speed at the geometrical cross-over points

For many applications (laser, welding) it is essential not to go below a certain minimum speed when passing over geometrical cross-over points. The minimum speed can be set using parameters for this purpose.

 

Speed reduction at curves

TwinCAT NC I offers two 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.

 

“Look Ahead”

The “Look Ahead” works over all the data entered and connects neighbouring geometries as 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.

 

Geometric-dynamic smoothing with splines

Bezier splines can automatically be inserted to achieve the best possible geometric and dynamic smoothing at the transitions between segments.

 

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.

Technical data	TwinCAT NC I
PC hardware	standard PC/IPC hardware, no extras
Operating systems	Windows NT/2000/XP/Vista, Windows NT/XP Embedded, Windows CE
Real-time	Beckhoff real-time kernel as a component of TwinCAT
Run-time system	NC interpolation, including TwinCAT NC PTP and PLC
Number of axes	3 axes per group, 1 group per channel, max. 31 channels, auxiliary axes
Axis types	electrical servo-axes, stepper motor drives
Interpreter functions	subroutines and jumps, programmed loops, zero shifts, tool compensations, M and H functions, “delete distance to go”
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
Axis functions	online reconfiguration of axes in groups, path override, slave coupling to path axes
Programming	DIN 66025 programs for NC interpolation, access via function blocks for TwinCAT PLC according to IEC 61131-3
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	free choice of fieldbus: EtherCAT, PROFIBUS DP/MC, CANopen, DeviceNet, Interbus, SERCOS, Lightbus, Ethernet, PC hardware (printer port, COM port, USB), PC cards: generic memory DPRAM support
Connectivity	variable access via OPC, Beckhoff ADS OCX/DLL (Automation Device Specification)

Ordering information
TwinCAT NC I	licence for using the interpolation and PTP positioning software with integrated IEC 61131-3 TwinCAT PLC, contains programming software and run-time system