The True Cost of PLC Migration: A Realistic Calculation
Realistic cost breakdown for migrating a Siemens S5 PLC to S7-1500. Covers hardware, software licenses, engineering hours, commissioning, and hidden costs with concrete price ranges for small, medium, and large systems.
The True Cost of PLC Migration: A Realistic Calculation
A Siemens S5→S7-1500 migration costs €5,000–€15,000 for a small standalone machine, €20,000–€80,000 for a medium production line, and €100,000+ for large multi-CPU systems. The three main cost drivers are engineering hours (50–70% of total cost), hardware (20–35%), and software licenses (5–15%). This guide breaks down every cost component so you can build a realistic budget.
The Three Cost Blocks
1. Hardware (20–35% of total cost)
S7-1500 CPU: The new CPU is often the largest single hardware cost.
| S7-1500 CPU | Typical Use | Approximate Price |
|---|---|---|
| CPU 1511-1 PN (150 KB) | Small machines, replaces S5-90U/95U/100U | ~€1,000–1,500 |
| CPU 1513-1 PN (300 KB) | Medium machines, replaces S5-115U | ~€2,000–3,000 |
| CPU 1515-2 PN (500 KB) | Large machines, replaces S5-135U | ~€3,500–5,000 |
| CPU 1516-3 PN/DP (1 MB) | Complex systems with PROFIBUS + PROFINET | ~€5,000–7,000 |
| CPU 1517-3 PN (2 MB) | High-performance, replaces S5-155U | ~€8,000–12,000 |
I/O modules: Depends entirely on the I/O count. Digital I/O modules (16/32 channel) cost €100–400 each. Analog modules cost €300–800 each. A typical small machine with 32 DI, 16 DO, 4 AI, 2 AO might need €1,000–2,000 in I/O modules.
I/O adapter modules: If you reuse existing S5 I/O racks instead of replacing all field wiring, Siemens IM adapter modules cost €500–1,500 per rack. This saves significant wiring time but adds hardware cost.
Power supply, rack, memory card, cables: Budget €500–1,500 for these supporting components.
Typical hardware costs by system size:
| System Size | I/O Points | Hardware Cost |
|---|---|---|
| Small (standalone machine) | 30–80 | €2,500–5,000 |
| Medium (production line) | 80–300 | €5,000–15,000 |
| Large (multi-CPU plant) | 300–1,000+ | €15,000–50,000+ |
2. Software Licenses (5–15% of total cost)
TIA Portal STEP 7 Professional: Required for programming S7-1500. A new license costs approximately €3,000–5,000 (one-time purchase, floating or single license). If you already have TIA Portal for other projects, this cost is zero.
TIA Portal options: Safety (F-modules), WinCC (HMI), SCL, GRAPH — each option adds €500–2,000. Not all are needed for every project.
PLCSIM: Simulation tool for testing, typically included in STEP 7 Professional or available for €500–1,000.
If you are migrating multiple machines, the software license is a one-time cost that amortizes across all projects. For a single migration, it can be 10–15% of the total budget. For ten migrations, it becomes negligible per project.
3. Engineering (50–70% of total cost)
Engineering is almost always the largest cost block. It includes analysis, conversion, testing, and commissioning.
Engineering hourly rates (2026, Western Europe/US):
| Role | Hourly Rate |
|---|---|
| Siemens integrator / system house | €100–180/hour |
| Freelance PLC programmer | €80–150/hour |
| In-house automation engineer | €50–80/hour (fully loaded cost) |
Engineering hours by system size:
| System Size | Analysis | Conversion | Testing | Commissioning | Total Hours |
|---|---|---|---|---|---|
| Small | 8–16 h | 16–40 h | 8–16 h | 8–16 h | 40–88 h |
| Medium | 16–40 h | 40–120 h | 16–40 h | 16–40 h | 88–240 h |
| Large | 40–80 h | 120–400 h | 40–80 h | 40–120 h | 240–680 h |
What drives engineering hours up:
- No documentation (add 30–50% for reverse engineering)
- Complex indirect addressing (DO, LIR, TIR — requires deep S5 expertise)
- Many different timer types and data block configurations
- HMI/SCADA migration required alongside PLC
- Safety-related functions (SIL/PL requirements, re-validation needed)
- Multi-CPU systems with inter-PLC communication
Total Cost Summary
| System Size | Hardware | Software | Engineering | Total |
|---|---|---|---|---|
| Small (single machine, 30–80 I/O) | €2,500–5,000 | €0–5,000 | €3,200–13,200 | €5,000–15,000 |
| Medium (production line, 80–300 I/O) | €5,000–15,000 | €0–5,000 | €7,000–36,000 | €20,000–80,000 |
| Large (multi-CPU, 300–1,000+ I/O) | €15,000–50,000 | €3,000–10,000 | €19,000–102,000 | €100,000–250,000+ |
Note: These ranges assume the S5 program source code is available. If only the binary in the PLC exists and no source code backup, add 20–50% for program extraction and reverse engineering.
Hidden Costs Most Budgets Miss
Production Downtime
The cutover from S5 to S7 requires shutting down the machine. Depending on cutover strategy:
- Big bang: 1–3 days of downtime for installation + testing
- Gradual with adapters: Multiple shorter windows (4–8 hours each)
- Hot standby: Minimal downtime but higher hardware cost
Calculate your downtime cost: If your production line generates €10,000/day in revenue and you need 2 days of downtime, that is €20,000 in opportunity cost — often more than the entire hardware cost.
HMI/SCADA Migration
If the machine has an operator panel (OP/TP/MP series) that communicates with the S5, it may also need replacement or reconfiguration. An old OP7 or OP17 connected via MPI to an S5 cannot directly communicate with an S7-1500 via PROFINET. Budget €2,000–10,000 for HMI migration depending on complexity.
Electrical Cabinet Modifications
The S7-1500 has different physical dimensions than S5. The DIN rail mounting is different, cable routing may need adjustment, and PROFINET cabling replaces MPI or PROFIBUS DP connections. Budget €1,000–5,000 for cabinet modifications.
Documentation and Training
After migration, the documentation needs updating: I/O lists, wiring diagrams, operating instructions. If your maintenance team needs TIA Portal training, budget €2,000–5,000 per person for a Siemens training course (typically 5 days).
How to Reduce Migration Costs
1. Use PLCcheck Pro for initial analysis. Automated code analysis identifies all timers, addresses, data blocks, and special functions in minutes instead of hours. This cuts the analysis phase by 50–70%.
2. Reuse I/O wiring with adapter modules. This eliminates the most time-consuming electrical work: disconnecting and reconnecting field wiring. The IM adapter modules cost a fraction of the labor saved.
3. Migrate during planned maintenance windows. Every unplanned hour of downtime costs more than a planned hour. Schedule the cutover during existing shutdown periods.
4. Use in-house engineers if you have them. At €50–80/hour fully loaded vs. €100–180/hour for external integrators, in-house engineering can save 30–50% on the largest cost block. PLCcheck Pro makes this feasible even for teams without deep S5 expertise.
5. Batch multiple migrations. If you have 5 machines with S5, migrate them as a project. The TIA Portal license, training, and learning curve are one-time costs. Each subsequent migration is faster and cheaper.
Get a free migration estimate with PLCcheck Pro →
Frequently Asked Questions
Is it cheaper to keep repairing S5 than to migrate?
In the short term, a €800 refurbished CPU module is cheaper than a €15,000 migration. But refurbished parts have limited warranty, uncertain lifespan, and rising prices. A single unplanned failure that causes €50,000+ in downtime costs more than the migration. The break-even point is typically 2–3 years.
Can I migrate in-house or do I need an external integrator?
If you have a maintenance team with PLC programming experience and TIA Portal knowledge, in-house migration is feasible for small-to-medium systems. PLCcheck Pro can bridge the S5 knowledge gap. For large or safety-critical systems, an external Siemens Solution Partner is recommended.
Do I need to replace the entire electrical cabinet?
Usually not. The S7-1500 can often be mounted in the existing cabinet with modified DIN rails. I/O adapter modules preserve existing field wiring. Full cabinet replacement is only needed if the cabinet itself is in poor condition or undersized.
What is the ROI of PLC migration?
Direct ROI comes from eliminated unplanned downtime, reduced spare parts spending, and lower maintenance effort. Indirect ROI comes from faster troubleshooting (TIA Portal diagnostics vs. STEP 5), future expansion capability, and meeting modern safety/compliance standards. Most companies recover migration costs within 2–4 years through avoided downtime alone.
Maintained by PLCcheck.ai. Last update: March 2026. Not affiliated with Siemens AG. Prices are approximate and based on 2025/2026 market data. Actual costs vary by region, distributor, and project specifics.
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