An online and offline programmable multi-loop controller for distributed systems

Abstract

We present a PEARL (Process Experimental Automation Real-time Language)-based multi-loop control-unit for distributed systems, which allows consistent configuration of closed-loop and sequence-control tasks in a function block oriented approach. The tasks can be configurated and parametrised either with a sequence of commands in a menu driven way or, graphically, in a WINDOWS oriented way. The extensive function block library contains many different function blocks for conventional and modern control-algorithms. The function blocks that are needed to configurate tasks for sequence-control and those which are needed for identification, filtering and process I/O are available as well. The performance of a control-unit is also assessed by comparing the control-unit communicates with the other approaches. We show that it is possible to reduce significantly the needed calculating time for sequence-control tasks if a real-time management is used, which allows a periodic scheduling as well as an aperiodic scheduling. We also demonstrate that, if a complex sequence-control algorithm is divided up into small synchronised parts, it is possible to reduce the calculating time even more.<>