Siemens S7-1200 Two-Axis Motion Control Training Kit

Linear interpolation

The PLC performs coordinated motion between two or more axes according to the set start point and end point, controlling each axis to move synchronously in proportion to produce a linear trajectory.

Circular interpolation

Given the center, radius, and direction, multiple axes work together to produce a circular trajectory.

Both belong to trajectory interpolation functions in motion control. The S7-1200 implements them through technology object motion control, without the need for an external motion controller.

Limitations and significance

The S7-1200 interpolation only supports two-dimensional planes and does not support three-dimensional interpolation. The calculation cycle is affected by the PLC scan cycle, and its capability is limited in high-speed and high-precision scenarios. It is suitable for trajectory equipment at low-to-medium speeds. This helps engineers distinguish application boundaries and know when to select the S7-1200 and when a dedicated motion controller is needed.

Practical production value

It improves product forming consistency, as the trajectory is exactly the same every time. It reduces the complexity of mechanical structures by eliminating the need for cams and profiling mechanisms to achieve curved motion, relying on software trajectories instead. It also facilitates process modification: changing coordinate parameters can replace the machining contour without modifying the hardware mechanics.

Process application significance

Achieve continuous planar trajectory machining. Equipment needs to produce diagonal lines, arcs, and fillet contours, such as cutting machines, dispensing machines, engraving machines, and transfer profiling mechanisms. Single-axis jogging can only move horizontally or vertically, while interpolation can synthesize diagonal lines and arcs to complete continuous contour motion.

Multi-axis synchronization and coordination. The interpolation algorithm automatically distributes speed pulses to each axis, ensuring that the positional relationship between axes strictly conforms to the trajectory during motion. It prevents one axis from finishing while another is still running, thereby avoiding trajectory deviation.

By using trigonometric functions and position calculation logic, process instructions can be called directly, and coordinate parameters can be entered to output the trajectory. This reduces programming workload and minimizes errors caused by manual calculation.

Ensure smooth motion. Interpolation performs speed planning, with continuous acceleration and deceleration. There are no sudden starts or stops at corners and arcs, reducing mechanical shock, protecting servo motors, lead screws, and guide rails, and minimizing mechanical vibration.