A data bridge interface between the legacy GE control system and the new Siemens upgrade was designed and commissioned for Siemens at AHMSA's hot strip mill in Monclova Mexico. The data bridge allowed simultaneous operation of and data exchange between both old and new control systems. This allowed Siemens to incrementally commission the new control system one sub-system at a time.
A C-Bus interface was added to the existing CL3 coiler controller as shown in the diagram below. An additional software task was added to the CL3 controller that transferred data between CSF global and the newly added C-Bus. The transfer program was table driven making it relatively easy to maintain and modify.
A GE PAC-7 module capable of both C-Bus and Profibus connectivity provided hardware compatibility between the two systems. Although this required additional and redundant programming, it was necessary. Ironically, the newer PAC-7 lacked the efficient table transfer capability of the older DMC controller, making it somewhat more onerous to program.
The #3 coiler sub-system was upgraded with new drive and controller in conjunction with commissioning of the data bridge. The remaining sub-systems were incrementally upgraded and commissioned over a period of time, all the while maintaining normal production levels.