Honeywell 2MLI-D24A 32-Point DC 24V Digital Input Module

Product Overview

The Honeywell 2MLI-D24A is a 32-point DC 24V digital input module for the MasterLogic-200 (ML200) PLC system. It supports both sourcing (PNP) and sinking (NPN) input configurations, making it universally compatible with a wide range of sensors, switches, and field devices. With photo-coupler isolation and configurable input filtering, it delivers reliable digital signal acquisition in high-speed manufacturing and process environments.

Key Specifications

• Product Type: 32-Point Digital Input Module
• Series: MasterLogic-200 / ML200
• Input Points: 32
• Rated Input Voltage: DC 24V
• Operating Voltage Range: DC 20.4V to 28.8V (ripple rate <5%)
• Rated Input Current: Approx. 4 mA per point
• Input Type: Source/Sink (configurable)
• On Voltage/Current: DC 19V or higher / 3 mA or higher
• Off Voltage/Current: DC 11V or lower / 1.7 mA or lower
• Input Resistance: Approx. 5.6 kΩ
• Response Time: 1 ms / 3 ms / 5 ms / 10 ms / 20 ms / 70 ms / 100 ms (CPU parameter selectable, default 3 ms)
• Isolation Method: Photo-coupler isolation
• Isolation Voltage: AC 560V rms / 3 cycles (altitude 2000m)
• Common Method: 32 points / 1 COM
• External Connection: 40-point connector
• Current Consumption: 50 mA (from 5V internal bus)
• Dimensions (W x H x D): 27.4 mm x 90 mm x 70 mm
• Weight: Approx. 0.1 kg (100 g)
• Operating Temperature: 0°C to +55°C

Features & Benefits

• 32 high-density inputs in one slot — reduces module count by 50% compared to 16-point designs, lowering hardware cost and cabinet space
• Universal source/sink compatibility — accepts both PNP and NPN sensors without wiring changes or module swaps, simplifying BOM management
• Configurable input filtering — 1 ms to 100 ms response time selection via CPU parameters eliminates chatter from mechanical switches and reduces false counts from contact bounce
• 560V AC isolation — photo-coupler isolation protects the CPU and backplane from field-side voltage transients and ground loops
• Compact 27.4 mm width — high-density packaging enables up to 12 I/O modules in a single 12-slot base

Typical Applications

• Automotive assembly line sensor aggregation (proximity, photoelectric, limit switches)
• Conveyor system position and product detection
• Packaging machinery bag-present and gate-closed sensors
• Water/wastewater pump status and level switch monitoring
• Building automation HVAC fan proof and filter status inputs
• Material handling crane limit and safety interlock inputs

Installation Guide

1. Verify input polarity — confirm whether your field devices are sourcing (PNP) or sinking (NPN) and wire the COM terminal accordingly.
2. Install on de-energized base — align the module with the base connector and press firmly until the retention clips engage.
3. Connect 40-pin field cable — use the Honeywell 40-point connector or terminal block adapter (TG7-1H40S) to wire field devices.
4. Apply 24V DC field power — connect a stable 24V DC supply (20.4–28.8V) to the COM and input terminals.
5. Configure response time — in SoftMaster, set the input filter to 1 ms for high-speed counting or 10–100 ms for mechanical switch debounce.
6. Test each point — activate each sensor and verify the corresponding input LED illuminates and the CPU register updates.

FAQ

Q: What is the difference between 2MLI-D24A and 2MLI-D24B?
A: The 2MLI-D24A supports both source and sink configurations. The 2MLI-D24B is source-type only. The A variant offers greater flexibility; the B variant is lower cost for pure PNP applications.

Q: Can I use this with AC input devices?
A: No. This is a DC 24V input module. For AC inputs (110V or 220V), select 2MLI-A21A or 2MLI-A12A respectively.

Q: What is the maximum number of 2MLI-D24A modules per CPU?
A: The 2MLI-CPUU supports up to 6,144 I/O points. At 32 points per module, you can theoretically install up to 192 modules, limited by power supply capacity and base slot count.

Q: Does this module support interrupt inputs?
A: No. For high-speed interrupt or counter inputs, use the 2MLF-HO2A (pulse input) module or the CPU's built-in high-speed counter functions.

Q: What cable gauge is recommended?
A: Use 0.3–0.75 mm² (22–18 AWG) stranded or solid copper wire. The 40-point connector supports up to 0.75 mm² per pin.

Selection Tips

• Choose 2MLI-D24A when you need 32 DC 24V inputs with mixed PNP/NPN sensor types.
• If your plant uses exclusively PNP (sourcing) sensors, the 2MLI-D24B offers the same density at lower cost.
• For isolated input channels (e.g., mixed-voltage systems), consider the 2MLI-D21D (8-point isolated) instead.
• Always verify your sensor output type before ordering — mixing PNP and NPN on the same COM group will cause input faults.
• Pair with the TG7-1H40S terminal board and C40HF-15PB-1 cable for organized, tool-free field wiring.