Introduction to simulation

In real operation of a process automation plant, changes in values are detected by peripheral devices such as sensors or probes. Components such as Fieldbus systems or controllers communicate and process the data and return it to the master computer through busses and drivers. A simple simulation program has been implemented in the DemoApplication in such a way that you encounter reasonably realistic conditions even though you are not connected to an actual process.

All simulation processes (except in the "Production" process display) are handled by a central Control script. This script (<proj_path>/scripts/da_simulate.ctl) runs in a Control Manager with the call parameter vss_scripts.lst, together with two other runtime scripts. The script consists of four logically different sections:

  • State signal simulation

  • Value simulation

  • Process simulation

  • Controller simulation

Simulation can be enabled or disabled on a global basis for all three areas by selecting first the Start cascade option "Simulation", then the menu option "Start" or "Stop".

Simulation Description
State signal simulation Response to a command previously sent to a peripheral device
Value simulation Values are generated by a Control script and written to data points.
Process simulation Changing process values are displayed depending on the operating mode of objects.
Controller simulation Controller simulation shows a chemical reaction tank with a heat exchanger to control reaction and thermal conditions. Different controller settings have been created and saved for the PID controller. The controller settings are LICA configurations. These show the functionality of the controlled system and the influence of the controller parameters on the control system's behavior.
Simulation directly in a process display Control scripts for simulation purposes run directly in graphic objects of the plant display.

If the simulation has been started from the options in the Start cascade, only those simulation areas that are enabled in the Properties Panel under the individual simulation modes are activated.