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NSF-61
D20 Display & Controller
Multi-channel display and controller for all Halogen MP-series sensors. Real-time monitoring with 4-20mA outputs, digital communication, SD card logging, and alarm relay — in an IP65 weather-sealed enclosure.
4-20mAModbus RTUCellularEthernet/IPBACnetModbus TCPSD CardIP65
NSF-61verifiedETL (UL/CSA)
radio_button_checkedFCC Part 15
Quick Answer
What is the Halogen D20 controller?
The D20 is a multi-channel display and controller for Halogen MP-series chlorine sensors. It auto-detects the connected sensor, outputs 4–20 mA and Modbus RTU as standard, and supports optional cellular (LTE-M/NB-IoT), Ethernet/IP, BACnet, or Modbus TCP for remote and SCADA integration.
Configure Your D20
Every D20 starts from the same base controller. Add the communication board your network needs, then choose any configuration options.
Step 1 · Base
settings_input_component
D20 Base Controller
The standard controller behind every configuration — works with any Halogen MP-series sensor.
- check_circleColor LCD display with real-time trend graphs
- check_circleFour 4-20mA analog outputs
- check_circleModbus RTU (RS-485) standard — the bus used to communicate with MP-series sensors
- check_circleSD card data logging (CSV)
- check_circleConfigurable alarm relay output
- check_circleAutomatic MP-series sensor detection
- check_circleIP65 weather-sealed enclosure
Step 2 · Connectivity
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Add a Communication Board
Feeding a SCADA, BMS, or cloud platform? Add one selectable daughter board for digital connectivity.
CellularEthernet/IPBACnetModbus TCP
Compare communication boardsarrow_downwardStep 3 · Options
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Choose Configuration Options
Optional build variants for specific regions and use cases.
- verifiedCE Marked (D20 CE) — for European Union installations; meets EU EMC and safety directives.
- tvDisplay Only (D20 Display) — a 24VDC display unit without controller functions, for read-only monitoring.
Communication Add-Ons
Communication Daughter Boards
Every D20 ships with four 4-20mA analog outputs. To connect to a digital network, add a single selectable daughter board — pick the one that matches your infrastructure.
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Cellular
LTE-M / NB-IoT wireless
Built-in LTE-M / NB-IoT modem for remote sites with no wired network — streams readings to a cloud dashboard from anywhere. Available in North America (D20-OTA) and Europe/MEA (D20-OTA-EU) carrier configurations.
lan
Ethernet/IP
Industrial Ethernet
EtherNet/IP connectivity for integration with Allen-Bradley / Rockwell PLCs and SCADA systems over a standard Ethernet network.
hub
BACnet
Building automation
BACnet integration for building management systems (BMS) — brings chlorine, pH, and temperature data straight into HVAC and facility monitoring platforms.
device_hub
Modbus TCP
Modbus over Ethernet
Modbus TCP for PLC and SCADA integration over Ethernet — a widely supported industrial protocol for plant-wide monitoring and control.
One communication daughter board can be installed per controller, in addition to the standard 4-20mA outputs. Not sure which fits your system? Talk to our team and we'll help you configure it.
Key Features
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Multiparameter Monitoring
Displays all sensor readings simultaneously — chlorine, pH, conductivity, temperature, and ORP — with real-time trend graphs.
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User-Friendly Interface
Easy configuration and calibration via the color display. Arrow-key navigation makes setup intuitive for field operators.
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Automatic Sensor Detection
Plug in any Halogen MP-series sensor and the D20 automatically detects the sensor type and configures parameters.
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IP65 Rated Enclosure
Weather-sealed enclosure rated for outdoor and wet installations. Withstands washdowns, rain, and harsh environments.
sd_card
SD Card Data Logging
Built-in SD card slot for continuous data logging. Export CSV data for compliance reporting and trend analysis.
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Alarm Relay Output
Configurable high/low alarm thresholds with dry-contact relay output. Trigger external devices or send notifications on exceedances.
See the display. Plan the connection.
Installation Guide
Five steps from unboxing to real-time monitoring.
01
Plan & Confirm Requirements
Verify power availability (120VAC or 240VAC). Gather tools: #2 Phillips & flathead screwdrivers. Confirm box contents: D20 controller, sensor, mounting tabs, cables, and guide.
02
Mount the Controller
Wall mount using included tabs and screws, or pole mount on 0.75″–2.5″ diameter pipe. Ensure unit is upright and level with 6.3″ clearance for the display door.
03
Connect Power & Wiring
Wire 120V/240V power input, 4-20mA outputs to PLC, optional alarm relay, and optional flow sensor. Connect sensor via M12 connector.
04
Install Sensor
Install the MP-series sensor into the flow cell or wet-tap fitting. Position sensor outlet vertically to purge air. Limit inlet pressure to 60 PSI.
05
Power Up & Commission
Plug in power, confirm water flow, and monitor D20 startup status. Configure 4-20mA output scaling and communication settings via the display.
Technical Specifications
| Specification | Value |
|---|---|
| Display | Color LCD with backlight |
| Power Input | 120VAC or 240VAC (model dependent) |
| Analog Outputs | 4× 4-20mA (configurable) |
| Digital Communication | Modbus RTU (RS-485) standard on every D20 (sensor bus); optional daughter board adds Cellular (LTE-M/NB-IoT), Ethernet/IP, BACnet, or Modbus TCP |
| Data Logging | SD card (CSV format) |
| Alarm Output | Dry-contact relay (configurable thresholds) |
| Sensor Connection | M12 4-pin connector (Modbus RTU / RS-485 sensor bus) |
| Enclosure Rating | IP65 |
| Mounting | Wall mount or pole mount (0.75″–2.5″ diameter) |
| Certifications | NSF/ANSI/CAN 61 & 372, FCC Part 15 Class A, ETL (UL/CSA) |
| Operating Temperature | 0°C to 50°C (32°F to 122°F) |
Compatible Sensors
The D20 controller works with all Halogen MP-series sensors via the M12 connector.
D20 + MP-5F Free Chlorine product guide
Updated R1.18 guide, with earlier manuals available for existing equipment.
View the MP-5F guide — R1.18Download the D20 Data Sheet
Get full technical specs, wiring diagrams, communication protocols, and dimensional drawings.
Frequently Asked Questions
What chlorine analyzer works with Modbus, BACnet, or 4–20 mA?
The Halogen D20 controller outputs 4–20 mA and Modbus RTU (RS-485) as standard, with optional daughter boards for Modbus TCP, BACnet, and Ethernet/IP, plus cellular (LTE-M/NB-IoT) for remote sites. This lets MP-series chlorine sensors integrate directly with SCADA, BMS, and AMI systems.
Need help choosing a controller?
Our team can recommend the right D20 variant for your SCADA system, BMS, or remote monitoring setup.
Plan the system and record the result.
Field checklists
Prepare a pilot, wet-tap installation, D20 integration or remote site. Download a blank pilot record.
Use the checklists →Certifications and manuals
Check the exact model, assembly, firmware and certification scope before specifying a system.
Review certifications →DISCUSS YOUR APPLICATION
Review your monitoring point with Halogen.
Bring your water chemistry, installation requirements and questions about the right configuration.
Book a meeting with a Halogen team member