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Y211-L Technical Manual ​

Y211-L

Y211-L Specification

Contents ​

  1. Overview
  2. Default Settings
  3. Serial Modes and Packetization
  4. LoRa Parameters and Communication Modes
  5. AT Command Conventions
  6. Common AT Commands
  7. Typical Configuration Flow
  8. Maintenance and Upgrade
  9. Troubleshooting

1. Overview ​

This manual explains parameter configuration and commissioning for the Y211-L LoRa DTU. Y211-L uses a serial AT command set, supports switching between transparent mode and command mode, and allows wireless, serial, and relay parameters to be configured from a host PC or MCU.

ItemDescription
Frequency Band410 to 493 MHz
Serial InterfaceSingle port, RS485 / RS232 / TTL depending on model
Typical RangeUp to about 10 km in open space
Maximum TX Power30 dBm
Working ModesBroadcast, fixed-point, master-slave, relay networking
Configuration MethodSerial AT commands

2. Default Settings ​

ParameterDefault
Serial Baud Rate115200 bps
Data Bits8
Stop Bits1
ParityNONE
Serial ModeTransparent mode
Base Frequency410 MHz
Step1 MHz
Channel0
Speed Level5
LoRa ModeBroadcast mode, BRD
Retransmission Count0
Retransmission Interval1000 ms
RelayOFF
Relay Group ID0
Relay Rule0,0

3. Serial Modes and Packetization ​

3.1 Serial Modes ​

Y211-L supports two serial working modes:

  • Transparent Mode, default: Serial data is packetized and forwarded through LoRa
  • AT Command Mode: Serial input is treated as AT commands and downlink data is not transparently forwarded

3.2 Entering AT Command Mode ​

Recommended sequence:

  1. Send +++
  2. Wait, 500 ms recommended and greater than the packet interval but less than 3 s
  3. Send a
  4. Enter AT mode after receiving +ok

Notes:

  • The device pauses data output for up to about 3 s after receiving +++
  • Only after +ok is returned can AT queries and settings be sent
  • AT mode is not saved across power cycles; the device returns to transparent mode after reboot

3.3 Exiting AT Mode ​

  • Send AT+EXIT\r\n and wait for OK
  • Or reboot the device directly

3.4 Packetization ​

Serial data is transmitted when either condition is met:

  • Length trigger: data length >= packet length, default 252, range 5 to 252
  • Interval trigger: inter-character gap >= packet interval, default 5 ms, range 0 to 300 ms

4. LoRa Parameters and Communication Modes ​

4.1 Key Parameters ​

ParameterMeaningDefault
Base Frequency, baseFrequency calculation baseline410 MHz
Step, stepFrequency interval between adjacent channels1 MHz
Channel, chWorking channel number0
Speed, spLoRa speed level, 1 to 9, higher is faster5
Key, keyLoRa encryption string, 1 to 16 charactersProject-specific
Device Address, idLocal address in fixed-point or master-slave mode0

Frequency formula: F = base + step x ch

4.2 Broadcast Mode, BRD ​

  • Data is broadcast only and not modified
  • Both ends must use the same base frequency, step, channel, and speed
  • No extra protocol framing is required

4.3 Fixed-Point Mode, FP ​

Transmit frame format in hex:

[Target Address(2B)][Target Channel(1B)][Data(nB)][XOR(1B)]

Examples:

  • Send to address 0x0001, channel 0x03, data 01 02 03: 00 01 03 01 02 03 02
  • If the target address is 0xFFFF, fixed-point mode can be used for broadcast transmission

4.4 Master-Slave Mode, MS ​

  • The master must frame data according to the master-slave protocol
  • Slave-to-master uplink can be sent transparently
  • Retransmission interval and retransmission count can be configured to reduce packet loss

Master transmit frame format:

[Target Address(2B)][Data(nB)]

4.5 Relay Networking ​

Key parameters:

  • AT+RELAY: relay enable
  • AT+GROUPID: relay group ID
  • AT+RELAYRULE: relay input and output rules

Typical rules:

  • The sender group ID must match the input rule of the first relay
  • The input rule of each relay must match the output rule of the previous relay
  • The receiver group ID must match the output rule of the last relay

5. AT Command Conventions ​

5.1 Command Format ​

  • Commands start with AT+ and end with \r or \n
  • Commands are case-insensitive, uppercase is recommended
  • Maximum command length is 256 bytes, 252 bytes recommended
  • Multiple parameters are separated by commas
  • Wait for the previous response before sending the next command, maximum timeout about 12 s

5.2 Call Types ​

TypeSend FormatReturn Format
QueryAT+CMD or AT+CMD?+CMD:value followed by OK
SetAT+CMD=value1,value2...OK
HelpAT+CMD=?+CMD:(range...) followed by OK

5.3 Common Error Codes ​

Error CodeMeaning
ARGSInvalid parameter, length, format, or range
ARGCInvalid number of parameters
CMD_UNKNOWNUnknown command
CMD_FORMATInvalid command format
CMD_LENGTHCommand too long
UN_VIEWWrite-only parameter
DEV_MEMORYMemory error
DEV_SAVEParameter save failed

6. Common AT Commands ​

6.1 Device and System ​

CommandFunctionNotes
AT+LISTList supported commandsPreferred for debugging
AT+VERQuery firmware versionReturns version string
AT+DEVINFOQuery device informationModel, version, SN, and more
AT+REBOOTReboot deviceParameters take effect in the current runtime area
AT+EXITExit AT modeReturns to transparent mode
AT+RSTCFGRestore backup parameters and rebootEquivalent to Reload
AT+BKCFGBack up current parametersRecommended after commissioning
AT+CLRCFGRestore factory parameters and rebootFull factory reset

6.2 Serial Parameters ​

CommandParameterRange / Default
AT+UART1=<baud>,<data>,<stop>,<parity>Serial settingsbaud 1200 to 460800, default 115200; data 7/8, default 8; stop 1/2, default 1; parity NONE/EVEN/ODD, default NONE
AT+UARTTL1=<tm>,<len>Packet interval and lengthtm 0 to 300 ms, default 5; len 5 to 252, default 252

6.3 Basic LoRa Parameters ​

CommandParameterRange / Default
AT+SPEED=<sp>LoRa speed level1 to 9, default 5
AT+KEY=<key>LoRa encryption string1 to 16 characters, write-only
AT+FREQ=<base>,<step>Base frequency and stepExample 4100,100, see note below
AT+CH=<ch>Channel numberDetermines frequency with base and step
AT+WMODE=<mode>LoRa modeBRD / FP / MS
AT+ADDR=<id>Local device address0 to 65535

Note: The AT+FREQ example uses a 100 kHz unit, so 4100 means 410.0 MHz.

6.4 Master-Slave and Relay Parameters ​

CommandParameterDefault
AT+TMODE=<mode>MASTER or SLAVEDepends on device role
AT+RETRANS=<time>,<count>Retransmission interval in ms and retransmission count1000,0
AT+RELAY=<state>ON / OFFOFF
AT+GROUPID=<id>Relay group ID, 0 to 2550
AT+RELAYRULE=<rule1>,<rule2>Relay input and output rules, 0 to 2550,0

7. Typical Configuration Flow ​

7.1 Quick Broadcast Configuration ​

  1. Enter AT mode, +++ -> delay -> a -> +ok
  2. Configure both devices with matching wireless parameters:
text
AT+FREQ=4100,100
AT+CH=0
AT+SPEED=5
AT+WMODE=BRD
  1. Set serial parameters if required:
text
AT+UART1=115200,8,1,NONE
AT+UARTTL1=5,252
  1. Save the configuration:
text
AT+BKCFG
  1. Reboot and verify the link:
text
AT+REBOOT

7.2 Fixed-Point Mode Configuration ​

  1. Set both ends to the same band and speed:
text
AT+FREQ=4100,100
AT+SPEED=5
  1. Set device addresses:
text
AT+ADDR=1
AT+ADDR=2
  1. Switch to fixed-point mode:
text
AT+WMODE=FP
  1. Send data using the fixed-point frame format.

7.3 Master-Slave Mode Configuration ​

  1. Match the base wireless parameters on both devices.
  2. On the master, set AT+WMODE=MS and AT+TMODE=MASTER.
  3. On the slave, set AT+WMODE=MS and AT+TMODE=SLAVE.
  4. Set retransmission strategy if needed:
text
AT+RETRANS=1000,0
  1. The master sends framed master-slave messages and the slave returns data transparently.

7.4 Relay Networking Suggestions ​

  1. Complete the base communication mode configuration first, broadcast, fixed-point, or master-slave.
  2. Enable relay on each node with AT+RELAY=ON.
  3. Build the group ID and relay rule chain:
  • Sender group ID = first relay input rule
  • First relay output rule = second relay input rule
  • Receiver group ID = last relay output rule
  1. After validating the multi-hop link, run AT+BKCFG to save.

8. Maintenance and Upgrade ​

8.1 Parameter Partitions ​

The device uses three parameter areas:

  • Runtime Area: Current running configuration
  • Backup Area: Saved by AT+BKCFG
  • Factory Area: Factory-fixed default parameters

Recommended workflow:

  1. Finish parameter commissioning.
  2. Run AT+BKCFG to create a backup.
  3. Use AT+RSTCFG when rollback is needed.
  4. Use AT+CLRCFG for a full factory reset.

8.2 Firmware Upgrade ​

Upgrade steps:

  1. Power off the device.
  2. Hold the Reload button while powering on and release it after about 3 s to enter upgrade mode.
  3. Select the firmware file in the host-side tool and start the upgrade.

Firmware upgrade normally does not affect saved parameters, but backing up parameters first is still recommended.

9. Troubleshooting ​

SymptomPossible CauseRecommended Action
Cannot enter AT modeThe timing is incorrect or +ok was not receivedRetry with +++ -> 500 ms delay -> a
Command returns CMD_FORMATThe command does not start with AT+ or has no line endingCheck command format and serial line ending
Command returns ARGS/ARGCWrong parameter value or parameter countRun AT+CMD=? to view the valid range
LoRa link does not workFrequency, step, channel, or speed does not matchCheck FREQ / CH / SPEED on both ends
Fixed-point communication failsWrong target address or wrong frame formatCheck ADDR and the fixed-point frame format with XOR
Packet loss in master-slave modeRetransmission is not configured or the link is noisyIncrease RETRANS interval and adjust count
Relay link breaksGroup ID and rule chain do not matchCheck GROUPID and RELAYRULE across all hops
Parameters are lost after rebootBackup was not executedRun AT+BKCFG after configuration

Quick LED reference:

  • Power steady on: power is normal
  • WORK regular blinking: module is running normally
  • TX blinking: LoRa packet transmission
  • RX blinking: LoRa packet reception
  • Manufacturer: Hunan YenGear Tech Co., Ltd.
  • Address: Room 21014, Building 1, Fudi Xingguang Tiandi, Yingxin Road, Yuhua District, Changsha, Hunan, China
  • Email: hi@yengear.com
  • Website: www.yengear.com