Profibus network in the instrumentation and control laboratory

The Instrumentation and Process Control Laboratory is facility that provides Engineering students a way of performing control experiments by using a combination of instrumentation hardware and LabVIEW programs. The Laboratory is based upon three components: - The Experimental Stations - The Master I/O Program - The Basic Experimental Template The Experimental stations are panels where hardware components like valves and measuring devices are connected to. The Master I/O program is a LabVIEW program which acts as an interface between the Experimental Stations and the Basic Experimental Template. The Basic Experimental Template is a LabVIEW program which stundents can modify to suit their designs for process control experiments. The main aim of this project is to integrate the PROFIBUS PA instruments into the Master Input/Output (I/O) program and to produce a guide to assist students in using these instruments. This project involves communication between instruments from different vendors, hence the use of open and vendor independent protocols. Once completed, the project will avail more instruments to be used for process control experiments. The project also avails another infrastructure for students studying Industrial Computer Engineering to use the physical PROFIBUS network when learning about industrial communication systems. Even though PROFIBUS PA instruments are more accurate and fast, their response in controlled by the scan cycle of the Master I/O Program. The communication protocols used in this project are PROFIBUS PA, OLE for Process Control (OPC) and Ethernet. The PROFIBUS protocol is vendor independent and based on the master and slave architecture. The SIEMENS CPU314C-2DP is used as the master, while the slaves are the Siemens DP/PA coupler, Levelflex M FMP40 and Deltbar S PMD70. Communication between the slaves and the master was via the PROFIBUS PA protocol. The configuration and programming of the SIEMENS CPU314C-2DP and PROFIBUS PA devices was done using TIA Portal V13 software. Communication between an OPC server and CPU314C-2DP was via a serial communication port using an MPI cable. The OPC server was configured to read the required data from the iv CPU314C-2DP. The Master I/O program was updated to read data from the OPC server using shared variables and calculate the measured parameters. The OPC server and Master I/O program were running on the same computer. Finally, the experimental template was updated to read data from the Master I/O program using Ethernet as the medium of communication. The communication and programs were tested at the end of each stage to ensure functionality of each segment. In overall, the objectives of this project were achieved as the PROFIBUS PA instruments can now be used in the laboratory, and the guide on how to use them was developed