Group State Diagram

The group state diagram describes the commanded state of the group of axes. It is on top of the single axis state diagram PLCopen. While axes are in a group state, the single axis state diagram is also active per axis. Therefore interdependencies between the two types of state diagrams exist.

GroupDisabled is the initial state at power up where a group can be created. Issuing MC_GroupEnable leaves this state.

The next state is GroupStandby. In this state the group is enabled and no Function Block has control on one of the axes in the group. In this state the group can additionally be altered and homed if needed (State GroupHoming).

In the state GroupHoming a homing sequence can be defined for a group of axis. This can be applicable due to the mechanical constraints of multiple motors. For example in an mechanical construct looking like the letter “I“ with two motor mechanically coupled via one band or belt moving over the form of the letter I, need to be homed differently.

If a Function Block has control on (one of the axis of) the group, the state changes to GroupMoving.

GroupStopping is a special state that deals with the MC_GroupStop command, which automatically tranfers to the state GroupStandby as soon as Done = SET and Execute = FALSE in MC_GroupStop.

In case an error arises (in one of the axis) the state changes to GroupErrorStop, which can only be left via issuing MC_ResetGroup.

Explanations

Group motion commands will always lead to a Synchronized Motion state in the single axis state diagram. In case of a GroupStandby all axes of the group are also in single axis state StandStill.

A GroupErrorStop will not lead to ErrorStops of the grouped axes as the error may only affect the group. In case of a single axis ErrorStop the Group will also change to GroupErrorStop as the single error effects the group.

The group state diagram reflects the state of the group and the issued Function Blocks.

The group state diagram