A system integrator in Africa decided to try a new approach during a system upgrade at a commercial grain mill. The customer needed to upgrade their control system from Modbus serial devices to new PLCs. This kind of upgrade typically requires round-the-clock shifts over several days manning both the old and new systems simultaneously, because they cannot communicate in parallel and lost production must be minimized. In addition to the overtime and sleepless nights during the changeover, when an operator selected an operation from the old system, operators and engineers testing the new system could not see the changes, causing delays and increasing the chance of error.
Faced with these challenges, the system integrator looked into the possibility of running both systems in parallel, and found the Cogent DataHub. With the help of Cogent’s partner, Software Toolbox, he was able to configure a link between the I/O driver on the old system and the OPC server on the new system. Although the old system used DDE, and the new system OPC, the DataHub converted the data protocols; its bidirectional Tunnel/Mirror feature allowing both HMIs―old and new―to view the data from either set of PLCs, old or new. The new SCADA system could run concurrently with the old one, using an identical data set. As a result, the company was able to save 21 million dollars on the switchover.