Introduction
The Yokogawa NFAI835 Analog Input/Output Module is a hybrid industrial I/O unit designed for distributed control systems (DCS) such as Yokogawa’s NFA series platforms. It integrates both analog signal acquisition and analog signal output within a single compact module, enabling flexible process monitoring and control in complex automation environments.
Engineered for high stability and precision, the NFAI835 is widely used in process industries where both measurement and control functions must operate seamlessly. Its isolated channel design and fast response capability make it suitable for continuous industrial operations requiring dependable signal integrity.
Technical Specifications
| Parameter | Specification |
|---|
| Model | NFAI835 |
| Manufacturer | Yokogawa |
| Type | Analog Input / Output Module |
| I/O Configuration | 4 AI / 4 AO (isolated channels) |
| 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 Response Time | 100 ms |
| Output Response Time | 100 ms |
| Input Current | Up to 25 mA allowable |
| Load Resistance (Output) | 0–750 Ω |
| Isolation | 500 V AC (channel/system), 500 V AC (channel/channel) |
| Transmitter Supply | 20.2–29.3 V DC |
| Input Resistance | 250 Ω (powered), ≥500 kΩ (unpowered) |
| Temperature Drift | ±0.01% / °C max |
| Operating Temperature | 0°C to +55°C |
| Storage Temperature | -20°C to +70°C |
| Humidity | 5–95% RH non-condensing |
| Dimensions | 150 × 90 × 50 mm |
| Weight | ~0.6 kg |
| Mounting | NFA series rack system |
Applications
The NFAI835 is designed for integrated analog control and monitoring tasks in industrial automation systems.
Typical applications include:
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Oil & gas production monitoring and control
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Petrochemical and refinery process systems
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Power generation and energy distribution systems
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Water and wastewater treatment plants
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Manufacturing process automation
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SCADA and DCS control environments
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Closed-loop industrial control systems
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Instrumentation signal conversion and regulation
Its dual input/output structure makes it especially useful in feedback control loops.
Advantages
The Yokogawa NFAI835 offers strong functional and operational benefits:
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Combined analog input and output in one module 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 real-time process control
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Isolated channel architecture improves system stability and safety
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Flexible 4–20 mA signal handling for industrial compatibility
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Stable long-term operation in harsh environments
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Low temperature drift for consistent accuracy
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Seamless integration with Yokogawa DCS platforms
Technical FAQs
1. What is the main function of the NFAI835 module?
It provides both analog input and analog output functions for industrial control systems.
2. How many channels does it support?
It supports 4 analog inputs and 4 analog outputs.
3. What type of signals does it use?
Standard 4–20 mA analog current signals.
4. Is the module isolated?
Yes, it provides isolation between channels and system backplane.
5. What is the accuracy level?
±0.1% for input and ±0.3% for output.
6. What is the response time?
About 100 ms for both input and output.
7. What is the data refresh cycle?
Approximately 10 ms.
8. What is the operating temperature range?
0°C to +55°C.
9. What is the weight of the module?
Approximately 0.6 kg.
10. What systems is it compatible with?
Yokogawa NFA series distributed control systems.
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