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African Petrochemicals is South Africa’s leading quarterly print and digital trade magazine for the past 15 years. Featuring all the latest petrochemical industry news, special reports, technological advances and much more.


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Ai2SA successfully replaces HMI on archaic Mitsubishi A series PLC

Architects Integrating Industry (Ai2SA), specializing in “optimally managing and scoping industrial systems projects” was recently contracted to replace a faulty Human Machine Interface (HMI) on an archaic Mitsubishi “A” Series PLC. Initially we looked at reducing client’s cost by repairing the faulty HMI dating back to 2004 however this proved in practical as a result of spares being unavailable and also costing too much to import these.

A decision was then made by client to decommission the line however we managed to convince client not to as it would mean that client could not be able to sell on faulty line to other smaller operations looking at starting similar business. Ai2SA then proceeded with some research to identify an HMI which would be able to communicate to the PLC CPU which was dating back to the 1980s. An HMI was identified, and re-engineering started using a backup from another migrated line which required significant changes as new unit was only available with touch panel functionality not external key pad, etc.

During initial commissioning we found that the OEM documentation was incorrect in that unit did not offer RS422 communications as used by the PLC and so we had to procure at our cost an additional RS232/RS422 convertor. The project was completed and signed off by the customer who via a migration of the HMI was able to increase life of the production line increasing their return on investment and profitability. A screen shot of converted HMI is depicted below reflecting the Ai2SA color scheme.


It is important to note when attempting to connect present day technology with that dating back from the 80s that reading manuals may not always provide all answers and that some risks are to be expected and allowed for. It is also important for clients to know that it is possible to migrate technology increasing serviceable life of money producing equipment. Feel free to contact us for more information.



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