Yokogawa ALU4*D Analog Input Module

Configured for high-speed signal conditioning and analog data collection in distributed control systems (DCS), the Yokogawa ALU4*D (ALU4*D Analog Input Module) provides direct physical/electrical execution.

Hardware Specifications

Process Control System Specifications

• 4-20 mA HART Loop Protocol Network Arbitration The analog circuitry interfaces with external field transmitters to process incoming process variables like temperature, pressure, and flow. The module handles signal conditioning by filtering and amplifying raw electrical signals before converting them into synchronized digital values for communication bus transmission.
• Channel-to-Channel Isolation Performance Ground loops and common-mode noise are suppressed via built-in physical isolation barriers. This design prevents field-side electrical anomalies or localized wire shorts from migrating to adjacent measurement paths or disrupting internal analog-to-digital converter sub-components.

Frequently Asked Questions

Q: How does the module react if the transmitter power supply voltage drops below the 14.8 VDC threshold at 20 mA?

A: A voltage drop below operational thresholds prevents proper loop excitation for 2-wire transmitters. The module detects the resulting loop current collapse, tags the associated register data as invalid inside the database, and flags an I/O channel error on the system diagnostics.

Q: Is the ALU4*D module hot-swappable while the DCS I/O node carrier is fully energized?

A: Yes. The hardware includes staged backplane connection pins that manage transient inrush currents. The electronic unit can be removed or inserted under power without interrupting communication on adjacent I/O cards or tripping active process control loops.