Description

Yokogawa AAB841 Analog I/O Module

Configured for signal conversion and loop execution in Yokogawa CENTUM series distributed control systems, the Yokogawa AAB841-S50 (base model AAB841 Analog I/O Module) provides direct electrical interfacing between field instrumentation and controller backplanes. It processes 1-5 V DC differential inputs and drives 4-20 mA outputs within a single slot footprint.

Suffix Breakdown & Model Matrix

Code	Definition
AAB841	Base Model: 8-channel input / 8-channel output, Non-isolated Differential
-S	Standard Type
5	Without explosion protection
0	Basic type

Hardware Specifications

Parameter	Specification
Brand	Yokogawa
Origin	Japan
Weight	0.3 kg
Dimensions	Single Slot Width (Standard DCS Rack)
Operating Temp	0 to 55 degC
Power Consumption	310 mA @ 5 VDC, 250 mA @ 24 VDC
Input Signal	1 to 5 V DC (Non-Isolated Differential)
Output Signal	4 to 20 mA DC
Input Resistance	Power ON: >= 1 MΩ Power OFF: >= 340 kΩ
Allowable Input Voltage	+/- 7.5 V DC
Allowable Common Mode Voltage	+/- 1 V DC or less
Accuracy	Input: +/- 4 mV Output: +/- 48 uA
Data Update Period	10 ms
Step Response Time	Input: 100 ms Output: 40 ms
Temperature Drift	+/- 0.1 % / 10 degC
External Connection	Dedicated KS Cable
HART Communication	Available on Current Input/Output

4-20 mA HART Loop Protocol Integration

The module supports HART protocol communication superimposed on the 4-20 mA current loop. This allows simultaneous transmission of analog process variables and digital device status data over a single pair of wires. The module does not supply transmitter power; external loop power sourcing is mandatory. HART signal integrity requires a minimum loop impedance of 250 ohms for proper modulation detection by the host system.

Frequently Asked Questions

Q: Can this module be hot-swapped while the rack is powered?

A: No. Due to the non-isolated nature of the input channels and the requirement to prevent transient backplane surges, power must be removed from the node before insertion or removal.

Q: What is the impact of common mode voltage exceeding +/- 1 V DC?

A: Exceeding the allowable common mode voltage range will result in input signal clamping and potential damage to the internal A/D conversion circuitry. Ensure field wiring reference grounds are within specified limits.

Q: Is galvanic isolation provided between channels?

A: No. The AAB841 is a non-isolated module. Channel-to-channel isolation is not present; all inputs share a common reference plane.

Field Installation Guidelines

Install the module into the designated DCS I/O slot ensuring the ejector levers fully seat the connector pins. Use only the specified KS cable for field termination. For HART-enabled loops, ensure shield drain wires are terminated at a single point to the cabinet ground bus to prevent ground loops. Verify that the external 24 VDC power supply for the current loops is stable and free of ripple before energizing the module. Do not exceed the maximum backplane current draw of 310 mA at 5 VDC.

Specifications

• Brand: Yokogawa

Advantages

• High reliability in industrial environments
• Supports continuous operation
• Compatible with major PLC/DCS systems