Y502-L LoRaWAN Serial DTU User Manual

• Y502-L Specification

Applicable model: Y502-L

Interfaces: 1 isolated RS485 + 1 isolated RS232

Direct I/O: None

Contents

1. Product Scope
2. Safety and Preparation
3. Hardware Installation
4. Serial Configuration
5. LoRaWAN Commissioning
6. Operating Modes
7. Data and Port Mapping
8. Gateway and Application Integration
9. Maintenance and Troubleshooting

1. Product Scope

Y502-L is an industrial LoRaWAN serial DTU. It connects PLCs, meters, data loggers, and serial sensors to a LoRaWAN network through RS485 or RS232.

The DTU supports transparent transmission, scheduled active acquisition, data-change reporting, remote serial commands, and approved remote configuration. Polling commands can contain Modbus RTU frames or custom protocol data, entered as ASCII text or hexadecimal bytes.

Y502-L has no DI, DO, AI, or AO channels. Use Y503-2220-L when the application needs direct digital or analog signal acquisition and control.

1.1 Data Path

Serial field device → Y502-L → LoRaWAN → Y501-L or Y511-L → Network Server or local service → Application

Match the radio plan and channel group across the DTU, gateway, and Network Server. Configure activation and class on the DTU and Network Server, and decode the application payload in the application service.

1.2 Main Limits

Item	Value
Supply voltage	DC 9-28 V
Recommended adapter	DC 12 V / 1 A
LoRaWAN version	1.0.3
Device classes	Class A / Class C
Transmit power	Up to 22 dBm
Serial ports	1 RS485 + 1 RS232
Mounting	35 mm DIN rail

2. Safety and Preparation

2.1 Safety Notes

• Read this manual before installation and commissioning.
• Connect the LoRa antenna before applying power.
• Use a regulated DC 9-28 V supply and observe the polarity.
• Remove power before changing the power, RS485, or RS232 wiring.
• Do not install the unit in direct sunlight, near heat sources, or in a flammable, explosive, wet, dusty, or smoky environment.
• Keep the antenna away from large metal surfaces, high-current cables, and other radio antennas.
• Keep the device away from strong electromagnetic fields and severe vibration.
• Prevent liquid from entering the enclosure.
• Connect the DTU to a field device only after confirming the voltage levels and serial wiring.

2.2 Prepare Before Installation

Prepare the following items:

• Y502-L DTU and the supplied mounting hardware
• LoRa antenna
• DC 12 V / 1 A adapter supplied with the standard package
• A USB-to-RS485 or USB-to-RS232 adapter for local configuration
• A computer and the approved PC configuration tool
• The RS485 or RS232 field device
• A Y501-L or Y511-L gateway with the same regional plan
• Network Server or local service credentials
• The device identity and LoRaWAN activation credentials
• The approved serial protocol and payload definition

Store AppKeys, session keys, passwords, and private server credentials in the approved secure system.

3. Hardware Installation

3.1 Mount the DTU

1. Check the enclosure, terminals, antenna, and power adapter for shipping damage.
2. Mount the DTU on a stable 35 mm DIN rail.
3. Leave enough space for the antenna connector, serial wiring, and power wiring.
4. Keep the unit ventilated and accessible for service.
5. Keep the antenna away from metal enclosures and high-interference equipment.

The nominal enclosure size is 87.65 × 36.54 × 59.3 mm.

3.2 Connect the Antenna and Power

1. Connect the LoRa antenna to the SMA antenna connector.
2. Confirm that the supply voltage is within DC 9-28 V.
3. Connect the power wires with the correct polarity.
4. Confirm that the adapter can supply the DTU and the connected field equipment.
5. Apply power only after checking the antenna and serial wiring.

The standard package includes a DC 12 V / 1 A adapter. The connected field device may require a separate power supply.

3.3 Connect RS485

1. Connect the field bus to the labeled A+ and B- terminals.
2. Match the baud rate, data bits, stop bits, and parity at both ends.
3. Confirm the field-device address and protocol.
4. Use shielded twisted-pair cable when required by the site environment.
5. Install termination and biasing only at the positions required by the bus design.

If the bus does not communicate, check the A/B polarity and the reference wiring before changing software parameters.

3.4 Connect RS232

Connect the three-wire RS232 interface according to the terminal labels:

Signal	Function
TXD	DTU transmit; connect to the field device RXD
RXD	DTU receive; connect to the field device TXD
GND	Connect to the field device signal ground

Match the serial parameters with the connected device. Confirm the DB9 pin assignment from the delivered wiring drawing before making a cable. RS232 requires RS232 voltage levels; do not connect it directly to TTL UART or RS485.

3.5 Buttons and Indicators

Control or indicator	Function
Factory reset button, short press	Reset the DTU
Factory reset button, double-click	Enter configuration mode
Factory reset button, hold for 5 s	Restore factory settings
POWER	On when power is normal
RUN	Blinks during normal operation
LoRa TX	Lights or blinks during LoRa transmission
RS232 RX	Blinks when RS232 data is received
RS485 RX	Blinks when RS485 data is received

Use factory reset only after saving the current configuration and confirming local access.

4. Serial Configuration

4.1 Connect the PC

Y502-L is configured through RS485 or RS232.

1. Power off the DTU and the field device.
2. Connect the PC to the required serial interface through a suitable USB converter.
3. Leave field equipment disconnected during initial configuration. Check the wiring, then power the DTU.
4. Open the supplied PC tool and allow it to scan the serial ports. Use manual connection if automatic discovery fails; double-click the reset button when the delivered procedure requires configuration mode.
5. Select the computer serial port and the communication parameters for the selected DTU interface.
6. Read and save the current configuration before making changes. Write the new settings, then read them back.
7. Exit configuration mode using the supplied procedure. Reconnect the field device with power off, then verify normal operation.

4.2 Factory Serial Parameters

Parameter	RS485	RS232
Baud rate	9600 bps	115200 bps
Data bits	8	8
Stop bits	1	1
Parity	None	None

The supported serial settings are:

Parameter	Available values
Baud rate	2400, 4800, 9600, 19200, 38400, 57600, 115200 bps
Data bits	8
Stop bits	1 or 2
Parity	None, odd, or even

Configure the DTU and the connected field device with matching values. For Modbus RTU, also match the slave address, function code, register map, byte order, and scaling.

The specification lists the baud rates above. Newer configuration tools may offer additional rates; use them only after confirming support on the delivered firmware and testing both interfaces.

4.3 Serial Acquisition Delay

When the baud rate is low or several acquisition scripts run in sequence, increase the serial acquisition delay as required by the field device. A delay that is too short may cause incomplete responses or acquisition failures.

5. LoRaWAN Commissioning

5.1 Select the Regional Plan

Select the plan that matches the ordered DTU, gateway, Network Server, and local radio regulations:

Plan	Availability
CN470	Reference deployment plan
EU433	Supported regional variant
EU868	Supported regional variant
AU915	Supported regional variant
IN865	Supported regional variant
AS923	Supported regional variant
RU864	Supported regional variant
US915	Supported regional variant

The gateway, Y502-L, and Network Server must use compatible regional plans and channel groups. Confirm the exact DTU variant before delivery.

5.2 Configure Activation

OTAA is recommended for new deployments.

For OTAA, prepare:

• DevEUI
• JoinEUI or AppEUI, according to the Network Server
• AppKey

For ABP, prepare:

• DevAddr
• Network session key
• Application session key

Enter the values in the Network Server and the DTU configuration tool according to the selected activation method. Store the credentials in the approved secure system.

5.3 Select the Device Class

• Class A: The DTU opens receive windows after an uplink. Use this mode for normal low-duty-cycle applications.
• Class C: The powered DTU listens for downlinks almost continuously, except while transmitting and during the Class A receive-window sequence. Use this mode when the application needs more responsive downlinks and the power budget permits it.

Set the same device class on the DTU and its Network Server profile. The gateway forwards the scheduled downlinks.

5.4 Configure Radio Parameters

Configure the following parameters when required by the Network Server:

• Start and end channel
• Spreading factor, SF7 to SF12
• Transmit power
• ADR
• Confirmed or unconfirmed uplink
• RX1 and RX2 parameters
• Uplink and downlink timing

Use ADR for stationary devices when the Network Server supports it and the radio environment is stable. Match the RX2 frequency and spreading factor to the Network Server.

5.5 Register the DTU

1. Configure the selected regional plan on the Y501-L or Y511-L gateway.
2. Register the gateway in the Network Server, or enable the local service when the ordered gateway configuration includes it.
3. Register Y502-L with the selected activation method.
4. Apply the device class, channel, and application settings.
5. Reset or power-cycle the DTU when the configuration tool requests it.
6. Check the first join and uplink in the Network Server and gateway logs.

Commission one DTU first. Add other devices after the complete uplink and downlink path works.

6. Operating Modes

6.1 Transparent Transmission Mode

Transparent mode is the factory operating mode. The DTU can obtain field data in two ways:

1. The field device actively sends data, and the DTU forwards the received serial data through LoRaWAN.
2. The application sends a downlink command, and the DTU sends that command to the field device and returns the response.

Use transparent mode when the application handles the serial protocol. The link carries packets with LoRaWAN payload and timing limits, so it does not preserve continuous serial timing. Set request timeouts to cover the complete wireless path and verify the longest expected message.

6.2 Active Acquisition Mode

Active acquisition lets the DTU send configured read commands at scheduled intervals. This reduces the need for frequent gateway downlinks.

Configure each task with:

• Serial interface
• Command format: HEX or ASCII
• Command content
• Acquisition interval
• Uplink port
• Enable or disable state

The DTU supports up to 16 acquisition scripts. The script interval is 10-86,400 seconds. Each script can contain up to 40 bytes.

The configuration tool can generate Modbus read commands from the device address, function code, starting register, and register count. Verify the command against the field-device manual. With the sensor connected, use the script-test function and check its response before enabling periodic acquisition.

6.3 Heartbeat and Data-Change Reporting

The heartbeat task (script 0) reports device information at the configured interval. Its payload content is fixed in the documented firmware; configure the interval rather than treating it as another user acquisition script.

Data-change reporting compares adjacent acquisition results and reports when the configured data changes. Use an appropriate acquisition interval and change rule for the field device to avoid unnecessary uplinks.

6.4 Remote Configuration

Y502-L supports approved remote parameter and command configuration through LoRaWAN downlinks. Use remote configuration only when uplink and downlink communication is stable.

The documented configuration protocol returns a response on FPort 43 and restarts about one minute after a successful change. Confirm this behavior on the delivered firmware. Verify the new settings and the first successful uplink after restart.

Keep frame-counter validation enabled on the Network Server. Before resets or firmware changes, confirm how the DTU retains counters and sessions. Fast-send modes can reduce downlink reception; test the full command/response path before enabling them.

7. Data and Port Mapping

LoRaWAN carries bytes. HEX is a display or entry format; a server API may represent those bytes as Base64 instead. Confirm the encoding before decoding or sending data. The port map below applies to the documented firmware baseline; read back the actual configuration because script ports can be changed.

7.1 Standard Uplink Ports

Port	Function
1-16	Acquisition script 1 to script 16
40	Heartbeat packet
51	RS232 transparent uplink
52	RS485 transparent uplink
214	Restart packet
215	Power-on packet

7.2 Response Ports

Port	Function
42	Command response
43	Downlink configuration response

The payload parser must use the definition delivered for the ordered firmware. Do not derive byte positions, scaling, or port behavior from a different firmware version.

7.3 Commissioning Record

Record the following values for each deployed DTU:

• Model and hardware variant
• Device identifier and DevEUI
• Regional plan and channel group
• Activation method and device class
• RS485 or RS232 selection
• Serial parameters
• Field-device address and protocol
• Script commands and intervals
• Uplink ports and payload version
• Gateway identifier and Network Server application

Keep credentials and keys in the approved secure system rather than in the commissioning record or public documents.

8. Gateway and Application Integration

8.1 Gateway Checks

Before production commissioning:

• Confirm that Y501-L or Y511-L is online.
• Confirm that the gateway and Y502-L use the same regional plan and channel group.
• Confirm that the Network Server receives gateway traffic.
• Confirm that the gateway antenna is connected.
• Confirm that the Network Server application uses the correct payload decoder.

8.2 Uplink Verification

Check the following items in the application:

• Device identity
• Uplink timestamp
• Serial interface and port
• Heartbeat or device status
• Acquisition command and response
• Parsed field values
• Communication error status

Compare one received value with the field-device display or a reference tool before enabling long-term polling.

8.3 Downlink Verification

1. Confirm stable uplinks.
2. Send one approved serial or control command.
3. Confirm the command response.
4. Check the field-device state or returned value.
5. Record the result in the commissioning record.

For Class A, queue the downlink on the Network Server before the next uplink; the server schedules it in a receive window. Class C provides more downlink opportunities but does not guarantee response time. Confirm execution from the serial response or equipment state.

9. Maintenance and Troubleshooting

9.1 Maintenance

• Keep the antenna connected during normal operation.
• Inspect the power adapter, antenna connector, DIN-rail mounting, and serial terminals during scheduled maintenance.
• Back up the configuration before changing serial or LoRaWAN parameters.
• Record firmware, regional plan, class, serial settings, and payload version with the device identifier.
• Test one transparent transmission and one active acquisition after a firmware or configuration change.
• Keep stable power during configuration updates.
• Restore factory settings only after saving the current configuration.

9.2 Troubleshooting

Symptom	Checks and corrective action
DTU does not start	Check supply voltage, polarity, adapter current, terminals, and visible damage.
No LoRaWAN join	Check the regional plan, antenna, gateway status, DevEUI, activation credentials, device class, and Network Server record.
Uplink does not arrive	Check gateway-to-server connectivity, channel group, antenna, frame counters, payload routing, and application configuration.
RS485 data is missing	Check A/B polarity, baud rate, data format, device address, protocol, termination, and polling command.
RS232 data is missing	Check TXD/RXD/GND wiring, baud rate, data format, and field-device protocol.
Script acquisition fails	Check the command format, response timeout, serial acquisition delay, field-device address, and script interval.
Data values are incorrect	Check byte order, register type, scaling, signedness, unit conversion, and payload decoding.
Downlink is delayed	Check Class A receive-window timing, confirmed-uplink settings, RX2 parameters, and gateway downlink capacity.
Communication drops repeatedly	Check antenna placement, interference, supply stability, gateway logs, and regional radio settings.

If the issue remains, record the model, regional plan, device identifier, gateway identifier, firmware version, time of failure, signal values, and a redacted log. Exclude passwords, AppKeys, session keys, and private server credentials.

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YenGear
Hunan YenGear Tech Co., Ltd.
Room 21014, Building 1, Fudi Xingguang Tiandi, Yingxin Road, Yuhua District, Changsha, Hunan, China
[email protected] · www.yengear.com