PLC and Motion Control on the PC

TwinCAT I/O – universal I/O interface for all common fieldbuses

Many PC fieldbus cards from various manufacturers are supported. It is possible to operate more than one fieldbus card per PC. Master and slave functionality is supported, depending on the selected fieldbus card. The fieldbus cards can be configured and diagnosed conveniently via the TwinCAT System Manager. TwinCAT I/O includes the TwinCAT real-time system for operating the fieldbuses and a DLL interface to application programs.


TwinCAT PLC – the central pillar of automation software

Conceived as a pure software PLC, TwinCAT PLC allows up to four virtual “PLC CPUs”, each running up to four user tasks, on one PC. The PLC program can be written in one or more of the languages provided for in the IEC 61131-3 standard:

TwinCAT PLC running ander the Windows NT/2000/XP/Vista operating systems includes both the programming environment and the run-time system, so that an additional programming device is not required. ander the CE operating system and the embedded operating systems for the series BX and BC controllers, only TwinCAT run-time is available. Program modifications are implemented via network-capable powerful communication with the run-time system. Programming can be done


IEC 61131-3 – advanced programming standard for all Beckhoff controllers

The TwinCAT PLC is programmed in accordance with IEC 61131-3 independently of the manufacturer. TwinCAT supports all the IEC 61131-3 programming languages with convenient editors and a fast, effective compiler, so that the development cycle for the creation even of large PLC programs of several megabytes can be short. Incremental compilation prevents long turnaroand times. Only genuinely new sections are compiled. Powerful editor features, such as “autoformat”, “autodeclare” or “find” and “replace” enable fast programming. For all programming languages, the project comparison function facilitates differences to be identified and accepted if appropriate. If a project (comments, directories, etc.) is to be translated into a language other than the original language, all terms can be exported into a table, translated and re-imported. If a team is dealing with the development, all objects (blocks, data types, lists) can be managed within a source code management tool via the TwinCAT Engineering Interface. This enables changes to be traced back and differences between individual versions to be displayed.

The concept of the “instantiation” of function blocks, in which each instance is associated with its own data, leads naturally to object-oriented and structured programming styles. All common data types specified in IEC 61131-3 are supported. Multi-dimensional fields and structures are possible, as are enumeration and subrange types.

TwinCAT PLC is certified for the languages IL and ST (base level). The online change function can be used for code and/or data modifications while the PLC is running, providing maximum data retention. Source code can be stored in the target system (except for BCxxxx series controllers). The criteria analysis function is very helpful for the detection of process errors.

Code can very easily be reused via the convenient library manager. For know-how protection, multi-stage password protection can be applied to programs and libraries.


Many target platforms – one tool

The PLC programs created with TwinCAT PLC can be executed on a number of target platforms. Apart from Industrial PCs and the Embedded PCs, the PLC project can also be loaded into the BC and BX series fieldbus controllers from Beckhoff. Program development and debugging proceed in the same working environment, regardless of which unit is executing the program.


Extensive supplementary libraries

As an extension to the blocks defined by the IEC language standard, Beckhoff offers a wide range of supplementary libraries for the execution of tasks typical in automation technology: e.g. libraries for controlling electrical and hydraulic axes via TwinCAT NC, serial communication libraries, system libraries for message outputs, write/read files, control technology blocks, etc.


Helpful practice tools

Extensive faultfinding functions in TwinCAT PLC facilitate the solution of problems either on site or via remote maintenance. For this purpose, the PLC programming environment in TwinCAT offers:

In addition, the TwinCAT ScopeView (a software oscilloscope) can be used to record one or several variables simultaneously.


TwinCAT NC – Motion Control on the PC

A software NC consists of:

With TwinCAT NC, the position controller is calculated on the PC processor as standard. It exchanges data cyclically with drives and measurement systems via the fieldbus.


Central NC positioning on the PC

The computing capacity of a PC enables axis motion simultaneously with the PLC, whereby the position controller is usually calculated on the PC: The computing capacity of a PC enables many axes to be positioned simultaneously.

TwinCAT enables a PC to process the operating programs, the PLC and the NC at the same time. The division of the system load is supported by TwinCAT with appropriate functions.


Analytical path calculation

The algorithms that TwinCAT NC/NC I/CNC uses to control axes take account of the dynamic parameters of the axis: speed, acceleration and jerk. In this way, the axes are moved at any time within the limits of what is dynamically possible, and are precisely analytically coordinated. A range of different regulation algorithms are available in order to reduce the deviations from the ideal trajectory that will occur in practice.


Individual or joint

Based on the normal methods for positioning an individual electrical axis, moving from its starting point to its destination (point-to-point positioning), TwinCAT NC also allows the coordinated movement of a number of axes in multi-stage master-slave operation (e.g. gearing functions or cam plates) to be executed. TwinCAT NC I further allows the interpolated path sequencing described in accordance with DIN 66025 to be carried out involving up to three axes.


Software PLC included

TwinCAT combines software NC and software PLC to form a powerful controller. The communication between the two packages is a pure software/software channel with minimum delay times. The NC functionalities are called from the PLC program via standardised, PLCopen-certified function blocks.

Axis movements can be simulated without hardware; the actual value is instructed to ideally track the set value, and the complete machine flow is checked. TwinCAT ScopeView is helpful for commissioning and maintenance. It records all axis variables such as position, speed, acceleration and jerk.


Convenient commissioning

Commissioning is simplified significantly by the configuration and diagnostic dialogs offered in the TwinCAT System Manager. For each axis, all main data are displayed at a glance. The axes can be moved via function keys. Special functions such as couplings, cam plates or distance compensation can be triggered and observed via the System Manager. A convenient dialog enables the dynamic parameters of an axis to be determined.


TwinCAT NC I – axis interpolation in three dimensions

TwinCAT NC I (interpolation) is the NC system for linear and circular interpolated path movements of axis groups each involving two or three drives. The system includes interpreter, set value generation and position controller. PLC functionality is integrated, as is the connection of the axes with the fieldbus.

The interpreter interprets the code described in DIN 66025. Comprehensive PLC libraries enable interaction between NC and PLC. NC programs, for example, can be loaded directly from the PLC program into the interpreter. As an alternative to DIN 66025, the path interpolation via the TcPlcInterpolation library can take place directly from the PLC. In this case, the geometry and help functions (e.g. M functions) are written to a table in the PLC and transferred to the NC core. This procedure is particularly suitable for flexible movements, e.g. in pick-and-place applications.


TwinCAT CNC – the software CNC for toughest requirements

TwinCAT CNC offers CNC features: Up to 32 interpolating path axes and comprehensive coordinate and kinematic transformations are possible. Parts programming is carried out according to DIN 66025 using high-level language extensions. TwinCAT CNC can operate with up to 64 axes/controlled spindles that can be distributed across up to twelve CNC channels. In a CNC channel, up to 32 axes can be interpolated simultaneously, enabling even the most difficult motion tasks to be solved.

HSC technology (high-speed cutting)

Advanced HSC cutting technology requires CNC control technology with optimised solutions for Motion Control in order to achieve optimum results in terms of processing time while at the same time offering maximum accuracy and workpiece surface quality.

The TwinCAT CNC HSC pack offers the following options: