TwinCAT NC PTP – Point-to-point axis positioning
Position control with the PC
TwinCAT NC PTP includes axis positioning software (set value generation, position control), an integrated software PLC with NC interface, operating program for commissioning and an I/O connection to the axes through various fieldbuses. TwinCAT NC PTP replaces conventional positioning modules and NC controllers.
NC PTP software on the PC
The position controller is normally calculated on the PC processor and cyclically exchanges data via the fieldbus with drives and measurement systems.
The capacity of a PC allows axes to be moved in parallel with the PLC functionality. PC power means that some tens of axes can easily be positioned simultaneously.
System structure
Axes are structured into channels for PTP movement and for interpolated movements.
Axis structure
TwinCAT NC PTP uses variables to operate axes. Each axis has variables for encoder, drive and controller. The axis can be linked to I/O interfaces, and parameters can be set.
Axis functions
Axis functions such as
- start (various modes)
- stop
- new target position and velocity
- constant drive output
- set/call actual position
Axis types
- servo axes
- high/low speed axes
- stepper motor axes
- “low-cost” stepper motor axes
- encoder axes
- simulation axes
- DC drives
Position measurement systems
The position controller acquires the actual position through:
- incremental encoders
- absolute encoders
- digital interfaces to the drives
Drive interfaces
- analog
- EtherCAT
- SERCOS
- SSI
- Lightbus
- PROFIBUS DP/MC
- pulse train
Interfaces
- interfacing to all popular fieldbuses, in particular EtherCAT, Lightbus, SERCOS, PROFIBUS MC, synchron CAN
- Axis functions can be embedded into the IEC 61131-3 PLC system by means of function block libraries; the function blocks comply with the PLCopen standard.
- data interface to Windows NT/2000/XP/Vista/CE programs by means of open standards (OPC, Beckhoff ADS)
System operation
Positioning
Positioning is executed with a powerful, modern positioning algorithm in which profiles are generated with jerk limitation and with pre-control of speed and acceleration to minimise the following error.
Positioning facilities:
- Controller structures can be adjusted.
- P controller
- PID controller
- PID with speed pre-control
- PID with speed and acceleration pre-control
- override functions
Commissioning/servicing
The online menu allows important axis parameters such as
- target position,
- set speed,
- acceleration, jerk,
- reference speed,
- controller Kv factor,
to be set, and general axis functions such as
- start,
- stop/emergency stop,
- new target position with new speed,
to be called.
Special functions
- linear coupling (electrical gears)
- distance compensation
- online master/slave and slave/master conversion
- “flying saw” (diagonal saw)
- camming (support through TwinCAT Cam Design Tool)
- FIFO axes
- change over encoders/controllers
- external axis set value generator
Connection between NC software
and drive using drap and drop
Programming via IEC 61131-3 function blocks or standard PLCopen Motion Control libraries
| Technical data | TwinCAT NC PTP |
|---|---|
| PC hardware | standard PC/IPC hardware, no extras |
| Operating systems | Windows NT/2000/XP/Vista, Windows NT/XP Embedded, Windows CE (only run-time) |
| Real-time | Beckhoff real-time kernel as a component of TwinCAT |
| Run-time system | NC point-to-point (NC PTP) including TwinCAT PLC |
| Number of axes | up to 255 axes |
| Axis types | electrical and hydraulic servo drives, frequency converter drives, stepper motor drives, DC drives, switched drives |
| Cycle time | 50 µs upwards selectable (typically 1 ms) |
| Axis functions | standard axis functions: start/stop/reset/reference, speed override, destination override; special functions: master-slave cascading, electronic gearing, online distance compensation |
| Programming | performed using IEC 61131-3 function blocks in the TwinCAT PLC, convenient methods for axis commissioning |
| Debugging | online monitoring of all axis state variables such as actual/set value, enable, controller values, online axis tuning, forcing axis variables |
| Configuration | all axis parameters such as the measuring system, drive parameters and position controller can be conveniently configured |
| Remanence | remanent data, UPS-supported storage on hard disk |
| I/O system | free choice of fieldbus: EtherCAT, PROFIBUS DP/MC, CANopen, DeviceNet, Interbus, SERCOS, Lightbus, Ethernet |
| Connectivity | variable access via OPC, Beckhoff ADS OCX/DLL |
| Ordering information | |
|---|---|
| TwinCAT NC PTP | licence for using the PTP positioning software with integrated IEC 61131-3 TwinCAT PLC, contains programming software and run-time system |
| Options | |
|---|---|
| TwinCAT NC Camming | IEC 61131-3 software library for TwinCAT, implemented camshaft functionality (table coupling) |
| TwinCAT NC FIFO Axes | IEC 61131-3 software library for TwinCAT, permits specified FIFO set value generation |
| TwinCAT NC Flying Saw | IEC 61131-3 software library for TwinCAT, implements a “flying saw” |
| TwinCAT Cam Design Tool | graphical development tool for programming cams |
| TwinCAT Valve Diagram Editor | graphics-oriented editor for designing the characteristic curve of a hydraulic valve |