Design And Development Of PLC Loop Control Software Functional Test Platform For Industrial Process

Before process control system, especially PLC control software, is put into field operation, it needs a series of venturesome, time and energy consuming testing processes. Therefore, testing PLC control software in laboratory environment in advance to find and correct errors in it is very significant to shorten testing times, to save manual labor, to reduce testing venture and to cut the cost of testing.Although in process control, the control loop represented by single PID loop, cascade loop and ratio loop, whose controller’s core are the controller parameters, but the right functions of the human-machine interaction and manual and automatic switching are also the premise guarantee of making the loop controllers working normally. This paper supported by National Science and Technology Supporting Program "Advanced Control Technology of Whole production Line of Mineral Processing" (2012BAF19G01), studied the testing method of function of PLC loop control software in industrial process, and conduct the design and development of testing platform. The concrete work includes:1. Based on the analysis of all the functions that involved in PLC loop control software, and combined with common loop control method in industrial process, we made a concrete discussion on programming errors and testing requirement in the functional design of PLC loop control software.2. On this basis, taking PLC loop control software of the control system and the labels of system I/O access as the foundation, a testing method based on human-machine interaction and black box testing is proposed and the overall architecture of the testing platform for PLC loop control software functional testing consisting of test case library, test process control module, judgment and record modules, OPC communication modules and human machine interaction is designed, which can realize semi-automatic test for function setting of PLC loop control software in industrial process and automatically produce test reports.3. Industrial process loop control function testing platform in accordance with Rockwell PLC system is developed based on PLC software development environment of Rockwell’s RSview32, OPC communication technology and VBA scripting methods.4. Taking the automation engineering PLC loop control software of a certain iron factory as case, testing methods and testing platform mentioned in this paper are checked. The results show that testers can quickly find and locate errors and defects in PLC software loop control function with the help of this platform. This can make a contribution to shorten testing time, to save the cost of manual labor, to reduce testing venture, and to lower testing investment.