SMALL STEPS, BIG PAYOFF
The German manufacturer was sold during the install of a $10M production line. Maintenance had to find support for their new equipment. We had only two brief service visits to the plant prior to Roger’s call. We came in to find the most complex Siemens application I have encountered.The S7-417 safety PLC connected to 7 other S7 processors over 8 Profibus networks. The main cabinet is a walk-in box featuring banks of drives, breakers, starters, fault monitors, and controllers. Only the hardware manual set containing several thousand drawings were documented in both German and English. The program code was promised in English but not delivered. Tech support became erratic as performance/ payment negotiations broke down.
TRANSITION TO INDEPENDENCE Our relationship grew stronger as we solved more production issues. The language barrier hindered our tracing efforts. Failures in the safety circuit were compounded by passwords restricting access to the code. Help came from the installation technician who stayed in the US to service equipment built by the new parent company.
Training moved to the top of needs list. Several techs from other Hood plants were brought in to take advantage of the Siemens training. We focused on shortening diagnostic time through the use of software tools. Normally, 95% of the failures are field devices like encoders, valves, and motors. This application has shown 40% of the issues occur between communication components. These faults are typically sporadic and are difficult to locate. A well organized and heavily alarmed process narrows the search.
TELESERVICE SAVES TIME Cost prohibits having every spare part at the plant. We view status over the telephone using modems and optional equipment. Hardware failures can be diagnosed and after physical confirmation ordered for urgent delivery. Cost and stress are reduced by quick diagnostics while potential help becomes global.
TRANSLATING THE PROGRAM Technical German is extremely difficult to decipher. We selected the sections of the program that were related to messaging, start-up inhibit, and PLC data exchange as our starting point. It took a team effort to bridge the gap between alarms and the component that faulted.