Four Spare Parts Every Siemens S7-400 Site Should Keep on the Shelf

A short spares list for plants running SIMATIC S7-400 controllers.

The S7-400 is built for demanding, high-availability applications, so a failure usually matters. A short list of spares can turn a long outage into a quick swap.

  1. CPU: the one module you cannot do without. Match the exact order number and firmware.
  2. Power supply: the most common cause of rack failures after years of operation.
  3. Communication processor: needed for Ethernet or PROFIBUS connections.
  4. One of each I/O module type used in your rack.

Storage tips

  • Keep spares in antistatic bags in a dry cabinet.
  • Label each module with its order number and firmware.
  • Power them up occasionally to check that they still work.

See our S7-400 modules or request a quote for a spares bundle.

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