2MLF-AC4H | Honeywell | HART Analog Input Module

Honeywell 2MLF‑AC4H HART Analog Input Module

Configured for HART‑enabled analog acquisition in HC900/ControlEdge networks, the Honeywell 2MLF‑AC4H (2MLF‑AC4H HART analog input module) provides direct multi‑channel current/voltage measurement with integrated HART digital signal extraction across the backplane.

Hardware Specifications

4‑20 mA HART Loop Protocol and Channel Isolation Behavior

The 2MLF‑AC4H is designed specifically for 4‑20 mA HART loop acquisition. The module extracts both the analog process variable and the HART digital secondary variables. Internal architecture uses photo‑coupler isolation between input terminals and PLC power, while HC900 I/O maintains channel‑to‑channel isolation at the system level to prevent cross‑loop interference. This ensures stable HART communication even under mixed analog/HART channel configurations.

Frequently Asked Questions

Q: Can the 2MLF‑AC4H be hot‑swapped during operation? A: No. The module must be inserted or removed only when the controller rack is de‑energized.

Q: Does HART communication affect analog scan timing? A: Analog values update at standard module conversion speed. HART digital variables update at slower, protocol‑defined intervals without affecting analog refresh.

Q: Can each channel operate as non‑HART analog input? A: Yes. Channels can be configured for standard analog measurement when HART extraction is not required.

Field Installation Guidelines

• Use shielded twisted‑pair wiring for HART loops and bond shields at a single termination point.
• Avoid routing HART wiring near high‑frequency digital outputs to reduce electromagnetic coupling.
• Verify loop impedance and device polling configuration before commissioning.
• Ensure proper seating of the terminal block before energizing the rack.
• Maintain loop current within the module’s supported analog input range.