LT312 User Manual¶

LoRaWAN DTU Series
User Manual

Version1.0 | www.inhand.com.cn

The software described in this manual is provided under a license agreement and may only be used in accordance with the terms of that agreement.

Copyright Notice¶

Trademarks¶

The InHand logo is a registered trademark of InHand Networks.

All other trademarks or registered trademarks mentioned in this manual belong to their respective manufacturers.

Disclaimer¶

The company reserves the right to make changes to this manual without prior notice when the product is subsequently modified. The company shall not be liable for any direct, indirect, intentional or unintentional damage or hazards caused by improper installation or use.

1 Introduction¶

This user manual will guide you on how to use this product. Please read this user guide carefully before using the product.

All contents of this document are legally protected. Without permission, no organization or individual may reproduce or distribute this document in any way.

We make every effort to ensure the accuracy of this document, but unavoidable errors may still exist. We will periodically review the contents of this document to keep it consistent with the corresponding product. We would greatly appreciate your suggestions.

The following describes the correct usage of the product to prevent danger and property damage. Please read this manual carefully before using the device and strictly follow it during use.

2 Safety Instructions¶

Avoid placing the device in direct sunlight, near heat sources, or in flammable, explosive, humid, dusty, or sooty environments
Keep away from fire, strong electric fields, strong magnetic fields, and complex interference sources to avoid permanent damage
Avoid large metal equipment during installation; the antenna must not be placed inside a metal enclosure
Do not install on high-vibration equipment; avoid external impact or vibration.
Do not allow liquid to drip or splash into the device; outdoor installation requires proper waterproofing.
Wiring must be performed with the device powered off, and strictly follow the manual.
This product emits radio frequency signals, which may interfere with other wireless communications; this cannot be completely avoided in certain environments.
Strictly follow the requirements of this manual during use. The company is not responsible for damage caused by improper operation.
Do not modify this product; avoid using it in environments beyond the specified temperature and humidity range
When removing the housing, be careful not to lose or damage internal components.

3 User Guide¶

3.1 Configuring the LT312¶

Preparation:

LT312 device;
RS485 or RS232 device (referred to as the “application device”);
USB-to-RS485 / USB-to-RS232 cable;
PC;
Inhand-Toolbox configuration tool software;

Configuration steps:

Set the LT312 serial port parameters so they match those of the application device;
Set the LT312 to transparent transmission or timed acquisition reporting;
Set the LT312 communication frequency to match the LoRaWAN gateway;
Fill in the network access parameters on the LoRaWAN server / LoRaWAN edge gateway (a gateway with a LoRaWAN server) to register the LT312 device.

3.1.1 Obtaining Device Information¶

Connect the LT312 to the PC via USB-to-RS485 or USB-to-RS232, then open the Toolbox tool;
Set the serial port parameters, click Open Serial Port, click “Read Data” to obtain all LT312 parameters;

Default Serial Port Parameters¶

Serial Port Parameter	RS485	RS232
Baud Rate	9600	115200
Data Bits	8	8
Stop Bits	1	1
Parity	None	None

3.1.2 Serial Port Parameter Settings¶

In this step, configure the LT312 serial port parameters to match those of the application device so that the LT312 and the application device can establish serial communication.

Serial Port Acquisition Delay:

At low baud rates with multiple script acquisition, the serial acquisition delay should be extended appropriately; otherwise acquisition failures may occur. Applicable when the baud rate is below 1200.

Baud Rate Settings:

110/300/600/1200/2400/4800/9600/14400/19200/38400/43000/57600/76800/115200

RS485 Debug Information:

Once enabled, more detailed serial data on the 485 interface can be printed for easier testing and debugging.

4) RS232 Debug Information:

Once enabled, more detailed serial data on the 232 interface can be printed for easier testing and debugging.

Note: Some sensors may fail acquisition because of the DTU debug print information. Therefore, it is recommended to disable serial debug information during script acquisition

3.1.3 Working Mode Settings¶

Transparent transmission mode:

The LT312 is shipped with transparent transmission mode enabled by default. In transparent mode, the LT312 obtains data from the application device in two ways:

The application device actively reports data; the LT312 uploads the received data to the gateway;
The gateway sends a command to the LT312 to obtain data from the application device.

Active acquisition mode:

Since most LoRaWAN gateways have few downlink channels, the LT312 features script-based acquisition. This function uses configuration commands sent by the LT312 at a configured interval to obtain data from the application device, thereby reducing the downlink load on the gateway.

Note: A script is a command sent to the application device to read data. When writing a script, refer to the application device's communication protocol.

Script 0 is the heartbeat packet, used to periodically report device information to determine whether the device is online; the interval is configurable. (For detailed parsing, refer to Section 3.3 of the communication protocol.) (The contents of this heartbeat packet cannot be modified)
Scripts support both HEX and ASCII formats, with a maximum length of 40 bytes.

Up to 16 scripts are supported for acquisition. With multiple scripts, allocate the acquisition intervals reasonably.
The minimum acquisition interval is 10 s and the maximum is 86400 s.

Note: Set the minimum acquisition interval according to the sensor device status; setting it too short may cause acquisition failure.

After configuring a script, you can verify its correctness. Fill in the script, check the script enable option, and click Script Test.

Note: Script testing requires the corresponding sensor device to be connected to the corresponding serial port. Also make sure the wiring is correct.

The steps above complete the communication configuration between the LT312 and the application device. Next, configure communication between the LT312 and the LoRaWAN network

3.1.4 Basic LoRaWAN Configuration¶

Before connecting the device to the LoRaWAN network, the relevant network communication parameters must be set,

and complete the LoRaWAN network configuration as follows

If you are unfamiliar with common LoRaWAN parameters, refer to the following table for their meanings:

Parameter	Description
DevAddr	Device short address: used for ABP network access; can be found on the product label.
DevEUI	Unique device identifier: used for OTAA network access; can be found on the product label.
AppEUI	Application identifier: a 64-bit globally unique identifier used to identify and manage a specific application in the LoRaWAN network. Default: 0000000000000001
AppSKey	Application session key: used in ABP mode; the key used to encrypt and decrypt data transmitted between the device and the application server. Default key: 2b7e151628aed2a6abf7158809cf4f3c
NwkSKey	Network session key: used in ABP mode; the key used to encrypt and decrypt data transmitted between the device and the network server, and used for device authentication. Default key: 2b7e151628aed2a6abf7158809cf4f3c
AppKey	Application key: used in OTAA mode; the key used to encrypt and decrypt data transmitted between the device and the application server, and used for device authentication. Default key: 2b7e151628aed2a6abf7158809cf4f3c
ABP Mode	Local activation: a method for LoRaWAN devices to join the network. The device's network session key, application session key, and short address are pre-configured at the factory, allowing plug-and-play communication. Suitable for application scenarios that do not require frequent key changes.
OTAA Mode	Over-the-air activation: a method for LoRaWAN devices to join the network. Device activation is performed through dynamic key negotiation and over-the-air transmission, providing higher security and flexibility. Suitable for mobile and cross-network application scenarios .
Class A	Class A device: uses the standard ALOHA communication mode, including uplink, downlink, and fixed receive windows. Suitable for most low-power sensors and application scenarios.
Class C	Class C device: keeps receive window 2 open at all times to ensure downlink messages can be received at any time. Suitable for application scenarios requiring low latency and high-frequency downlink communication.
ADR	Adaptive data rate: when enabled, the network server can adjust the terminal's data rate and power consumption. Recommended when the device is stationary.
ACK	Acknowledgement: a message confirming successful packet reception, ensuring reliable data transmission. Suitable for application scenarios requiring high reliability.
Initial Channel	The first frequency channel used when the device joins the LoRaWAN network or communicates for the first time.
End Channel	The last frequency channel used by the device within the configured frequency range, ensuring communication within the specified spectrum range .
Power	Transmit power: 27 dBm by default for the PA version, 22 dBm by default for the standard version
SF	Spreading factor: when ADR is disabled, the device transmits data using the configured SF. The smaller the SF, the higher the transmission rate, which suits short-distance transmission, and vice versa. Setting range: 7-12
Number of Re-activations	In OTAA mode, the number of times the device retries network access after a failure.

3.2 Extended Parameters¶

Function	Description
Sleep Mode	After transmitting data, the DTU automatically enters low-power mode. Suitable for battery-powered applications. Note: The LT312 is not a low-power DTU. Do not enable this feature.
Fast Transmission Mode	Sacrifices downlink reception performance for the fastest acquisition and upload. In special cases, transparent mode can send 1 data packet per second at the fastest. Note: In fast transmission mode, downlink data may not be received.
OTAA Hot Reload	After successful network access in OTAA mode, a power-off restart does not require re-registering; the device can communicate directly.
Simple Counter	Uplink counter up to 65535; disabled by default. Note: To use this feature, coordination with the LoRaWAN server is required.
Continuous Reception	When enabled, power consumption increases but reception stability improves.
Channel Activity Detection	Quickly determines whether there is ongoing LoRa signal transmission on the current LoRa channel. If the channel is detected idle, data is sent immediately; if the channel is detected busy, it waits a while and retries.
Uplink Counter Persistence	The terminal's uplink counter is not cleared on power loss; restoring factory settings clears the counter.
Window 1 Open Time	Default 1 s. Changing is not recommended; contact technical personnel if issues arise.
Window 1 Duration	Default 3 s. Changing is not recommended; contact technical personnel if issues arise.
Window 2 Open Time	Default 2 s. Changing is not recommended; contact technical personnel if issues arise.
Window 2 Duration	Default 3 s. Changing is not recommended; contact technical personnel if issues arise.
Window 2 SF	The spreading factor of receive window 2. Default SF12, settable from SF7 to SF12. When the DTU is modified, change the server's window 2 spreading factor accordingly. Used for frequent downlink data packets to multiple Class C devices. Note: Modifying requires coordination with the LoRaWAN server.
Window 2 Downlink Channel	Default channel 25 (505.3). Used for frequent downlink data packets to multiple Class C devices. Note: Modifying requires coordination with the LoRaWAN server.
Multicast Switch	When enabled, DTUs can be configured in batches.
Multicast Channel	Default channel 25 (505.3 MHz), window 2 downlink frequency
Multicast Window 2 SF	Default SF12 (DR0), window 2 downlink spreading factor
Multicast Address	Default: ffffffff, multicast short address
Multicast AppSKey	Multicast application key Default: 2b7e151628aed2a6abf7158809cf4f3c
Multicast NwkSKey	Multicast network key: Default: 2b7e151628aed2a6abf7158809cf4f3c

3.3 Communication Protocol¶

Both uplink and downlink data of the device are based on hexadecimal format.

1. Restart packet

Restart packet port: 214

Data packet:

01 indicates hardware restart

03 indicates software restart

04 indicates hardware watchdog restart

05 indicates software watchdog restart

2. Uplink data packet

Heartbeat packet parsing

Heartbeat packet port: 40

Heartbeat packet: cede3400003c0a8201460000000100000000c6eced

cede	Header
34	Packet type; 34 indicates a heartbeat packet
00003c	Heartbeat packet period, unit s, decimal: 60 s
0a82	Module temperature, unit °C, decimal / 100: 26.9 °C
0146	Module voltage, unit V, decimal / 100: 3.26 V
00000001	Script 1 enabled 4 bytes, 32-bit data; each bit represents the on/off state of one script; 0 = off, 1 = on
00000000	Number of scripts currently collected successfully Example: if 3 scripts are all collected successfully, it displays 00000003
C6	XOR checksum
eced	Packet tail

Power-on Packet Parsing¶

Power-on packet port: 215

Power-on packet: 110401020000000104

11	Device type: power-enhanced DTU 10: standard version DTU
04	Communication protocol: 04
0102	Software version: 1.2
00000001	Indicates script 1 is enabled 4 bytes, 32-bit data; each bit represents the on/off state of one script; 0 = off, 1 = on
04	Device battery level 04: full

Packet Port Description¶

Port No.	Description
214	Restart packet
215	DTU power-on packet
40	Heartbeat packet
42	Data packet returned for a get-command
43	Reply packet for downlink configuration data
51	RS232 transparent uplink data packet
52	RS485 transparent uplink data packet
1	Script 1 data packet
2	Script 2 data packet
3	Script 3 data packet
…	…
15	Script 15 data packet
16	Script 16 data packet