Yokogawa AAI135-S50 8-Channel Isolated 4–20 mA Input Module
An eight-channel isolated current input module for 4–20 mA field signals in supported CENTUM VP node units.
Product Overview
AAI135-S50 is the Yokogawa AAI135 analog input module with eight isolated 4–20 mA channels. Field and system circuits are isolated, and each input channel is isolated from the others.
The module supports two-wire transmitter input or four-wire current input wiring through the documented terminal arrangement. HART communication is available in the supported system configuration.
A Zener barrier must not be connected to this module. Yokogawa specifies an isolation barrier for an intrinsically safe application, and the approved node unit, terminal hardware and cable must remain part of selection.
Performance
Isolated current acquisition
Converts eight independent 4–20 mA process signals for the CENTUM control environment.
Transmitter supply support
Provides the documented terminal arrangement for compatible two-wire transmitters.
HART availability
Supports HART communication when the installed system and associated hardware meet the Yokogawa requirements.
Redundant architecture
Can be used in the approved dual-redundant module configuration.
Technical Details
| Manufacturer | Yokogawa | Exact model | AAI135-S50 |
|---|---|---|---|
| Product designation | Analog Input Module | Input channels | 8, isolated |
| Input signal | 4 to 20 mA | Allowable input current | 25 mA |
| Accuracy | ±16 µA | Data update period | 10 ms |
| Input resistance, power on | 290 Ω at 20 mA to 450 Ω at 4 mA | Input resistance, power off | 500 kΩ or greater |
| Channel-to-system withstand | 500 V AC for 1 minute | Channel-to-channel withstand | 500 V AC for 1 minute, subject to cable limits |
| Temperature drift | ±16 µA per 10 °C | Maximum current consumption | 360 mA at 5 V DC; 450 mA at 24 V DC |
|
HART communication |
Available | External connections | Pressure clamp terminal, MIL connector cable or KS1 dedicated cable |
About IndustryParts
https://www.industryparts.com/Current loops are reviewed as complete circuits
IndustryParts keeps the module identity, transmitter wiring, barrier choice, terminal hardware and channel map together before supply.
- Exact submitted model retained
- Installed-system evidence reviewed
- Quotation identity kept traceable
System Integration
Map every loop
Record transmitter type, power source, polarity, cable, shielding, range, engineering units and channel assignment.
Choose the safety interface
Use an approved isolation barrier—not a Zener barrier—when the intrinsically safe design requires a barrier.
Commission with known current
Inject or apply approved test values and verify scaling, HART access where used, alarms and channel isolation.
Applications
Process transmitter inputs
Acquiring isolated 4–20 mA signals for pressure, flow, level and temperature loops.
HART-enabled maintenance
Accessing supported HART information through the approved CENTUM architecture.
Redundant input service
Using paired modules where the Yokogawa system design calls for dual redundancy.
FAQ
Can a Zener barrier be used with AAI135-S50?
No. Yokogawa specifies an isolation barrier when the module is used in an intrinsically safe application.
What loop information should accompany a AAI135-S50 enquiry?
Provide transmitter type, two-wire or four-wire arrangement, power source, range, barrier type, terminal hardware and channel map.
Does AAI135-S50 support HART communication?
Yes, within the supported CENTUM configuration and associated node-unit or firmware requirements.
What happens to the loop when AAI135-S50 is unpowered or abnormal?
Yokogawa states that the current input loop is open; shared-receiver designs therefore require special review.
What proves AAI135-S50 is ready after replacement?
Known-current checks, correct engineering scaling, stable channel status, verified isolation and any required HART test complete the record.
Recommended Models
Send the complete AAI135-S50 identity
Include requested quantity, destination and the installed-system evidence needed for compatibility review.
