State Diagram
Motion State Diagrams
This manual is adopted from the PLCopen for Motion Control specification at www.plcopen.org, and includes additional information for functionality with Yaskawa and other components.
Model
The PLCopen Plus Function Block firmware library is designed for the purpose of controlling motion via the language elements consistent with those defined in the IEC 61131-3 standard. It provides a set of command oriented function blocks that have a reference to the axis, e.g. the abstract data type ‘Axis’, which offers flexibility, ease of use and reusability.
The Single Axis State Diagram
The state diagram shown defines the behavior of the axis at a high level when motion control function blocks are "simultaneously" activated. This combination of motion profiles is useful in building a more complicated profile or to treat exceptions within a program.
The basic rule is that motion commands are always taken sequentially. These commands act on the axis' state diagram. The axis is always in one of the following defined states:
- Standstill (no movement)
- Homing (movement to reference position)
- Discrete Motion (movement towards target position)
- Continuous Motion (jogging)
- Synchronized Motion (synchronized movement of master and slave)
- Stopping (axis is stopped)
- ErrorStop (axis error occurred)
- Disable
Any motion command is a transition that changes the state of the axis and, as a consequence, modifies the way the current motion is computed. A normal procedure would start in In this state, the power can be switched on per axis (via the command). Also, one can access the Homing state (via the issue of Home command per axis), which after normal completion returns to Standstill. From here, one can transfer an axis to either Discrete Motion or Continuous Motion. Via the Stopping state, one can return to Standstill. ErrorStop is a state to which the axis transfers in case of an error. Via a Reset command, one can return to Standstill, from which the machine can be moved to an operational state again. Please note that the states define the functionality of the Function Blocks. Disable.MC_PoweraIf the last executed block was MC_StepLimitSwitch, then MC_FinishHoming needs to be executed to return to Standstill.
The diagram is focused on the states of a single axis. The multiple axis function blocks such as MC_Phasing, MC_CamIn and MC_GearIn change the state whereas these axis can have specific states. Connecting a slave axis to a master axis has no influence on the master axis.
The following administrative function blocks do not have any effect on the State Diagram: MC_ReadStatus; MC_ReadAxisError; MC_ReadParameter; MC_ReadBoolParameter; MC_WriteParameter; MC_WriteBoolParameter; MC_ReadActualPosition and MC_CamTableSelect.
Interpolation / Group State Diagram
Please see Group State Diagram