Introduction
The Yokogawa NFAI841-S50 Analog I/O Module is a compact hybrid input/output unit designed for STARDOM FCN/FCJ distributed control systems (DCS). It combines analog signal acquisition and analog signal output functions in a single module, allowing efficient process control, reduced wiring complexity, and flexible system configuration.
This model is widely used in industrial automation environments where both monitoring and control are required in a single hardware slot. Its 8-channel input and 8-channel output architecture makes it suitable for medium-density control applications in process industries.
Technical Specifications
| Parameter | Specification |
|---|
| Model | NFAI841-S50 |
| Manufacturer | Yokogawa |
| Type | Analog Input / Output Module |
| I/O Channels | 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% (input), ±0.3% (output) |
| Data Refresh Cycle | 10 ms |
| Input Step Response | ~100 ms |
| Output Step Response | ~40–100 ms (depending on configuration) |
| Input Resistance | 250 Ω (powered) |
| Load Resistance (Output) | 0–750 Ω |
| Isolation | Non-isolated design (common reference) |
| Transmitter Supply | 22.8–26.4 V DC |
| Power Consumption | ~310 mA (5 V), ~500 mA (24 V) |
| Operating Temperature | -20°C to +70°C |
| Weight | ~0.2–0.25 kg |
| Mounting Type | FCN / FCJ rack system |
Applications
The NFAI841-S50 is designed for integrated process control where both analog measurement and actuation are required.
Typical applications include:
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Oil & gas production and pipeline automation
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Petrochemical and refinery process control systems
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Power generation and turbine control loops
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Water and wastewater treatment systems
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SCADA and DCS distributed automation systems
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Industrial valve and actuator control
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Compressor and pump regulation systems
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Manufacturing process monitoring and feedback control
Its dual I/O capability helps reduce module count and simplify system architecture.
Advantages
The Yokogawa NFAI841-S50 delivers strong industrial benefits:
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8 AI + 8 AO hybrid design reduces system footprint
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High-resolution 16-bit conversion ensures precise signal handling
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Fast 10 ms refresh cycle supports responsive control
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Compact modular architecture simplifies panel design
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Stable 4–20 mA compatibility ensures universal industrial use
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Low hardware complexity improves maintenance efficiency
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Seamless integration with Yokogawa FCN/FCJ systems
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Reliable operation in continuous process environments
Technical FAQs
1. What is the main function of the NFAI841-S50?
It provides both analog input and output processing in a single module.
2. How many channels does it support?
It supports 8 analog inputs and 8 analog outputs.
3. What signal type does it use?
Standard 4–20 mA current loop signals.
4. Is the module isolated?
No, it uses a non-isolated common reference design.
5. What is the accuracy level?
±0.1% for input and ±0.3% for output.
6. What is the refresh cycle?
Approximately 10 ms.
7. What is the response time?
Around 40–100 ms depending on signal direction.
8. What is the load resistance for output?
0–750 Ω typical industrial loop range.
9. What is the weight of the module?
Approximately 0.2–0.25 kg.
10. What system is it compatible with?
Yokogawa STARDOM FCN/FCJ distributed control systems.
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