Hey there! I totally get your concern about the Siemens S7-200 SMART discontinuation - it's a real headache when you've got machines that need to keep running for another decade or more. Here's what I'd recommend for building a resilient spare parts strategy:

First, do a complete audit of your current S7-200 SMART installations. Create a detailed spreadsheet with part numbers, serial numbers, installation dates, and which machines they're in. This helps you identify your "single points of failure" - the critical components that would cause the most downtime if they failed.

Next, prioritize immediate procurement of buffer stock for the most critical components like CPUs, power supplies, and key I/O modules. Siemens typically offers spare parts for a while after discontinuation, but availability will shrink over time. Consider buying from authorized distributors who might have remaining stock.

For the long term, you should explore replacement alternatives. Siemens recommends migrating to S7-1200 or S7-1500 series, and they provide migration tools in TIA Portal. There are also third-party compatible options like UniMAT that offer functional equivalence with S7-200 SMART.

Create a phased migration plan - start with non-critical machines to test the waters, then gradually upgrade your most critical systems. This approach spreads out costs and minimizes risk.

Finally, consider partnering with specialized suppliers who focus on obsolete automation parts - they often have access to remaining stock or can source compatible alternatives when you're in a pinch.

The key is balancing immediate spare parts procurement with a long-term migration strategy. It's a bit of a juggling act, but with proper planning, you can keep those machines running smoothly for the next 10+ years!