Glossary · Motion control and drives
PLCopen motion control function blocks
Also known as: PLCopen motion blocks, MC function blocks
German: PLCopen Motion-Control-Funktionsbausteine
In IEC 61131-3 programming, PLCopen motion control function blocks are standardized function blocks, such as MC_Power, MC_Home, MC_MoveAbsolute and MC_GearIn, and a defined axis state machine, specified by PLCopen so that motion programs look the same across compliant controllers.
- Motion control
- Standards
In one sentence
PLCopen motion control function blocks are standardized IEC 61131-3 blocks and an axis state machine for vendor-neutral motion code.
Example
The PLC program enables an axis with MC_Power, homes it with MC_Home and then moves it with MC_MoveAbsolute.
How it applies
- Engineering: The blocks share common inputs and outputs (Execute, Done, Busy, Error, ErrorID) and act on an axis reference. The axis state machine (for example Disabled, Standstill, Homing, Discrete Motion, Synchronized Motion, ErrorStop) defines which commands are valid when.
- Commissioning: Vendors implement the specification with extensions; code portability is limited to the standard blocks.
- Operation: Error handling relies on the state machine: an axis in ErrorStop must be reset before it moves again.
- Documentation: Use the state machine as the backbone of software documentation and describe machine behavior with the same states. Keep block names in their original spelling as code, not translated.
PLCopen blocks vs. vendor motion libraries
Vendor libraries often cover more functions and use their own names. PLCopen blocks give a common base, which makes training material and code reviews portable between platforms.