Introduction
The Yokogawa NFAI841-S50 S2 Analog I/O Module is a compact hybrid input/output module designed for STARDOM FCN/FCJ distributed control systems (DCS). It provides both analog signal acquisition and analog signal output in a single hardware unit, helping reduce system footprint while maintaining reliable process control performance.
This module is widely used in industrial automation environments where stable 4–20 mA signal handling, fast response, and long-term operational reliability are required. The S2 designation typically indicates a revised or enhanced hardware/production variant within the same product family, often associated with improved compatibility or manufacturing optimization.
Technical Specifications
| Parameter | Specification |
|---|
| Model | NFAI841-S50 S2 |
| Manufacturer | Yokogawa |
| Type | Analog Input / Output Module |
| I/O Configuration | 8 AI / 8 AO (non-isolated) |
| Input Signal | 4–20 mA DC |
| Output Signal | 4–20 mA DC |
| Resolution | 16-bit A/D & D/A conversion |
| Accuracy | ±0.1% full scale (input) / ±0.3% (output) |
| Data Refresh Cycle | ~10 ms |
| Input Resistance | 250 Ω (powered) |
| Load Resistance | 0–750 Ω (output loop) |
| Overcurrent Protection | Supported |
| Power Consumption | ~310 mA (5 V), ~500 mA (24 V) |
| Operating Temperature | -20°C to +70°C |
| Weight | ~0.2 kg |
| Dimensions | ~130 × 27.5 × 90 mm |
| Mounting Type | FCN / FCJ rack system |
Applications
The NFAI841-S50 S2 is designed for integrated process automation where both measurement and control are required in the same loop structure.
Typical applications include:
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Oil & gas production monitoring and control
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Petrochemical and refinery automation systems
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Power generation plant instrumentation
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Water treatment and distribution control
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SCADA and DCS process control networks
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Compressor, pump, and valve control loops
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Manufacturing process optimization systems
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Industrial signal acquisition and feedback control
Its hybrid architecture reduces hardware complexity and improves system integration efficiency.
Advantages
The Yokogawa NFAI841-S50 S2 provides strong operational value in industrial environments:
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8-channel input + 8-channel output hybrid design reduces module count
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High-resolution 16-bit conversion ensures precise analog handling
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Fast 10 ms refresh cycle supports real-time process response
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Industrial 4–20 mA compatibility ensures wide field device support
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Compact rack design reduces cabinet space requirements
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Stable long-term operation for continuous industrial processes
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Simple integration with Yokogawa STARDOM systems
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Reliable performance in electrically noisy environments
Technical FAQs
1. What is the main function of the NFAI841-S50 S2 module?
It provides both analog input and analog output functions for industrial control systems.
2. How many channels does it support?
It supports 8 analog input channels and 8 analog output channels.
3. What signal type does it use?
Standard industrial 4–20 mA DC signals.
4. Is the module isolated?
It is a non-isolated design (common reference architecture).
5. What is the accuracy level?
Approximately ±0.1% for input and ±0.3% for output.
6. What is the refresh cycle speed?
Around 10 ms data refresh cycle.
7. What is the output load range?
0–750 Ω loop resistance.
8. What is the weight of the module?
Approximately 0.2 kg.
9. What does “S2” mean?
It generally indicates a revised production or enhanced version within the same module family.
10. What systems is it compatible with?
Yokogawa STARDOM FCN/FCJ distributed control systems.
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