Honeywell 2MLF-AD8A 8-Channel Analog Input Module, 14-Bit, 250 μs/Channel

Product Overview

The Honeywell 2MLF-AD8A is an 8-channel analog input module for the MasterLogic-200 PLC series. It converts analog voltage and current signals from field devices into high-resolution digital values. With 14-bit binary resolution (1/16000), 250 μs per channel conversion speed, and ±0.2% accuracy, this module delivers precise and fast data acquisition for critical process control applications.

Key Specifications

• Channels: 8 independent analog input channels
• Input Types: Voltage and current (hybrid input processing)
• Voltage Ranges: 1–5V, 0–5V, 0–10V, -10 to +10V DC
• Current Ranges: 4–20mA, 0–20mA DC
• Resolution: 1/16000 (14-bit binary)
• Voltage Resolution: 0.250mV (1–5V), 0.3125mV (0–5V), 0.625mV (0–10V), 1.250mV (-10 to +10V)
• Current Resolution: 1.0µA (4–20mA), 1.25µA (0–20mA)
• Conversion Speed: 250 μs per channel
• Accuracy: ±0.2% or less (at 25°C ±5°C); ±0.3% or less (at 0°C to 55°C)
• Input Impedance: ≥ 1MΩ (voltage input); 250Ω (current input)
• Digital Output Formats: Unsigned (0–16000), Signed (-8000–8000), Percentile (0–10000), Precise
• Isolation: Photo-coupler isolation between input terminal and PLC power (no channel-to-channel isolation)
• Disconnection Detection: Automatic input disconnection detection for 1–5V and 4–20mA ranges
• Operating Temperature: 0°C to +55°C
• Weight: 0.115 kg

Features & Benefits

1. Hybrid Input Processing: Each of the 8 channels supports both voltage and current inputs, eliminating the need for separate voltage-only or current-only modules.
2. High-Speed Conversion: 250 μs per channel ensures rapid analog signal acquisition, ideal for fast-changing process variables.
3. High Resolution & Accuracy: 14-bit 1/16000 resolution combined with ±0.2% accuracy delivers precise measurement for critical control loops.
4. Flexible Data Formats: Four configurable digital output formats (unsigned, signed, percentile, precise) adapt to diverse programming and HMI requirements.
5. Input Disconnection Detection: Built-in open-circuit detection for 1–5V and 4–20mA inputs enables proactive maintenance and reduces unplanned downtime.
6. Individual Channel Configuration: Each channel's input range and data format can be set independently via DIP switch or SoftMaster I/O parameter settings.

FAQ

Q: Can the 2MLF-AD8A be hot-swapped during operation?
A: No. The module must be inserted or removed only when the controller rack is de-energized to prevent damage to the module or backplane.

Q: Does the 250 μs conversion speed affect the overall PLC scan time?
A: The 250 μs per channel determines how quickly each analog input updates. Overall scan timing depends on the controller's configured I/O strategy and total module count.

Q: Can each channel use a different input range or data format?
A: Yes. Each channel's input type, range, and digital output format can be configured individually through user logic or the SoftMaster I/O parameter interface.

Q: What is the difference between 2MLF-AD8A and 2MLF-AD16A?
A: The 2MLF-AD8A provides 8 channels with 250 μs conversion speed. The 2MLF-AD16A provides 16 channels with 500 μs conversion speed. Select the AD8A for fewer channels and faster conversion, or the AD16A for higher channel density.

Installation Guide

• Install the module into an available slot of a MasterLogic-200 base (main or expansion).
• Wire analog field devices to the module's 18-point terminal block using shielded cables to minimize electrical noise.
• For voltage inputs, connect signal wires to the designated V+ and COM terminals.
• For current inputs, connect the 4–20mA or 0–20mA loop across the I+ and COM terminals.
• Set the input range DIP switches or configure ranges via SoftMaster software before energizing the rack.
• Verify channel status via the module's LED indicators and use the special module monitor function in SoftMaster to confirm correct A/D conversion values.

Selection Tips

• Channel Count vs. Speed: Choose the 2MLF-AD8A for 8 channels at 250 μs speed. If your application requires 16 channels and can tolerate 500 μs conversion, consider the 2MLF-AD16A for higher density.
• Signal Type: The AD8A handles both voltage and current. If your field devices are exclusively voltage or current, the 2MLF-AV8A (voltage only) or 2MLF-AC8A (current only) may offer cost-optimized alternatives.
• Isolation Requirements: The AD8A provides photo-coupler isolation between inputs and PLC power, but not between channels. For applications requiring channel-to-channel isolation, consider the 2MLF-AD4S (4-channel isolated variant).
• HART Protocol: If your 4–20mA devices require HART communication, select the 2MLF-AC4H HART analog input module instead of the standard AD8A.
• Temperature Range: The module operates from 0°C to +55°C. For environments exceeding this range, verify cabinet conditioning or select modules with extended temperature ratings.