AAI835-H50/K4A00 | Yokogawa | 4–20 mA Analog I/O Module

Product Description

The AAI835-H50/K4A00 is a high-precision analog input/output module developed by Yokogawa for use in distributed control systems requiring stable and isolated current signal processing. This module integrates four analog input channels and four analog output channels within a compact form factor, supporting 4–20 mA signals commonly used in field instrumentation.

Designed for long-term operation in control cabinets, the module ensures accurate signal acquisition and output control while maintaining electrical isolation between channels and the system backplane. Digital communication via HART enables enhanced diagnostics and device parameter access without additional wiring.

Key Functional Characteristics

The AAI835-H50/K4A00 combines bidirectional analog signal handling in a single module, minimizing slot usage and simplifying I/O architecture. Each channel is electrically isolated, reducing noise coupling and improving signal integrity in complex plant environments.

The module supports direct connection through a KS cable interface adapter, allowing clean and reliable integration with Yokogawa control systems while maintaining serviceability.

Technical Specifications

Model

• AAI835-H50/K4A00

I/O Configuration

• 4 analog input channels
• 4 analog output channels
• Channel-to-channel isolation

Signal Type

• Input: 4–20 mA
• Output: 4–20 mA

Input Electrical Characteristics

• Allowable input current: up to 25 mA
• Input resistance (power ON): approx. 290 Ω at 20 mA to 450 Ω at 4 mA
• Input resistance (power OFF): ≥ 500 kΩ

Output Performance

• Output accuracy: ±48 µA

Input Accuracy

• Input accuracy: ±16 µA

Isolation Ratings

• Between I/O and system: 500 V AC for 1 minute
• Between channels: 500 V AC for 1 minute

Communication

• HART digital communication supported

Mechanical Properties

• Dimensions: 107.5 × 32.8 × 130 mm
• Weight: 0.2 kg

Installation Interface

• KS cable interface adapter included (ATK4A-00)

Explosion Protection

• Not provided (standard industrial environment)

Applications

The AAI835-H50/K4A00 is typically deployed in:

• Yokogawa CENTUM DCS systems
• Process control cabinets handling transmitters and control valves
• Analog signal concentration for flow, pressure, temperature, and level loops
• Plants requiring HART-based diagnostics without additional gateways

Model Variant Clarification

Compared to basic AAI835 variants, the H50 suffix indicates HART communication capability, while the K4A00 option specifies compatibility with KS cable interface adapters. This configuration is optimized for modern DCS installations requiring digital device access alongside analog control.

FAQ

Q: Does this module support voltage signals? A: No. The AAI835-H50/K4A00 is designed exclusively for 4–20 mA current input and output signals.

Q: Are the input and output channels isolated from each other? A: Yes. Each channel is electrically isolated, improving safety and reducing signal interference.

Q: Can HART communication operate simultaneously with analog signals? A: Yes. HART digital communication is superimposed on the 4–20 mA signal without affecting normal control operation.

Q: Is this module suitable for hazardous areas? A: No. This version does not include intrinsic safety or explosion protection.