DCS Migration Guide
Strategies for migrating legacy control systems to modern ABB Freelance and System 800xA platforms.
Quick Overview
DCS migration is the process of replacing an aging or obsolete control system with a modern platform. ABB offers migration paths to Freelance (small-medium facilities) or System 800xA (enterprise facilities) from most legacy DCS vendors. Key decisions include migration approach (rip-and-replace, hot cutover, or phased), scope, timing, and whether to reuse existing field wiring.
Why Migrate Your Legacy DCS?
Control systems have finite lifecycles. As systems age, organizations face mounting challenges that eventually make migration necessary:
Obsolete Parts
Spare parts become unavailable or prohibitively expensive as vendors discontinue production.
Cybersecurity Risks
Legacy systems lack modern security features and no longer receive patches or updates.
Vendor Support Ends
Technical support, documentation, and engineering expertise become unavailable.
Limited Integration
Legacy systems cannot integrate with modern analytics, cloud platforms, or IT systems.
Migration Approaches
1. Rip-and-Replace
Complete removal of the legacy system and installation of the new system during a planned shutdown.
Advantages
- Clean installation, no legacy remnants
- Lower total project cost
- Simpler project management
Disadvantages
- Extended downtime required
- Higher startup risk
- Requires shutdown window
Best for: Facilities with planned turnarounds, smaller systems, or processes that can tolerate extended downtime.
2. Hot Cutover
New system installed in parallel with the legacy system, then switched over with minimal production interruption.
Advantages
- Minimal production loss
- Lower startup risk—can test before cutover
- Rollback possible if issues arise
Disadvantages
- Higher project cost (parallel systems)
- More complex project execution
- Requires space for temporary equipment
Best for: Continuous processes where downtime is extremely costly, critical facilities, or risk-averse organizations.
3. Phased Migration
Gradual replacement of the legacy system area by area or unit by unit over an extended period.
Advantages
- Spread capital investment over time
- Learn and improve with each phase
- Align with maintenance windows
Disadvantages
- Longer total project duration
- Must maintain two systems simultaneously
- Integration between old and new required
Best for: Large facilities, limited capital budgets, or when migration can align with planned expansions or unit turnarounds.
Planning Considerations
1. Documentation Assessment
Evaluate existing documentation: P&IDs, loop sheets, control narratives, graphics. Poor documentation increases engineering effort and risk. Consider as-built documentation projects before migration.
2. I/O and Field Device Inventory
Catalog all I/O points, field devices, and communication protocols. Identify devices that need replacement versus those that can interface with the new system. Plan for instrument calibration and testing.
3. Control Strategy Review
Migration is an opportunity to optimize control strategies. Review PID tuning, batch sequences, and interlocks. Consider which logic to replicate exactly versus which to improve.
4. Operator Training
Plan comprehensive operator training on the new system. Consider simulation-based training before cutover. Involve operators early to capture process knowledge and build buy-in.
5. Spare Parts Strategy
Establish spare parts inventory for the new system. Consider ABB's lifecycle services and spare parts programs. Plan for disposal of legacy spare parts.
ABB Migration Solutions
ABB provides migration tools and methodologies for transitioning from various legacy platforms:
To ABB Freelance
Ideal for small to mid-size facilities seeking an efficient, cost-effective DCS with modern capabilities.
- DigiVis engineering environment
- AC700F/AC800F/AC900F controllers
- Integrated HMI and historian
To ABB System 800xA
For enterprise facilities requiring integrated process, electrical, and safety control.
- AC800M high-performance controllers
- Electrical integration (IEC 61850)
- Integrated safety systems
Common Legacy Systems
ABB has migration experience from most major legacy DCS platforms:
Frequently Asked Questions
Why should I migrate my legacy DCS?
Legacy DCS systems face increasing risks: obsolete spare parts, lack of vendor support, cybersecurity vulnerabilities, inability to integrate with modern systems, and difficulty finding engineers with legacy expertise. Migration reduces these risks while enabling modern capabilities.
What migration approaches are available?
Three main approaches: (1) Rip-and-replace: complete system replacement during a shutdown; (2) Hot cutover: parallel installation with live switchover minimizing downtime; (3) Phased migration: gradual replacement area by area over time. The best approach depends on process criticality, budget, and operational constraints.
How long does a DCS migration take?
Migration timeline varies significantly based on system size, complexity, and approach. A small system rip-and-replace might complete in weeks; a large phased migration can span years. Planning and engineering typically take 3-12 months before any field work begins.
Can I keep my existing I/O wiring during migration?
Often yes. ABB offers I/O marshalling solutions that can connect to existing field wiring, avoiding expensive rewiring. This is especially valuable for hot cutover migrations where the new system parallels the old before switchover.
What legacy systems can migrate to ABB Freelance or 800xA?
ABB has migration paths from most major legacy platforms including: older ABB systems (Advant, MOD 300, Symphony), Honeywell TDC/Experion, Emerson DeltaV/Ovation, Yokogawa CENTUM, Foxboro I/A, Bailey INFI 90, and many others. Contact us for your specific legacy system.
Related Guides
Planning a DCS Migration?
With 35+ years of ABB automation experience, Gross Automation can help you plan and execute your migration to modern ABB Freelance or System 800xA—and provide competitive pricing on all components.
ABB Freelance DCS design, panels and long-term support: meet our Freelance engineers.