In this state, the system is characterized by the following properties:
- The vision system has received a command to begin the execution of an individual job (measuring, inspection, identifying, …), e.g. by a call to the StartSingleJob method on the server.
- The vision system collects sensor data (i.e. acquiring single or multiple images, possibly awaiting triggers, often in hardware).
- If data acquisition is a “multi-stage-process” (interaction with other devices) this may be modelled with a VisionStepModelType SubStateMachine (all states allow for this, but this is the most typical application, therefore we emphasize it here).
- The vision system may indicate to the client by an AcquisitionDone event that acquisition has been finished, e.g. as a signal that the part can be removed from the camera’s field of view, either by moving the part or he camera.
- The vision system carries out the processing of the acquired data at least so far that the internal resources are available to transition into state Ready to accept the next start command.
- Results can be pulled from the internal result-store by the methods detailed in Section 7.5 (depending on the capabilities of the system).
Note that the above description illustrates a typical behavior. The vision system is, however, in no way obliged to perform any particular operation – like image acquisition or processing – in this state. It can do completely different things or nothing at all before returning to Ready state. The point is rather that the difference between SingleExecution state and Ready state lies in the availability of the required resources for starting a job.
If an error is detected which suspends normal operation, the system will change to state Error in the VisionStateMachine.
This state can be left in the following ways:
- into the Ready state by an automatic transition when the required resources are available. The system shall trigger a Ready event in this case. Note that this is in no way related to the vision system completing an image acquisition or evaluation and/or producing a result.
- Into the Ready state by the methods Stop and Abort, see Section 8.3.2.4 for details.
- Into the Preoperational state of the VisionStateMachine by a Reset method call.
- Into the Halted state of the VisionStateMachine by a Halt method call.
- Into the Error state of the VisionStateMachine by an internal error.
All method-triggered transitions can also occur automatically upon an internal decision of the system.
This state can be a composite state with an optional VisionStepModelStateMachineType SubStateMachine.