Examples - Interaction

 

The VesselControlSystem

The purpose of this very simple example is to show how a cluster of synchronously interacting processes is specified. The example is complete and executable code can be generated for this CIP model.

External Processes
The vessel control system is used to add defined portions of a liquid to a technical production process.

A vessel is equipped with two discrete level sensors detecting when the vessel becomes full or empty. Two valves, which can be opened and closed by the system, serve to fill and empty the vessel. Two radio-buttons are used to activate and deactivate the system. A green and a red lamp serve to indicate the system activity.

Functional Requirements
Pushing the On-button activates the system to add liquid portions to the production process: The vessel is filled and emptied continuously and the green lamp is turned on. When the system is switched off, an ongoing dispensation of a liquid portion must be completed. The red lamp indicates the shutdown until the vessel is emptied.

CIP Specification
The following system description has been generated with CIP Tool®.

COMMUNICATION NET

The system consists of the VesselControl cluster only. The communication net contains correspondingly source and sink channels only. They model the interface to the real external processes.

INTERACTION NET

The straight connectors define the possible pulse transmission paths. The diamond connector enables the vessel process to inspect the RadioButtons process by means of inquiry calls.

PROCESS RadioButtons

INQUIRY isOn
int isOn() {return (STATUS.STATE == on);}

The inquiry isOn is a state vector access function of the process RadioButtons. Such functions return in general information depending on the process state and on the local process variables in the case of extended state machines.

MODE normal

PROCESS Vessel

MODE normal

SWITCH
STATE draining MESSAGE Emptied
TRANSITION 3 IF RadioButtons.isOn()
TRANSITION 4 ELSE

For an occurring Emptied message in the state draining two state transitions are possible (switch). The non-determinism is resolved by allocated disjoint conditions. The inquiry call returns true when the RadioButtons process is in the on state.

PROCESS Lamps

MODE normal