Requirements and current state
Inventory PLCs, source programs, I/O, drawings and licences. Record existing behaviour before claiming equivalence.
Technical design and development
Assess hardware and protocol compatibility. Prepare conversion, interfaces and data migration in a test environment. Agree a downtime window with operations.
Testing and implementation
Verify backups, versions and rollback before migration. Link functions and fault scenarios to acceptance checks. Prepare as-built documentation and maintenance access within scope.