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TwinCAT Software

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  TwinCAT Software

The Windows Control and Automation Technology

The Beckhoff TwinCAT software system turns almost any compatible PC into a real-time controller with a multi-PLC system, NC axis control, programming environment and operating station. TwinCAT replaces conventional PLC and NC/CNC controllers as well as operating devices with:

  • open, compatible PC hardware
  • embedded IEC 61131-3 software PLC, software NC and software CNC in Windows NT/2000/XP/Vista, Windows 7, NT/ XP Embedded, CE
  • programming and run-time systems optionally together on one PC or separated
  • connection to all common fieldbuses
  • PC interfaces support
  • data communication with user interfaces and other programs by means of open Microsoft standards (OPC, OCX, DLL, etc.)


TwinCAT architecture

TwinCAT consists of run-time systems that execute control programs in real-time and the development environments for programming, diagnostics and configuration. Any Windows programs, for instance visualisation programs or Office programs, can access TwinCAT data via Microsoft interfaces, or can execute commands.


A practically oriented software solution

TwinCAT offers a precise timebase in which programs are executed with the highest deterministic features, independently of other processor tasks. The real-time load on a PC is set with TwinCAT; defined operating behaviour is achieved in this way. TwinCAT indicates the system load for programs that are running. A load threshold can be set in order to assure a defined computing capacity for the operating programs as well as for Windows NT/2000/XP/Vista or Windows 7. If this threshold is exceeded, a system message is generated.


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:

  • IL (Instruction List),
  • LD (Ladder Diagram),
  • FBD/CFC (Function Block Diagram),
  • SFC (Sequential Function Chart) and
  • ST (Structured Text).

TwinCAT PLC running under 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. Under 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

  • locally,
  • via TCP/IP or
  • via the fieldbus (BXxxxx and BCxxxx).


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 turnaround 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:

  • monitoring,
  • powerflow (flow control),
  • break point,
  • sampling trace of PLC variables,
  • single step,
  • watchlist,
  • call hierarchy and
  • forcing of variables.

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:

  • positioning (set value generation and position control)
  • integrated PLC with NC interface
  • operating programs for commissioning purposes
  • I/O connection for axes via fieldbus

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 and acceleration.


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 with up to eight 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 expands TwinCAT NC I with classic CNC features: Up to 32 interpolating 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 or 32 path axes and 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:

  • velocity and acceleration control across blocks for optimum utilisation of axis dynamics and therefore higher achievable path velocities
  • high surface quality through smoothed dynamics and associated reduction of vibrational excitation of the machine
  • effective control of specified contour tolerances
  • path programming via splines with programmable spline type (Akima spline, B-spline) for reduction of NC blocks for free-form surfaces
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