TwinCAT NC Axes

Axis control loop

The axis control loop consists of velocity pre-control, position controller and a controller limitation.

Slave axes

Axes whose set values (position, velocity, acceleration) are generated in functional dependency on the set values of other axes (master axes, virtual axes, slave axes, simulation axes) - on their set position values - are called slave axes. Apart from the coupling and uncoupling, these axes do not generally have any functionality of their own (they do not have start or stop functions) and operate under linear path control in synchronization with the master axis (which itself can in turn be a slave axis).

When a master axis (which is to become a slave axis) is coupled to another master axis, the slave axis retains its own position control.

The slave axes of NCI groups make up a special class

High/low speed axes

The TwinCAT high speed/low speed axis type (two speed) allow the positioning of a high speed/low speed axis. Such a high speed/ low speed axis can be physically made up of a motor with two speeds (switching of the pole pair numbers), or alternatively by a motor that can be driven at two speeds with the help of a frequency converter.

"Low Cost" stepper motor axis with digital control (24V / 2A)

The basic version of the 'low cost stepper motor axis' is operated without physical encoder (hence simulation encoder). This means that there is no actual physical feedback between set values and actual values, and therefore the axis is not operated with closed-loop control, but only with open-loop control. It is assumed that there is no slippage in the drive, and that the axis can accurately follow the specified step pattern (set value profile). Notwithstanding this constraint imposed for cost reasons, the stepper motor axis can be referenced physically, since the simulation encoder is implemented as an incremental encoder and supports virtually all features.

Functional overview of the individual axis types