Communication amongst field devices, control unit and programming unit in industrial
automation networks is essential for bulk production, but largely consists of wired networks
that can sometimes be bulky and substantially lack mobility as at times there can arise a need
for a field device to be moved either for maintenance purposes or for rearrangement. There
was therefore a need for wireless communication and PROFIBUS networks that can provide
the minimum movement to field devices or the programing computer. Although wireless
communication technology has penetrated the commercial network, it is still inadequately
utilised in industrial settings due to electromagnetic induction and other forms of interferences
due to industrial machinery. This dissertation introduced wireless communication in a
PROFIBUS network where the MPI section was replaced with the wireless link. The PROFIBUS network technology is a hybrid of protocols where the PROFIBUS DP employs
RS485 technology with a transmission rate of 45 kbps and above while the PROFIBUS PA
employs Manchester Encoded Bus Powered (MBP) technology at a fixed rate of 31.25 kbps.
In RS485 technology, data is transmitted as a voltage difference between the two wires while
in MBP data is transmitted as transitions in current signal and data and power are transmitted
on the same conductors. The PROFIBUS data is also transmitted in the form of telegrams
which further puts a strain on any form of intermediate processing and hence the need for high
speed processing. In this research task the PROFIBUS PA level transmitter measures the
pressure of the fluid in the Blend Chest and sends it to the PLC. The level transmitter was
installed and wired to the PROFIBUS DP/PA coupler. The PROFIBUS network, consisting of
the PLC, variable speed drives, variable speed pumps, delivery pump and level transmitter, was
configured and commissioned for controlling and monitoring from the programing computer.
The program for the PLC was written using Siemens Step-7, compiled and downloaded to the
PLC. The control and monitoring was done using the variable table. The wireless
communication channel was then simulated using Matlab and Simulink. The wireless devices
were then integrated into the PROFIBUS network and the MPI cable linking the programing
computer and the PLC was then replaced by the wireless channel and the network was
controlled and monitored from the programing computer over the wireless channel. On
successful completion of this research task the research plant at MUT was controlled and
monitored from the programing computer over the wireless channel and the researchers and
demonstrators can now access the PLC and the PROFIBUS network using the wireless
communication. / Electrical Engineering / M. Tech. (Electrical Engineering)
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:unisa/oai:uir.unisa.ac.za:10500/22179 |
| Date | 06 1900 |
| Creators | Ndlovu, Wilson Mabalana |
| Contributors | Ohanga, M. O., Naidoo, P. |
| Source Sets | South African National ETD Portal |
| Detected Language | English |
| Type | Dissertation |
| Format | 1 online resource (xi, 76 leaves) : color illustrations |
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