During virtual commissioning, the generated process simulation is connected to the real control. As a general rule, there are three different levels:
• PLC / Robot control level
• Material flow level
• Main computer / Production control level
The simulation model always covers the level which is not part of the test setup. If e.g. the PLC logic is meant to be tested, the model only covers the sensor / actor level. When testing the material flow level, the model also covers the PLC logic. Mixed forms in which the PLC of several plant sectors are available can also be realized, missing parts are taken over by the model.
PLC / Robot control level
Here, the virtual system is connected to and controled by the real PLC. The actor signals (control signals for motors, valve open/close, proportional valve control, …) and PLC control words are interpreted and control the model. Latter sends the sensor and feedback signals (photo sensors, temperature sensors, barcodes, pulse encoders and encoder values, feedback signals, switches, …) back to the PLC. For the PLC software, there is no difference between model and real plant, the model acts 100% like the real machine. Thus, the PLC logic can be tested before the plant is actually in operation.
- Phase 1: Preparation
For the graphic modelling of new or non-available plant components within the simulation platform, CAD data from an early construction phase are used. If not available or not required, abstract geometric modules are applied. According to the project requirements, PLC (real or virtual), robot control, control panel and further components are connected to the virtual system. Some first software modules of the respective control are realized, failure contures and functionality are tested.
- Phase 2: Implementation
Here, mounting resp. implementation is effected. The so far virtually simulated components (robot, conveyance, …) are replaced by real components. Furthermore, wiring of the plant components and first function tests are realized.
- Phase 3: Evaluation
Real commissioning and evaluation. PLC and robot programming are completed, the wiring of so far not connected components with the plant control is effected. The control software is technically highly matured, only very little changes are required.
Material flow level
During the virtual commissioning on material flow level, material flow computer and simulation model communicate on telegram level. The computer sends orders to the system and asks for status messages. As such, it e.g. effects various transport orders for the warehouse management system, surveys conveyance paths and hands the data on to the PLC model. Here, the simulation is able to picture, test and optimize the control of each automated control, conveyor and sorting element.
Main computer / Production control level
Test of the scheduling system (communication between simulation model and main computer on telegram level.
• Picture of the PLC logic within the simulation model
• Definition of a communication interface on the basis of telegrams exchanged between simulator and main computer