DMC found corrupted EPROM cards to be the source of the PLC malfunction. DMC connected to a functioning PLC using Simatic STEP5 running on a Windows 98 computer. They uploaded the functioning program from the PLC. DMC completely erased the broken PLCs by removing the EPROM card and battery, and then downloaded a working program to the device. Replacing the battery ensures that the program will be retained on the CPU as long as the battery is alive. This is a temporary fix that allows the client to continue operation while phasing out the S5 PLCs in favor of new S7 hardware. DMC is in the process of converting the code. Siemens has an S5 Converter Tool in the SIMATIC manager package. The tool takes in an S5 program and attempts to output equivalent S7 programming objects. DMC found the tool to be helpful, but not 100% effective. Modifications will likely need to be made to the output of the converter tool in order to ensure proper operation.

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