1. Introduction
Modernizing process instrumentation is critical to maintaining competitiveness in the DACH manufacturing industry. Analogue signals, which have been the standard for decades, are increasingly reaching their limits in terms of diagnostic capability and accuracy. Plant operators are under pressure to meet the requirements of the EU Ecodesign Directive 2009/125/EC and DIN EN 16247-1 on energy efficiency. In addition, the increasing obsolescence of components leads to an increased risk of unplanned downtime. The switch from analog measurement technology to digital protocols such as IO-Link, Profinet or EtherNet/IP enables precise monitoring and optimization of process parameters.
2. Assessment of legacy systems
Before modernization, a systematic inventory of the existing sensors and actuators is required. The following table defines the evaluation criteria.
| criterion | Description | Target value for retrofit |
|---|---|---|
| Accuracy | Deviation from the measured value | < 0.5% of measuring range |
| Signal type | 4-20mA, 0-10V | Digital fieldbus interface |
| Diagnostic ability | Not available | Complete device diagnostics |
| Response time | Mechanically caused | < 10ms |
3. Modern alternatives
Replacing analog components with digital counterparts enables improved process control. In safety-critical areas, such as end position monitoring of hydraulic systems, the use of tested components is necessary. The Telemecanique XCK M 115 - 240V 3A limit switch is a proven, reliable option for reliably reporting the status of mechanical system components to a digital control level.
| Parameters | Analog measurement technology | Digital measurement technology (with IO-Link) |
|---|---|---|
| Data transfer | Analogue (4-20mA) | Digital (bi-directional) |
| Accuracy | ±1.0% | ±0.2% |
| Cost/sensor | Low | Moderate |
| MTBF (hours) | 50,000 | 150,000 |
4. ROI calculation
The profitability of a modernization is based on reducing downtimes and optimizing energy consumption. For a hypothetical system type with a downtime of 4 hours per month and a cost of EUR 5,000/hour:
- Downtime costs: EUR 240,000/year.
- Through digital diagnosis and more precise control, these costs are reduced by 60% to EUR 96,000/year (savings: EUR 144,000).
- Energy savings through demand-controlled pumps/fans: 15,000 kWh/year at 0.25 EUR/kWh = 3,750 EUR/year.
- Total savings in the first year: EUR 147,750. This justifies the investment in new sensors and engineering services within a few months.
5. Implementation Roadmap
- Planning (week 1-2): Analysis of the process requirements and determination of the measuring points according to DIN EN 61131.
- Procurement (week 3-4): Order the components via the UNITEC-D E-Catalog.
- Phased Installation (Weeks 5-8): Replacement during scheduled maintenance windows to avoid interrupting production.
- Commissioning (Week 9): Configuration of the digital interfaces and PLC adjustment.
6. Technical challenges
The most common problems with digitalization are EMC interference with old cable laying and the need to reprogram the PLC. To solve these problems, shielded cables must be used and compliance with VDE 0100-520 must be ensured. The integration of components like the Telemecanique XCK M 115 requires careful mechanical alignment to avoid incorrect switching.
7. Case Study: Hydraulic Press
In a hydraulic press, the analog pressure monitoring was replaced by digital sensors and the end position monitoring was switched to Telemecanique XCK M 115. Result: The error detection time fell from 45 minutes to less than 5 minutes. The MTBF value improved by a factor of 3 because the digital diagnostics report malfunctions before a standstill.
8. Commissioning & Validation
Every exchange must be carried out according to a standardized procedure. This includes checking the signal integrity according to VDE standards, creating protocols for functionality (FAT/SAT) and documenting the measured values in the PLC software.
9. Summary
Modernization is not an optional step, but a necessity for operating efficient industrial facilities. Through the combination of high-quality sensors and robust end position monitoring, obtained from the UNITEC-D E-Catalog, you can significantly optimize your process reliability.
10. References
- EU Ecodesign Directive 2009/125/EC
- DIN EN 16247-1: Energy audits
- DIN EN 61131: Programmable logic controllers
- VDE 0100: Setting up low-voltage systems
