S7-400 is the high-availability SIMATIC platform found in large process plants — cement, fertiliser, oil and gas, water — where redundant CPUs and hot-swap I/O matter more than footprint. We supply CPUs, PS power supply modules, UR/ER racks, signal and communication modules, plus SIPLUS variants, as spares for installed systems.
Redundant (H) systems require matched CPU pairs and specific sync modules — confirm the full configuration, not just the failed part.
Rack, power supply and CPU are separate order codes; a CPU alone does not restore a failed rack.
Record firmware versions — mixing versions in an H-system will prevent synchronisation.
Many S7-400 parts are now stock-driven; give us as much notice as possible for planned shutdown spares.
Frequently asked questions
Is S7-400 still available?
It is late in its lifecycle and supply is increasingly stock-driven rather than production-driven.
What is the migration path from S7-400?
Siemens positions the S7-1500 and, for process plants, PCS 7 / PCS neo as the forward path. That is a project, not a swap — for an immediate breakdown, a like-for-like spare is normally the right call.