Introduction
In outdoor industrial IoT scenarios, wireless DTUs face extreme challenges: rain immersion, scorching sun, freezing cold, and sand invasion. The traditional "add a waterproof box" solution not only increases costs but also compromises antenna signals and installation convenience.
EBYTE launches three IP67 waterproof LoRa wireless DTUs — E91-DTU(400SL30), E91-DTU(900SL30), and E91-DTU(400SL37) — purpose-built to solve this core pain point: making wireless communication fearless in any weather.
Product Overview
The E91-DTU series is a new generation of LoRa waterproof wireless DTUs based on SEMTECH's high-performance RF chips, featuring IP67-rated waterproof plastic housing, silicone O-ring sealing, and internal resin potting to withstand short-term immersion and prolonged rain exposure.
| Model | Frequency Band | Max Tx Power | Reference Range | Core Positioning |
|---|---|---|---|---|
| E91-DTU(400SL30) | 410~493 MHz | 30dBm (1W) | 8 km | Cost-effective waterproof主力, 433MHz long range & strong penetration |
| E91-DTU(900SL30) | 850~930 MHz | 30dBm (1W) | 8 km | 868/915MHz international frequency band waterproof solution |
| E91-DTU(400SL37) | 410~493 MHz | 37dBm (5W) | 25 km | Ultra-long-range waterproof flagship, extreme coverage |
Key Selling Points
IP67 Waterproof & Dustproof: Submersible in 1m water for 30 minutes, no external enclosure needed
Industrial Wide Temperature: -40°C ~ +85°C, suitable from the Arctic to the desert
Wide Voltage Input: 8~28V DC (10~28V for 400SL37), compatible with solar panels, batteries, etc.
RS485 Interface: M12 waterproof aviation connector, simple and reliable
Features and Model Comparison
Common Features Across All Three Models
| Feature | Description |
|---|---|
| IP67 Waterproof | Flame-retardant plastic housing + silicone O-ring seal + internal resin potting, triple protection |
| High Power Output | 400SL30/900SL30: 30dBm (1W); 400SL37: 37dBm (5W) |
| Wide Voltage Supply | 8~28V DC (400SL37: 10~28V) |
| Dual Command System | Supports both HEX commands and AT commands |
| Multiple Operating Modes | Transmission mode (transparent), WOR mode (wake-on-air), configuration mode, sleep mode |
| Relay Networking | Supports multi-level relaying for ultra-long-distance communication |
| Communication Encryption | User-defined encryption key, unreadable, ensuring data security |
| LBT Function | Listen Before Talk, improves communication success in harsh environments |
| RSSI Indication | Real-time signal quality assessment |
| Wireless Configuration | Supports remote wireless parameter configuration |
| Modbus Protocol | Supports Modbus RTU protocol transparent transmission |
Model Comparison
| Dimension | E91-DTU(400SL30) | E91-DTU(900SL30) | E91-DTU(400SL37) |
|---|---|---|---|
| Frequency Band | 410~493 MHz | 850~930 MHz | 410~493 MHz |
| Default Frequency | 433.125 MHz | 868.125 MHz | 433.125 MHz |
| Max Tx Power | 30dBm (1W) | 30dBm (1W) | 37dBm (5W) |
| Reference Range | 8 km | 8 km | 25 km |
| Supply Voltage | 8~28V DC | 8~28V DC | 10~28V DC |
| Tx Current @12V | 250~300 mA | 360~430 mA | 1100~1300 mA |
| Rx Current @12V | ≈16 mA | ≈15 mA | ≈60 mA |
| Operating Temp | -40°C ~ +85°C | -40°C ~ +85°C | -40°C ~ +85°C |
| Waterproof Rating | IP67 | IP67 | IP67 |
| Dimensions | 90×53×42 mm | 90×53×42 mm | 120×75×48 mm |
| Antenna Type | SMA-K (male, internal bore) | SMA-K (male, internal bore) | SMA-K (male, internal bore) |
| Interface | M12 5-pin waterproof (RS485) | M12 5-pin waterproof (RS485) | M12 5-pin waterproof (RS485) |
| Air Data Rate | 2.4K~62.5Kbps | 2.4K~62.5Kbps | 0.3K~62.5Kbps |
Selection Guide
| Scenario | Recommended Model | Reason |
|---|---|---|
| China market, general outdoor waterproof communication | E91-DTU(400SL30) | 433MHz offers strong penetration, 30dBm covers 8km, best value for money |
| European/North American market, international frequency needs | E91-DTU(900SL30) | Supports 868/915MHz international ISM bands, compliant with local regulations |
| Ultra-long-distance communication (15km+) | E91-DTU(400SL37) | 5W high power delivers 25km extreme range, designed for wide-area coverage |
Technical Specifications
Core RF Parameters
| RF Parameter | E91-DTU(400SL30) | E91-DTU(900SL30) | E91-DTU(400SL37) |
|---|---|---|---|
| Modulation | Next-gen LoRa modulation | Next-gen LoRa modulation | Next-gen LoRa modulation |
| Frequency Band | 410~493 MHz | 850~930 MHz | 410.125~493.125 MHz |
| Tx Power | 30dBm (1W) | 30dBm (1W) | 37dBm (5W) |
| Rx Sensitivity | -132dBm @2.4kbps SF11 | -132dBm @2.4kbps SF11 | -132dBm @2.4kbps SF11 |
| Air Data Rate | 2.4K~62.5Kbps | 2.4K~62.5Kbps | 0.3K~62.5Kbps |
| Reference Range | 8 km | 8 km | 25 km |
| Antenna Type | SMA-K (male, internal bore, 50Ω) | SMA-K (male, internal bore, 50Ω) | SMA-K (male, internal bore, 50Ω) |
| Interface | RS485 (M12 5-pin) | RS485 (M12 5-pin) | RS485 (M12 5-pin) |
| Tx Packet Length | 240 Bytes (configurable) | 240 Bytes (configurable) | 240 Bytes (configurable) |
| Buffer Capacity | 1000 Bytes | 1000 Bytes | 1000 Bytes |
Electrical Parameters
| Electrical Parameter | E91-DTU(400SL30) | E91-DTU(900SL30) | E91-DTU(400SL37) |
|---|---|---|---|
| Supply Voltage | 8~28V DC | 8~28V DC | 10~28V DC |
| Tx Current @12V | 250~300 mA | 360~430 mA | 1100~1300 mA |
| Rx Current @12V | ≈16 mA | ≈15 mA | ≈60 mA |
| Operating Temp | -40°C ~ +85°C | -40°C ~ +85°C | -40°C ~ +85°C |
| Waterproof Rating | IP67 | IP67 | IP67 |
| Dimensions | 90×53×42 mm | 90×53×42 mm | 120×75×48 mm |
Factory Default Parameters
| Model | Default Freq | Default Address | Default Channel | Default Air Rate | Default Baud | Default Serial Format | Default Power |
|---|---|---|---|---|---|---|---|
| E91-DTU(400SL30) | 433.125 MHz | 0x0000 | 0x17 | 2.4kbps | 9600 | 8N1 | 30dBm |
| E91-DTU(900SL30) | 868.125 MHz | 0x0000 | 0x12 | 2.4kbps | 9600 | 8N1 | 30dBm |
| E91-DTU(400SL37) | 433.125 MHz | 0x0000 | 0x17 | 2.4kbps | 9600 | 8N1 | 37dBm |
Application Scenarios
Scenario ①: Smart Agriculture Irrigation & Environmental Monitoring
Pain Point: Sensors and control valves are scattered across vast farmlands, frequently exposed to rain and direct irrigation spray. Equipment must be fully waterproof.
Solution: The E91-DTU(400SL30)'s IP67 waterproofing and wide temperature range allow it to be mounted on concrete poles in the field. Its 8km communication range covers large farm areas without requiring relays.
Scenario ②: Photovoltaic Power Station Monitoring
Pain Point: Solar panel arrays are exposed to direct sunlight, with surface temperatures reaching 70°C in summer and dropping to -30°C in winter. Equipment must withstand extreme temperature differences and provide rain and dust protection.
Solution: The E91-DTU(400SL30)'s wide temperature range is a perfect fit, and its wide voltage input (8~28V) adapts well to solar panel + battery power supply.
Scenario ③: Water Source & Pump Station Monitoring
Pain Point: Equipment is installed in humid well houses, along riverbanks, or near reservoirs with extremely high humidity and continuous moisture erosion risk.
Solution: IP67 resin-potting waterproofing ensures moisture cannot penetrate the internal circuitry. The 5W version (400SL37) covers the ultra-long distance of 25km from water sources to control centers.
Scenario ④: Building Automation & Heating Network Monitoring
Pain Point: Sensors are deployed in underground utility tunnels and damp shaft pits — harsh environments with difficult maintenance access.
Solution: The E91-DTU(900SL30) is ideal for European and American markets, with its compact size (90×53×42mm) facilitating installation in narrow shaft spaces.
Scenario ⑤: Urban Waterlogging Level Monitoring
Pain Point: Equipment is installed in low-lying areas near drainage outlets and may be briefly submerged by rainwater.
Solution: IP67-rated protection allows the DTU to continue normal communication even after short-term underwater immersion — a perfect fit for waterlogging monitoring scenarios
EBYTE Core Advantages
| Advantage | Description |
|---|---|
| IP67 Waterproof + Industrial Wide Temp | No external waterproof enclosure needed; install directly outdoors, significantly reducing installation cost and complexity |
| M12 Waterproof Aviation Connector | The connection port is also waterproof, ensuring seamless overall protection |
| Dual Command System + Multiple Modes | Supports HEX and AT command systems; four operating modes for flexible switching |
| Relay Networking + Communication Encryption | Multi-level relay, multiple independent networks in the same area; custom encryption key for data security |
| Complete Product Portfolio | 400SL30 (1W/8km), 900SL30 (1W/8km/international), 400SL37 (5W/25km) — covering all range requirements |
| Comprehensive Documentation | Datasheet, user manual, AT command list, register configuration, antenna recommendations, FAQ — full technical documentation suite |
FAQ
Q1: The actual transmission distance is far below the rated value. What should I do?
The rated distances (8km/25km) are measured under ideal conditions (clear open area, antenna at 2.5m height, 2.4kbps air rate, high-gain antenna). Factors causing real-world attenuation include:
Obstacles: Trees, buildings, and terrain significantly attenuate signals; 900MHz has weaker diffraction capability
Antenna Quality: Use high-quality, high-gain antennas (5dBi or higher); avoid metal obstructions near the antenna
Supply Voltage: Ensure voltage is within the recommended range; low voltage reduces transmission power
Air Data Rate: Lower rates (e.g., 2.4kbps) deliver longer distances
Antenna Height: Increasing installation height effectively extends communication range
Q2: How to wire correctly? What are the 485_A and 485_B pin assignments?
M12 5-pin aviation connector wire color definition:
| Wire Color | Definition |
|---|---|
| Red | VCC Power Positive (8~28V DC) |
| Black | GND Power Negative |
| Yellow | RS485 Signal A (485-A) |
| White | RS485 Signal B (485-B) |
| Green | PE Ground |
If communication issues occur when connecting multiple devices but not with a single device, connect a 120Ω termination resistor in parallel between 485_A and 485_B.
Q3: Communication issues with multiple devices — how to troubleshoot?
Check wiring: Confirm 485_A and 485_B are not reversed
Check parameters: Verify air data rate, network ID (NETID), channel, and communication key are consistent across all devices
Check address: Module addresses should match; set to FFFF for broadcast (no address filtering)
Termination resistor: A 120Ω resistor is required on the 485 bus
Power quality: Check for ripple; use a regulated power supply
Q4: How to enter configuration mode?
Mode switching via AT commands:
| Command | Mode | Description |
|---|---|---|
AT+MODE=0 | Transmission mode | Transparent transmission, factory default |
AT+MODE=1 | WOR mode | Supports wake-on-air |
AT+MODE=2 | Configuration mode | Access registers via serial port |
AT+MODE=3 | Deep sleep mode | Minimum power consumption |
Q5: What are the main differences between E91-DTU(400SL30) and E91-DTU(400SL37)?
| Item | 400SL30 | 400SL37 |
|---|---|---|
| Tx Power | 30dBm (1W) | 37dBm (5W) |
| Supply Voltage | 8~28V DC | 10~28V DC |
| Reference Range | 8 km | 25 km |
| Dimensions | 90×53×42 mm | 120×75×48 mm |
| Tx Current @12V | 250~300 mA | 1100~1300 mA |
| Application | General outdoor communication | Ultra-long-distance extreme coverage |
Q6: How to configure the channel?
400 MHz band:
AT+CHANNEL=<ch>, ch range 0~83, actual frequency = 410.125 + ch × 1MHz900 MHz band:
AT+CHANNEL=<ch>, ch range 0~80, actual frequency = 850.125 + ch × 1MHz
Q7: How to choose the air data rate?
Set via AT+RATE=<rate> command. Supports 2.4K~62.5Kbps (400SL37 supports 0.3K~62.5Kbps).
Distance priority → Choose a lower rate (e.g., 2.4Kbps) for maximum range
Throughput priority → Choose a higher rate (e.g., 62.5Kbps) for minimum latenc
The E91-DTU(400SL30/900SL30/400SL37) series is Ebyte's purpose-built IP67 waterproof LoRa DTU family for harsh outdoor environments. With "waterproof design without an external enclosure" as its core differentiator, combined with industrial-grade features such as wide temperature range, wide voltage input, and high power output, it precisely solves the critical pain point of "harsh outdoor wireless communication environments" in agriculture, solar energy, water management, and industrial parks.
