Y202-W Standard WiFi DTU Technical Manual

Introduction
System Overview
Hardware Interfaces
Electrical Specifications
Serial Configuration & Packaging
WiFi & Ethernet Networking
Socket Protocol Workflows
Modbus Gateway & JSON Services
Advanced Functions
Remote Management & Diagnostics
AT Command Highlights

1. Introduction

Y202-W is the WiFi-enabled member of the Yanji standard DTU family. It converts two independent RS232/RS485 channels to WiFi or 10/100 M Ethernet with dual sockets per port, Modbus RTU ↔ TCP gateway, JSON uploader, HTTP/MQTT clients, registration packets, heartbeats, OTA, and remote AT workflows inherited from the MiniLink Y201/Y202 series. The compact 84 × 70 × 25 mm enclosure uses a DB9 plus pluggable terminal and supports 5–36 V DC, making it ideal for retrofitting panels where only wireless uplinks are available.

Item	Description
MCU & OS	Dual-core 240 MHz MCU + RTOS, dual watchdog
Serial Interfaces	2 × RS232/RS485 (COM1 DB9, COM2 3-pin terminal)
Wireless	802.11 b/g/n @ 2.4 GHz, AP / STA / AP+STA
Ethernet	10/100Base‑T RJ45, static/DHCP
Services	Transparent sockets, HTTP client, MQTT client, Modbus gateway, JSON uploader, OTA
Power	5–36 V DC via terminal or DC barrel (Ø5.0 mm)

Dimensional drawings, SKU matrix, and ordering information reside in the Y202-W Specification.

2. System Overview

Dual Serial Engine – COM1 and COM2 are isolated from each other, each exposing Socket A/B plus packaging and heartbeat parameters.
Flexible Uplink – WiFi can run AP, STA, or AP+STA concurrently, while an RJ45 port provides wired fallback; AT+NETIF selects the active interface.
Firmware Parity – Shares the same feature set as Y202-R (TCP/UDP, HTTP, MQTT, Modbus gateway, JSON uploader, EDP peer-to-peer, remote AT, OTA, watchdog).
Built-In UI – Web console (192.168.4.1 in AP mode) mirrors AT commands and provides Status/System/Port tabs.
Industrial Protections – 5–36 V input, reverse polarity guard, EFT/ESD hardening, dual watchdog, programmable reboot-on-silence, and offline cache.

3. Hardware Interfaces

Group	Description
Power	5.08 mm 2-pin terminal (V+/V-) and Ø5.0 mm DC barrel (center positive).
Serial	COM1 DB9 male (factory RS232, switchable to RS485); COM2 3-pin terminal (A/B/GND or TX/RX/GND).
WiFi	SMA female connector for external 2.4 GHz antenna.
Ethernet	RJ45 10/100Base‑T with LINK/ACT LEDs, auto MDI/MDIX.
USB	Micro-USB (CDC) for local AT commands and firmware download.
Button	Reload – hold ≥3 s to revert to default parameters (equivalent to `AT+RSTCFG`).

LED Behavior

LED	Behavior	Meaning
POWER	Steady on	DC supply OK
WORK (WiFi)	Slow blink (~1 s)	WiFi connected (STA) or AP broadcasting
WORK (WiFi)	Fast blink (~300 ms)	WiFi disconnected / searching
LINK	On	Ethernet link established
ACT	Blink	Ethernet activity
TX1/RX1	Blink	COM1 traffic
TX2/RX2	Blink	COM2 traffic

4. Electrical Specifications

Parameter	Value
Supply Voltage	5–36 V DC
Typical Current	55 mA @ 12 V (WiFi idle)
Operating Temp	-40 °C ~ +85 °C
Humidity	5% ~ 95% RH, non-condensing
Power Protection	Reverse polarity, surge clamp, user-fused recommended
Watchdog	Hardware + software; programmable reboot timer (`AT+SOCKRTO`)

Ensure shielding for RS485 pairs and provide ≥15 mm clearance for antenna rotation and airflow. Keep WiFi antennas outside metal cabinets or use an extension pigtail.

5. Serial Configuration & Packaging

5.1 UART Parameters

Per-port command: AT+UARTn=<baud>,<databits>,<stopbits>,<parity>,<fc> (n = 1/2).

Field	Options	Default
Baud Rate	2,400–460,800 bps	115,200
Data Bits	7 / 8	8
Stop Bits	1 / 2	1
Parity	NONE / EVEN / ODD	NONE
Flow Control	NFC (RS232) / auto-direction (RS485)	NFC

5.2 Packaging (AT+UARTTLn)

Length trigger: 64–1024 bytes (default 1024).
Gap trigger: 0–300 ms (0 = auto based on baud, default 0).
Flush occurs when either threshold is met. Example: AT+UARTTL1=30,512.

5.3 Modes

Transparent Mode – Default serial tunnel.
AT Command Mode – Send +++, wait ≥500 ms, send a, then issue commands; exit with AT+EXIT.
Broadcast AT / Remote AT – Enable via AT+EXAT for socket-side management; protected by keyword.

6. WiFi & Ethernet Networking

6.1 WiFi AP Mode (Default)

Parameter	Value
SSID	`HY-W502`
Security	WPA2-PSK
Password	`admin123` (example, change immediately)
IP	`192.168.4.1`
DHCP	Enabled (1–6 STA)
HTTP Login	`admin` / `admin`

Steps:

Power on and connect a PC/phone to SSID HY-W502.
Browse to http://192.168.4.1, enter credentials.
Configure WiFi STA, Ethernet, serial, sockets, Modbus, heartbeats.
Save and reboot.

6.2 WiFi STA / AP+STA

AT+NETIF=STA to join an external AP; set credentials via AT+STA=<ssid>,<password>.
AT+NETIF=APSTA keeps the device discoverable while connected upstream (AP radio follows STA channel).
Channel selection for AP mode: AT+WCH=<1-13>.
STA status query: AT+STALK.

6.3 Ethernet Mode

AT+NETIF=ETH enables RJ45 and disables WiFi radio.
Static IP: AT+WAN=STATIC,192.168.10.8,192.168.10.1,255.255.255.0.
DHCP: AT+WAN=DHCP.
DNS backup: AT+DNS=114.114.114.114.
LAN discovery broadcasts UDP on port 8168 with keyword HuayunIOT (AT+SEARCH=<port>,<key>).

7. Socket Protocol Workflows

Each COM port exposes Socket A and Socket B. Enable with AT+SOCKENns=ON and configure type/address/port via AT+SOCKns=....

7.1 TCP Client / Server

TCP Client example (COM1 SocketA):

AT+SOCKEN1A=ON
AT+SOCK1A=TCPC,10.10.10.50,9000
AT+REBOOT

Auto-reconnect occurs every second.

TCP Server example (COM2 SocketB):

AT+SOCKEN2B=ON
AT+SOCK2B=TCPS,0.0.0.0,8010
AT+REBOOT

Up to eight TCP clients per socket; data is broadcast to all connected clients.

7.2 UDP Client / Server

UDPC requires target IP/port; optional localport ensures firewall pinholes.
UDPS listens on a local port and replies to the most recent sender—ideal for mobile maintenance tools.

7.3 HTTP Client

Switch socket to HTPC.
Configure headers (AT+HTPHDn=Connection:keep-alive|Content-Type:application/json).
Select request type (AT+HTPREQn=GET/POST/AUTO).
For POST, set URL via AT+HTPURLn=/api/v1/upload.
In AUTO mode, include the full URI in the payload (e.g., http://example.com/path\r\nPAYLOAD).

7.4 MQTT Client

AT+MQCONFn=<n>,<type>,<addr>,<port> defines broker endpoint; type can be TCP or TLS (via external gateway).
AT+MQAUTHn=<user>,<password> sets credentials.
AT+MQPUBn=<topic>,<qos> and AT+MQSUBn=<topic>,<qos> control data flow.
Aliyun/Baidu/OneNET helpers: AT+MQALI, AT+MQBAI, AT+MQONE.

7.5 Registration Packets & Heartbeats

Registration type: AT+REGTPn=MAC/CUS.
Mode: AT+REGMDn=OFF/FIRST/EVERY/ALL.
Payload: AT+REGDATn=<hex>.
Heartbeat mode: AT+HEARTMDn=OFF/NET/UART, interval via AT+HEARTTMn (1–86,400 s), payload via AT+HEARTDATn.

7.6 Peer-to-Peer (EDP)

Acquire EDP IDs from Yanji, configure via AT+SOCK1A=EDP,huayuniot,888 and AT+EDP1=<target_id>,OFF.
Supports one-to-one, one-to-many, many-to-one tunnels while still allowing HTTP/MQTT on other sockets.

8. Modbus Gateway & JSON Services

Enable per port: AT+MBMDn=ON. Modbus TCP frames on sockets convert to RTU on the associated COM, preserving timing.
Scheduler: AT+MBCFGn=<enable>,<interval_ms>,<period_s> defines poll timing; AT+MBCMDn=<hex> holds RTU frames.
JSON uploader:
```
AT+HJREG=loop_voltage,0,1000,0.1,V
AT+MBJSn=ON,30
```
Data can be delivered via HTTP (HTPC sockets) or MQTT topics.

9. Advanced Functions

Feature	Command	Description
Offline Cache	`AT+CACHEn=ON/OFF`	Buffers up to 50 frames when uplink fails; auto-flush on recovery.
No-Data Reboot	`AT+SOCKRTO=<minutes>`	Reboots device if no data arrives within the window (default 1,440 min).
Remote AT	`AT+EXAT=<mode>,<keyword>`	Enables password-protected AT control via sockets after LAN discovery.
HTTP OTA	`AT+DOWNLOAD=<uri>`	Pulls firmware from HTTP server, verifies, then swaps after reboot.
Parameter Backup	`AT+BKCFG`, `AT+RSTCFG`, `AT+CLRCFG`	Backup, restore, or factory reset configuration partitions.
WiFi Scan	`AT+SCAN`	Lists surrounding AP SSID/RSSI/auth for site surveys.
STA List	`AT+APLK`	Shows clients connected to the AP radio.

10. Remote Management & Diagnostics

After commissioning, run AT+BKCFG and store the backup file in your CMDB for rapid field recovery.
Enable registration packets (FIRST) so head-ends receive MAC/SN whenever sockets connect.
Configure NET heartbeats (e.g., 60 s) to detect uplink issues; optionally enable UART heartbeats for PLC keepalive.
Set AT+SOCKRTO=30 (minutes) when unattended installations must auto-recover from silent networks.
Schedule OTA windows and keep firmware hosted on accessible HTTP servers; use AT+DOWNLOAD for remote upgrades.
Use LAN discovery (AT+SEARCH=8168,HuayunIOT) plus remote AT to audit fleets without local access.
For WiFi STA deployments, monitor AT+STALK RSSI values (> -65 dBm recommended).

Diagnostic commands:

AT+DEVINFO – Model, firmware, MAC, SN, build time.
AT+SOCKLK – Socket connection states.
AT+PING=<host> – Reachability tests (returns latency or error).
AT+NETSTAT – Interface statistics (WiFi/Ethernet).
AT+LOG=<level> – Sets temporary debug verbosity.
Reload button – Restores last saved configuration without host.

11. AT Command Highlights

Command	Purpose
`AT+LIST`	Enumerate supported commands
`AT+VER`	Firmware version
`AT+NETIF`	Select AP / STA / AP+STA / Ethernet
`AT+AP`, `AT+STA`, `AT+WCH`, `AT+NUMSTA`	WiFi SSID/password/channel/STA limit
`AT+WAN`, `AT+DNS`, `AT+SEARCH`	Ethernet IP/DNS/discovery
`AT+UARTn`, `AT+UARTTLn`	Serial parameters and packaging
`AT+SOCKns`, `AT+SOCKENns`	Socket definition and enablement
`AT+REGTPn`, `AT+REGMDn`, `AT+REGDATn`	Registration packets
`AT+HEARTMDn`, `AT+HEARTTMn`, `AT+HEARTDATn`	Heartbeat settings
`AT+MBCFGn`, `AT+MBCMDn`, `AT+MBJSn`, `AT+HJREG`	Modbus scheduler & JSON mapping
`AT+MQCONFn`, `AT+MQAUTHn`, `AT+MQPUBn`, `AT+MQSUBn`	MQTT workflows
`AT+HTPURLn`, `AT+HTPHDn`, `AT+HTPREQn`	HTTP client settings
`AT+EDPn`	Peer-to-peer configuration
`AT+DOWNLOAD`	HTTP OTA
`AT+CACHEn`, `AT+SOCKRTO`	Offline cache & auto-reboot
`AT+BKCFG`, `AT+RSTCFG`, `AT+CLRCFG`	Backup/restore/factory reset

Linked Documents: Y202-W Specification · DTU Overview
Manufacturer: Hunan Yanji Tech Co.,Ltd · Email: hi@yanjiiot.com

1 Port

2 Ports

4 Ports

8 Ports

Relay Output I/O Modules

Standard I/O Modules

Y202-W Standard WiFi DTU Technical Manual

Table of Contents

1. Introduction

2. System Overview

3. Hardware Interfaces

LED Behavior

4. Electrical Specifications

5. Serial Configuration & Packaging

5.1 UART Parameters

5.2 Packaging (AT+UARTTLn)

5.3 Modes

6. WiFi & Ethernet Networking

6.1 WiFi AP Mode (Default)

6.2 WiFi STA / AP+STA

6.3 Ethernet Mode

7. Socket Protocol Workflows

7.1 TCP Client / Server

7.2 UDP Client / Server

7.3 HTTP Client

7.4 MQTT Client

7.5 Registration Packets & Heartbeats

7.6 Peer-to-Peer (EDP)

8. Modbus Gateway & JSON Services

9. Advanced Functions

10. Remote Management & Diagnostics

11. AT Command Highlights

Y202-W Standard WiFi DTU Technical Manual ​

Table of Contents ​

1. Introduction ​

2. System Overview ​

3. Hardware Interfaces ​

LED Behavior ​

4. Electrical Specifications ​

5. Serial Configuration & Packaging ​

5.1 UART Parameters ​

5.2 Packaging (AT+UARTTLn) ​

5.3 Modes ​

6. WiFi & Ethernet Networking ​

6.1 WiFi AP Mode (Default) ​

6.2 WiFi STA / AP+STA ​

6.3 Ethernet Mode ​

7. Socket Protocol Workflows ​

7.1 TCP Client / Server ​

7.2 UDP Client / Server ​

7.3 HTTP Client ​

7.4 MQTT Client ​

7.5 Registration Packets & Heartbeats ​

7.6 Peer-to-Peer (EDP) ​

8. Modbus Gateway & JSON Services ​

9. Advanced Functions ​

10. Remote Management & Diagnostics ​

11. AT Command Highlights ​

Y202-W Standard WiFi DTU Technical Manual

Table of Contents

1. Introduction

2. System Overview

3. Hardware Interfaces

LED Behavior

4. Electrical Specifications

5. Serial Configuration & Packaging

5.1 UART Parameters

5.2 Packaging (AT+UARTTLn)

5.3 Modes

6. WiFi & Ethernet Networking

6.1 WiFi AP Mode (Default)

6.2 WiFi STA / AP+STA

6.3 Ethernet Mode

7. Socket Protocol Workflows

7.1 TCP Client / Server

7.2 UDP Client / Server

7.3 HTTP Client

7.4 MQTT Client

7.5 Registration Packets & Heartbeats

7.6 Peer-to-Peer (EDP)

8. Modbus Gateway & JSON Services

9. Advanced Functions

10. Remote Management & Diagnostics

11. AT Command Highlights