As opposed to motion commands, retriggering an MC_TouchProbe or MC_AbortTrigger instance does not result in the previous command being overwritten; instead, the new command is rejected by the FBs and no new command is sent. The retriggered FB instance indicates an FB-specific error and remains ACTIVE.
At the FB outputs "error" and "error_id", a signal is output for one PLC cycle with which retriggering can be detected. If either AXIS_REF or TRIGGER_REF has changed at the time of retriggering, this is indicated as an error at the aforementioned FB outputs and the command is also rejected.
The CommandAborted output can only be set if the command has been explicitly aborted by an MC_AbortTrigger. The identical measuring channel number and mode must then be used in TRIGGER_REF since a measuring command is exclusively identified by the matching of all parameters in TRIGGER_REF.
Contrary to the motion commands, a measurement command does not lead to a change in the axis status. As PLCopen does not specify in what states MC_TouchProbe is permissible, it is defined that this is permissible in all states except "ERROR_STOP" and "HOMING".
A separate state diagram is implemented for a measuring channel. The current state of the measuring channel is managed in “tp_state” in the AXIS_REF of the axis which was used to send the measuring command.
State diagram of the measuring channel
When, a maximum of as many measurement commands are possible as there are axes.
