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 forwards serial data, polls equipment at scheduled intervals, and reports data changes. It accepts Modbus RTU or custom polling commands in ASCII or HEX format. Remote commands and configuration use the installed firmware's downlink protocol.

For direct digital or analog signal wiring, use the Y503-2220-L RTU.

1.1 Data Path

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

Match the DTU, gateway, and Network Server radio plan and channel group. Set activation and device class on the DTU and its server profile; decode payloads in the application.

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

• 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.
• Check voltage levels and serial wiring before attaching the field device.

2.2 Prepare Before Installation

• 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 PC configuration tool supplied for the firmware
• The RS485 or RS232 field device
• A Y501-L or Y511-L gateway with the same regional plan
• Network Server or local-service access details
• Device identity and LoRaWAN activation credentials
• Field-device protocol and firmware payload definition

3. Hardware Installation

3.1 Mount the DTU

1. Inspect 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. Measure the supply voltage; it must be within DC 9–28 V.
3. Connect the power wires with the correct polarity.
4. Check the adapter rating against the DTU and field-equipment load.
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. Set 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 serial settings with the field device. Check the supplied wiring drawing for DB9 pin assignments before making a cable. Use an appropriate converter for TTL UART or RS485 equipment; this port uses RS232 voltage levels.

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

Back up settings and arrange local access before a factory reset.

4. Serial Configuration

4.1 Connect the PC

Use RS485 or RS232 for local configuration.

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 scan the serial ports. If discovery fails, select the port manually. Double-click the reset button if the supplied procedure requires configuration mode.
5. Select the computer serial port and the communication parameters for the selected DTU interface.
6. Back up the current configuration. 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

Match these settings with the field device. For Modbus RTU, also check the slave address, function code, register map, byte order, and scaling.

If the configuration tool offers additional baud rates, check firmware support and test both interfaces before using them.

4.3 Serial Acquisition Delay

Increase the serial acquisition delay for low baud rates or sequential polling tasks when the equipment needs more time to respond. A short delay can truncate responses or cause acquisition failures.

5. LoRaWAN Commissioning

5.1 Select the Regional Plan

Select a plan supported by the DTU hardware and permitted in the installation region:

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

Match the selected plan and channel group with the gateway and Network Server.

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 credentials in the DTU tool and Network Server device record. Store keys and passwords in the project credential store.

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

Set radio parameters to match 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. For OTAA, look for a successful join and uplink in the logs. For ABP, check that the server accepts an uplink with the provisioned session.

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

6. Operating Modes

6.1 Transparent Transmission Mode

Transparent transmission is the factory operating mode:

1. When the field device sends data, the DTU forwards the serial bytes through LoRaWAN.
2. When the application sends a downlink command, the DTU passes it to the field device and returns the response.

Use this mode when the application handles the serial protocol. LoRaWAN packet size and scheduling limit throughput and change serial timing. Set request timeouts for the complete wireless path and test the longest expected message.

6.2 Active Acquisition Mode

In active acquisition mode, the DTU sends scheduled read commands locally, reducing the need for downlink polling.

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 is fixed in the documented firmware. Set its interval separately from the user acquisition scripts.

Data-change reporting compares consecutive acquisition results. Set the acquisition interval and change rule to capture relevant changes without unnecessary uplinks.

6.4 Remote Configuration

Remote parameter and command configuration uses LoRaWAN downlinks. Establish stable uplinks and downlinks before changing settings remotely.

The documented protocol responds on FPort 43 and restarts the DTU about one minute after a successful change. Check this behavior on the installed firmware, then read back the settings and verify uplinks after restart.

Keep server frame-counter validation enabled. Check counter and session retention before a reset or firmware change. Fast-send modes can reduce downlink reception; test command/response operation before enabling them.

7. Data and Port Mapping

LoRaWAN carries bytes. HEX is a display or entry format; server APIs may use Base64. Check the encoding before sending or decoding payloads. These default FPorts apply to the documented firmware; read back the configuration for any changed script ports.

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

Build the parser from the installed firmware's payload definition, including byte positions, scaling, and FPort behavior.

7.3 Commissioning Record

Record each DTU's deployment settings:

• 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

Reference the credential store separately; omit keys and passwords from the commissioning record.

8. Gateway and Application Integration

8.1 Gateway Checks

Check the gateway-to-application path:

• Bring Y501-L or Y511-L online in the Network Server.
• Match its frequency plan and channel group with the DTU.
• Look for gateway traffic in the server.
• Inspect the gateway antenna connection.
• Test the application decoder with a known payload.

8.2 Uplink Verification

Inspect the application records for:

• 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. Verify stable uplinks.
2. Send one supported serial or control command to a test device.
3. Read the command response and check the field-device state or returned value.
4. Record the result.

For Class A, queue the command before the next uplink so the server can use a receive window. Class C offers more receive opportunities; server scheduling and radio capacity still affect command timing. A radio acknowledgement alone does not prove execution.

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.

For support, provide the model, frequency plan, device and gateway identifiers, firmware version, failure time, RSSI/SNR, and redacted logs. Remove 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