Honeywell 2MLF-DC8A 8 Channel Current Output Module

Product Overview

The Honeywell 2MLF-DC8A is an 8-channel analog current output module for the MasterLogic-200 (ML200) programmable logic controller system. It provides high-resolution current output signals to field actuators, valves, and drives, supporting both 4–20 mA and 0–20 mA selectable ranges per channel. Designed for process control and factory automation, it delivers reliable signal conversion with built-in isolation and diagnostic capabilities.

Key Specifications

• Product Type: 8-Channel Analog Current Output Module
• Series: MasterLogic-200 / ML200
• Output Type: Current (DC 4–20 mA / DC 0–20 mA, selectable per channel)
• Number of Channels: 8
• Load Resistance: ≤ 550 Ω
• Resolution: 16-bit
• Isolation: Photo-coupler isolation between channel and internal logic
• Conversion Speed: 4 ms / 8 channels
• Accuracy: ±0.1% FS at 25°C
• External Power Supply: DC 24V (20.4–28.8V)
• Current Consumption: 60 mA (from 5V internal bus)
• External Connection: 20-point removable terminal block
• Dimensions (W x H x D): 27.4 mm x 90 mm x 70 mm
• Weight: Approx. 110 g
• Operating Temperature: 0°C to +55°C
• Storage Temperature: -25°C to +70°C
• Relative Humidity: 5% to 95% RH (non-condensing)

Features & Benefits

• 8-channel high-density design — reduces panel footprint by 40% compared to 4-channel modules, saving valuable DIN rail space in compact control cabinets
• Selectable 4–20 mA or 0–20 mA per channel — software-configurable output range eliminates the need for separate modules, reducing spare parts inventory
• 16-bit resolution — provides 0.0015% precision for fine control of valve positioners and variable speed drives
• Photo-coupler isolation — 560 V AC isolation protects CPU and communication modules from ground loops and field-side surges
• Fast 4 ms conversion — meets the response requirements of fast-acting process loops such as flow and pressure control
• Removable terminal block — enables pre-wiring and hot-swapping during maintenance without disturbing adjacent modules

Typical Applications

• Petrochemical refinery valve positioner control
• Water treatment chemical dosing pump control
• HVAC variable air volume (VAV) damper actuators
• Food & beverage pasteurization temperature control loops
• Pharmaceutical batch reactor pressure control
• Power plant boiler feedwater valve modulation

Installation Guide

1. Verify slot compatibility — the 2MLF-DC8A occupies one I/O slot in any ML200 main base (2MLB-MxxA) or expansion base (2MLB-ExxA).
2. Install on de-energized base — align the module with the base connector and press firmly until the retention clips click.
3. Connect 24V DC external power — wire the external supply (20.4–28.8V DC) to the designated power terminals on the removable terminal block.
4. Wire field devices — connect actuators and valve positioners to the output channels using shielded twisted-pair cable. Maintain proper polarity.
5. Configure output range — use SoftMaster programming software to select 4–20 mA or 0–20 mA per channel and set hold-last or preset values for CPU fault conditions.
6. Verify output calibration — use a precision multimeter to confirm each channel outputs exactly 4.000 mA at 0% command and 20.000 mA at 100% command.

FAQ

Q: What is the difference between 2MLF-DC8A and 2MLF-DC8A-CC?
A: The -CC suffix indicates a conformal coated version for harsh environments (high humidity, corrosive atmospheres). The base 2MLF-DC8A is standard grade. Electrical specifications are identical.

Q: Can I use this module with the ML200R redundant system?
A: Yes. The 2MLF-DC8A is compatible with both ML200 (non-redundant) and ML200R (redundant) systems when installed in the appropriate I/O base.

Q: What is the maximum cable length to the field device?
A: With a maximum load of 550 Ω, the loop can support approximately 1,000 meters of 0.75 mm² cable, depending on the receiver impedance and supply voltage.

Q: Does this module support HART protocol?
A: No. For HART-enabled current output, select the 2MLF-DC4H (4-channel HART output) module instead.

Q: What happens to outputs during CPU stop or power loss?
A: Outputs can be configured via SoftMaster to hold last value, reset to zero, or go to a preset value during CPU fault or power cycle conditions.

Selection Tips

• Choose 2MLF-DC8A when you need 8 channels of current output in a single slot for high-density analog control.
• If your application requires HART communication over the 4–20 mA loop, downgrade to 4 channels and select 2MLF-DC4H.
• For voltage output (0–10V) to servo drives or VFDs, select 2MLF-DV8A instead.
• In marine, coastal, or chemical plant environments, specify the -CC conformal coated variant for enhanced corrosion resistance.
• Verify your actuator load resistance is ≤550 Ω; higher loads will cause output current errors and potential module fault alarms.