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LT312
LoRaWAN-DTU

LT312 is a general-purpose LoRaWAN data terminal supporting OTAA/ABP and Class A/C with ADR or fixed SF. It enables Modbus-RTU acquisition, remote commands, and data upload via RS485/RS232.

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Serial Acquisition & Transparent Transfer over LoRaWAN

Fully isolated serial ports
Fully isolated RS232/RS485 with strong ESD protection improves reliability in noisy environments.
Flexible LoRaWAN modes
OTAA/ABP and Class A/C with ADR or fixed SF for balanced coverage, power and capacity.
Adjustable RF & data rates
Multi-SF options and typical rate ranges fit varying distance and power objectives.
Transparent & active acquisition
Supports transparent transfer and scheduled/active polling, including Modbus-RTU structured reads.
Multi-region bands coverage
Supports multiple regional frequency plans for cross-region deployments.
Task orchestration & stability
Configurable acquisition/heartbeat tasks with watchdog mechanisms improve long-term maintainability.
  • Core Technical Specifications
    Adaptive and Link Control Supports ADR and fixed SF switching, with adjustable channels and transmit power
    Automation and Task Capabilities Supports script editing, scheduled tasks, and active polling
    Cloud Integration Capability End-to-cloud data forwarding through LoRaWAN gateways/platforms
    Device Operating Modes Class A/C, supports OTAA and ABP
    Frequency Bands and RF Coverage EU433/CN470/CN779/EU868/AS923/AU915/KR920
    Humidity and Status Indicators 5 to 95% RH (non-condensing); includes POWER/RUN/LoRa/RS232/RS485 indicators
    LoRaWAN Protocol and Version LoRaWAN 1.0.3
    Power Consumption and Environmental Adaptability Average power consumption <= 0.5 W; operating temperature -20 to 70 C, storage temperature -40 to 85 C
    Power Input and Connectors DC12V/1A; supports 3.81 mm terminal and DC 5.5 x 2.1 mm power port
    Serial Data Services Transparent transmission, compatible with Modbus-RTU polling and commands
    Serial Interfaces and Protection 1 x RS232 (DB9) + 1 x RS485 (3.81 mm 2-pin), fully isolated with built-in 15 kV ESD protection
    Transmit Power and Receiver Sensitivity Up to 22 dBm transmit power, -135 dBm sensitivity @ SF12/BW125kHz
  • LoRaWAN RF
    Data rate (typical) 5.5 / 3.1 / 1.8 / 1.0 / 0.6 / 0.3 kbps
    Frequency bands EU433, CN470, CN779, EU868, AS923, AU915, KR920
    Join/operation modes OTAA/ABP, Class A/C
    Protocol LoRaWAN 1.0.3
    Receiver sensitivity -135 dBm @ SF12 BW125kHz
    Spreading factor SF7-SF12, 6 levels adjustable
    Transmit power 22 dBm
  • Serial Interfaces
    RS232 baud rate 2400-115200 bps, default 115200 bps, 8N1
    RS232 protection Fully isolated, built-in 15 kV ESD
    RS232 quantity/type 1 x DB9
    RS485 baud rate 2400-115200 bps, default 9600 bps, 8N1
    RS485 protection Fully isolated, built-in 15 kV ESD
    RS485 quantity/type 1 x 3.81 mm 2-pin terminal
  • Power
    Connector type Port 1: 3.81 mm 2-pin terminal; Port 2: DC 5.5 x 2.1 mm
    Input DC12V, 1A
    Power Consumption Average <= 0.5 W
  • Mechanical & Environment
    Ambient humidity 5 to 95% (non-condensing)
    Operating Temperature -20 to 70 C
    Storage temperature -40 to 85 C
  • Indicators
    LoRa indicator On: LoRa data transmitting; Off: idle
    POWER indicator On: normal power; Off: undervoltage or fault
    RS232 indicator Blinks: RS232 data received; Off: idle
    RS485 indicator Blinks: RS485 data received; Off: idle
    RUN indicator Blinks: normal operation; steady on/off: fault
  • Network Features
    Channel/power control Adjustable channel and transmit power
    Device class Class A/C
    Join method OTAA / ABP
    Link adaptation ADR and fixed SF switching
    Protocol stack LoRaWAN 1.0.3
  • Serial Data Services
    Data mode Transparent transmission
    Protocol compatibility Modbus-RTU compatible polling/commands
    Serial configuration Flexible serial settings for diverse devices
    Task scheduling Scheduled tasks and active polling
  • Automation & Reliability
    Heartbeat Customizable LoRaWAN heartbeat
    I/O output control Configurable output behavior
    Script support Script editing and task orchestration
    Watchdog Built-in reliability watchdog
  • Deployment & Integration
    Cloud path End-to-cloud data forwarding via LoRaWAN gateway/platform
    Device integration Meters, PLCs, and serial devices
    Typical scenarios Buildings, campuses, factories
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Standard package*

  • LT312 LoRaWAN-DTU *1
  • LoRaWAN Antenna *1
  • Power Supply *1
  • Expansion Bolt *5

* Standard package contents vary by standard order codes.

Contact us directly to learn more about our packaging options.

Frequently Asked Questions

What does the LT312 offer?

The LT312 is an industrial LoRaWAN Data Terminal Unit (DTU) — a serial-to-LoRaWAN bridge that lets RS232 / RS485 devices (meters, PLCs, controllers) talk to a LoRaWAN network without any additional infrastructure. Highlights:

——
LoRaWANLoRaWAN 1.0.3; OTAA or ABP join; Class A or Class C
RFTX power 22 dBm; RX sensitivity −135 dBm @ SF12 / 125 kHz; SF7–SF12 (ADR or fixed); 125 kHz BW
Data rates5.5 / 3.1 / 1.8 / 1.0 / 0.6 / 0.3 kbps (SF7 → SF12)
Serial1× RS485 (3.81 mm 2-pin terminal) + 1× RS232 (DB9) — both fully isolated with 15 kV ESD protection
Baud rates2400 – 115200 bps; default RS485 = 9600, RS232 = 115200; 8N1
ProtocolModbus-RTU compatible polling; transparent transmission; scheduled or remote commands
ScriptingScript editing + task orchestration for custom acquisition logic; configurable LoRaWAN heartbeat
ReliabilityHardware watchdog
PowerDC 9–28 V wide input, average ≤ 0.5 W; ships with 12 V adapter and wall-mount kit
Antenna1× SMA
Environment−20 to +70 °C operating
LEDs5× — POWER, RUN, LoRa, RS232, RS485

Four regional SKUs by LoRaWAN frequency plan:

SKUFrequency planRegion
———
LT312-US915US915North America
LT312-EU868EU868Europe
LT312-CN470CN470China
LT312-AS923AS923Asia-Pacific (excluding South Korea and India)

The spec also lists support for EU433 / CN779 / AU915 / KR920 bands; contact InHand for availability of those regional variants.

Target applications per the datasheet: buildings, campuses, and factories — simplifying integration of meters, PLCs, and serial devices into LoRaWAN networks.

  1. Mount the LT312 using the included wall-mount kit, or place on a desk.
  2. Connect the antenna to the SMA connector. Keep it elevated and away from metal surfaces for best range.
  3. Connect the serial device:
  • RS485 — wire A and B to the 3.81 mm 2-pin terminal block.
  • RS232 — connect via the DB9 port.
  1. Power up with the supplied 12 V adapter (DC 5.5 × 2.1 mm barrel jack), or wire your own DC 9–28 V source to the 3.81 mm 2-pin power terminal block.
  2. Verify status via the five LEDs:
  • POWER solid = power normal; off = under-voltage or fault.
  • RUN blinking = system running normally; constantly on or off = fault.
  • LoRa on = LoRa data is transmitting; off = no LoRa data.
  • RS232 / RS485 blinking = serial data being received on that port.

The LT312 supports four data-flow modes that can be combined to fit the deployment:

  • Transparent transmission — anything received on RS232 or RS485 is passed straight to the LoRaWAN uplink (and vice versa for downlinks). Useful when the upstream application already speaks the device’s native protocol.
  • Active polling (Modbus-RTU) — the LT312 polls the connected meter / PLC / controller at configurable intervals using Modbus-RTU and forwards the readings as LoRaWAN uplinks.
  • Scheduled commands — pre-configured serial commands are sent on a fixed schedule (for example, an hourly meter read or a daily reset).
  • Remote commands — downlink commands from the LoRaWAN network server are relayed onto the serial port (push a control command from the cloud to a downstream device).

For more complex behavior, script editing + task orchestration lets you compose acquisition tasks, define their execution order and schedule, and customize the LoRaWAN heartbeat payload and interval. The hardware watchdog auto-recovers from faults.

LoRaWAN-stack settings are configurable: OTAA or ABP join, Class A (low-power, RX-window-after-TX-only) or Class C (continuous receive for low-latency downlinks), ADR on or fixed SF (SF7–SF12), TX power, and channel plan.

The LT312 (terminal node) and EC312-LoRaWAN (gateway / concentrator) form a complete InHand LoRaWAN stack:

“
Serial device ──RS232/RS485──> LT312 ──LoRaWAN──> EC312-LoRaWAN ──Cellular/Wi-Fi/Ethernet──> Cloud
(meter, PLC, (terminal (gateway with (DeviceLive,
controller) node / DTU) built-in ChirpStack AWS, Azure,
or Packet Forward) ChirpStack, etc.)
“

Match the frequency plan between the two — the LT312 SKU and the EC312-LoRaWAN SKU must use compatible bands (e.g., LT312-US915 with EC312-H-FQ33-L915, or LT312-EU868 with EC312-H-FQ53-L868). Then on the EC312-LoRaWAN gateway, follow the ChirpStack onboarding steps from EC312-LoRaWAN Q3:

  1. In ChirpStack, create the Device Profile matching the LT312’s MAC version (LoRaWAN 1.0.3) and regional parameters.
  2. Create an Application to scope the LT312 nodes.
  3. Add the LT312 as a Device, entering the LT312’s Device EUI, Join EUI, and Application Key (provided by the LT312 / read from its config).
  4. Configure the LT312 itself for OTAA join (matching the application key) or ABP (matching the device address and session keys), and choose Class A or Class C per your downlink-latency needs.
  5. Trigger serial traffic on the LT312 — uplinks appear in the ChirpStack Events tab; for Class C, queue downlink commands from the Queue tab.

For deployments using an external network server (e.g., The Things Stack), set the EC312-LoRaWAN gateway to Packet Forward mode instead of the built-in NS, then onboard the LT312 on that external NS the same way.

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