This page defines the main terms used across the manual.
An axis PLC is PLC logic attached directly to one axis as part of the motion configuration. Use it for axis-local logic such as local interlocks, setpoint conditioning, or small axis-specific sequences.
A best-practice example is a public, reusable example under
examples/PSI/best_practice/. These examples should be self-contained and are
the preferred examples to reference from the manual.
A component is a reusable hardware or function configuration block, typically
applied with applyComponent.cmd. Components are commonly used to configure
motors, encoders, and related EtherCAT-side settings.
Data storage is the buffered sample storage facility used for collecting values over time and optionally pushing them to EPICS/asyn.
A global PLC variable is shared across PLCs. Use it when several PLCs or EPICS
records need to access the same value.
Legacy motion refers to the older classic motion configuration flow based on
.ax, .vax, and .sax files and the related classic startup commands.
Master-less mode means running with MASTER_ID=-1, without an EtherCAT master.
This is also called non-EtherCAT mode in some pages.
Note:
The directory name masterless may still appear in example paths. In prose, the
preferred term is master-less.
A PLC in ecmccfg is deterministic logic executed in the ecmc cycle. Use a
normal PLC for shared logic, coordination across multiple axes, state handling,
I/O logic, and reusable control sequences.
A plugin is an optional runtime extension loaded into ecmc for functionality that is not part of the core axis/PLC setup.
A static PLC variable belongs to one PLC instance. It keeps its value between
PLC scans and is the normal choice for PLC-local state.
A virtual axis is an axis without a physical drive or encoder interface. It is typically used for coordination, synchronization, or higher-level motion logic.