RS485-LN – RS485 to LoRaWAN Converter User Manual

Table of Contents:

1.Introduction

1.1 What is RS485-LN RS485 to LoRaWAN Converter

1.2 Specifications

Hardware System:

• STM32L072CZT6 MCU
• SX1276/78 Wireless Chip  
• Power Consumption (exclude RS485 device):
  • Idle: 32mA@12v
  • 20dB Transmit: 65mA@12v

Interface for Model:

• RS485
• Power Input 7~ 24V DC.  

LoRa Spec:

• Frequency Range:
  • Band 1 (HF): 862 ~ 1020 Mhz
  • Band 2 (LF): 410 ~ 528 Mhz
• 168 dB maximum link budget.
• +20 dBm - 100 mW constant RF output vs.
• +14 dBm high efficiency PA.
• Programmable bit rate up to 300 kbps.
• High sensitivity: down to -148 dBm.
• Bullet-proof front end: IIP3 = -12.5 dBm.
• Excellent blocking immunity.
• Low RX current of 10.3 mA, 200 nA register retention.
• Fully integrated synthesizer with a resolution of 61 Hz.
• FSK, GFSK, MSK, GMSK, LoRaTM and OOK modulation.
• Built-in bit synchronizer for clock recovery.
• Preamble detection.
• 127 dB Dynamic Range RSSI.
• Automatic RF Sense and CAD with ultra-fast AFC.
• Packet engine up to 256 bytes with CRC.

1.3 Features

• LoRaWAN Class A & Class C protocol (default Class C)
• Frequency Bands: CN470/EU433/KR920/US915/EU868/AS923/AU915/IN865/RU864
• AT Commands to change parameters
• Remote configure parameters via LoRa Downlink
• Firmware upgradable via program port
• Support multiply RS485 devices by flexible rules
• Support Modbus protocol
• Support Interrupt uplink (Since hardware version v1.2)

1.4 Applications

• Smart Buildings & Home Automation
• Logistics and Supply Chain Management
• Smart Metering
• Smart Agriculture
• Smart Cities
• Smart Factory

1.5 Firmware Change log

RS485-LN Image files – Download link and Change log

1.6 Hardware Change log

2. Power ON Device

3. Operation Mode

3.1 How it works?

3.2 Example to join LoRaWAN network

Here shows an example for how to join the TTN V3 Network. Below is the network structure, we use LG308 as LoRaWAN gateway here.  

You can also choose to create the device manually.

Add APP KEY and DEV EUI

3.3 Configure Commands to read data

3.3.1 onfigure UART settings for RS485 or TTL communication

To use RS485-LN to read data from RS485 sensors, connect the RS485-LN A/B traces to the sensors. And user need to make sure RS485-LN use the match UART setting to access the sensors. The related commands for UART settings are:

3.3.2 Configure sensors

3.3.3 Configure read commands for each sampling

• AT+DATACUT

• AT+SEARCH

Examples:

Below are examples for the how above AT Commands works.

AT+COMMANDx : This command will be sent to RS485/TTL devices during each sampling, Max command length is 14 bytes. The grammar is:

Examples:

1. For a return string from AT+COMMAND1: 16 0c 1e 56 34 2e 30 58 5f 36 41 30 31 00 49

If we set AT+SEARCH1=1,1E 56 34.      (max 5 bytes for prefix)

The valid data will be all bytes after 1E 56 34 , so it is  2e 30 58 5f 36 41 30 31 00 49

2. For a return string from AT+COMMAND1:  16 0c 1e 56 34 2e 30 58 5f 36 41 30 31 00 49

If we set AT+SEARCH1=2, 1E 56 34+31 00 49

Device will search the bytes between 1E 56 34 and 31 00 49. So it is  2e 30 58 5f 36 41 30

AT+DATACUTx : This command defines how to handle the return from AT+COMMANDx, max return length is 45 bytes.

Examples:

• Grab bytes:

• Grab a section.

• Grab different sections.

Note:

AT+SEARCHx and AT+DATACUTx can be used together, if both commands are set, RS485-BL will first process AT+SEARCHx on the return string and get a temporary string, and then process AT+DATACUTx on this temporary string to get the final payload. In this case, AT+DATACUTx need to set to format AT+DATACUTx=0,xx,xx where the return bytes set to 0.

Example:

AT+COMMAND1=11 01 1E D0,0

AT+SEARCH1=1,1E 56 34

AT+DATACUT1=0,2,1~5

Return string from AT+COMMAND1: 16 0c 1e 56 34 2e 30 58 5f 36 41 30 31 00 49

String after SEARCH command: 2e 30 58 5f 36 41 30 31 00 49

Valid payload after DataCUT command: 2e 30 58 5f 36

3.3.4 Compose the uplink payload

Examples: AT+DATAUP=1

Compose the uplink payload with value returns in sequence and send with Multiply UPLINKs.

Final Payload is

Battery Info+PAYVER + PAYLOAD COUNT + PAYLOAD# + DATA

1. Battery Info (2 bytes): Battery voltage
2. PAYVER (1 byte): Defined by AT+PAYVER
3. PAYLOAD COUNT (1 byte): Total how many uplinks of this sampling.
4. PAYLOAD# (1 byte): Number of this uplink. (from 0,1,2,3…,to PAYLOAD COUNT)
5. DATA: Valid value: max 6 bytes(US915 version here, Notice*!) for each uplink so each uplink <= 11 bytes. For the last uplink, DATA will might less than 6 bytes

So totally there will be 3 uplinks for this sampling, each uplink includes 6 bytes DATA

DATA1=RETURN1 Valid Value = 20 20 0a 33 90 41

DATA2=1^st ~ 6^th byte of Valid value of RETURN10= 02 aa 05 81 0a 20

DATA3=7^th ~ 11^th bytes of Valid value of RETURN10 = 20 20 20 2d 30

Below are the uplink payloads:

Notice: the Max bytes is according to the max support bytes in different Frequency Bands for lowest SF. As below:

   * For AU915/AS923 bands, if UplinkDwell time=0, max 51 bytes for each uplink ( so 51 -5 = 46 max valid date) 

   * For AU915/AS923 bands, if UplinkDwell time=1, max 11 bytes for each uplink ( so 11 -5 = 6 max valid date). 

   * For US915 band, max 11 bytes for each uplink ( so 11 -5 = 6 max valid date). 

   * For all other bands: max 51 bytes for each uplink  ( so 51 -5 = 46 max valid date). 

3.3.5 Uplink on demand

Except uplink periodically, RS485-BL is able to uplink on demand. The server sends downlink command to RS485-BL and RS485 will uplink data base on the command.

Downlink control command:

0x08 command: Poll an uplink with current command set in RS485-BL.

0xA8 command: Send a command to RS485-BL and uplink the output from sensors.

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   1. 
      
      1. Uplink on Interrupt

Put the interrupt sensor between 3.3v_out and GPIO ext.

AT+INTMOD=0  Disable Interrupt

AT+INTMOD=1  Interrupt trigger by rising or falling edge.

AT+INTMOD=2  Interrupt trigger by falling edge. ( Default Value)

AT+INTMOD=3  Interrupt trigger by rising edge.

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   1. Uplink Payload

Below is the decoder for the first 3 bytes. The rest bytes are dynamic depends on different RS485 sensors.

function Decoder(bytes, port) {

//Payload Formats of RS485-BL Deceive

return {

    //Battery,units:V

    BatV(bytes[0]<<8 | bytes[1])&0x7fff)/1000,

    //GPIO_EXTI  

    EXTI_Triggerbytes[0] & 0x80)? "TRUE":"FALSE",

    //payload of version

    Pay_ver:bytes[2],

    }; 

  }

TTN V3 uplink screen shot.

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   1. Configure RS485-BL via AT or Downlink

User can configure RS485-BL via AT Commands or LoRaWAN Downlink Commands

There are two kinds of Commands:

• Common Commands: They should be available for each sensor, such as: change uplink interval, reset device. For firmware v1.3, user can find what common commands it supports: http://wiki.dragino.com/index.php?title=End_Device_AT_Commands_and_Downlink_Commands

• Sensor Related Commands: These commands are special designed for RS485-BL.  User can see these commands below:

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   1. 
      
      1. Common Commands:

They should be available for each of Dragino Sensors, such as: change uplink interval, reset device. For firmware v1.3, user can find what common commands it supports: http://wiki.dragino.com/index.php?title=End_Device_AT_Commands_and_Downlink_Commands

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   1. 
      
      1. Sensor related commands:

Choose Device Type (RS485 or TTL)

RS485-BL can connect to either RS485 sensors or TTL sensor. User need to specify what type of sensor need to connect.

• AT Command

AT+MOD=1 // Set to support RS485-MODBUS type sensors. User can connect multiply RS485 , Modbus sensors to the A / B pins.

AT+MOD=2 // Set to support TTL Level sensors, User can connect one TTL Sensor to the TXD/RXD/GND pins.

• Downlink Payload

0A aa     à same as AT+MOD=aa

RS485 Debug Command (AT+CFGDEV)

This command is used to configure the RS485 or TTL sensors; they won’t be used during sampling.

• AT Command

AT+CFGDEV=xx xx xx xx xx xx xx xx xx xx xx xx,m

m: 0: no CRC; 1: add CRC-16/MODBUS in the end of this command.

• Downlink Payload

Format: A8 MM NN XX XX XX XX YY

Where:

• MM: 1: add CRC-16/MODBUS ; 0: no CRC
• NN: The length of RS485 command
• XX XX XX XX: RS485 command total NN bytes
• YY: How many bytes will be uplink from the return of this RS485 command, if YY=0, RS485-BL will execute the downlink command without uplink; if YY>0, RS485-BL will uplink total YY bytes from the output of this RS485 command

Example 1:

To connect a Modbus Alarm with below commands.

• The command to active alarm is: 0A 05 00 04 00 01 4C B0. Where 0A 05 00 04 00 01 is the Modbus command to read the register 00 40 where stored the DI status. The 4C B0 is the CRC-16/MODBUS which calculate manually.

• The command to deactivate alarm is: 0A 05 00 04 00 00 8D 70. Where 0A 05 00 04 00 00 is the Modbus command to read the register 00 40 where stored the DI status. The 8D 70 is the CRC-16/MODBUS which calculate manually.

So if user want to use downlink command to control to RS485 Alarm, he can use:

A8 01 06 0A 05 00 04 00 01 00: to activate the RS485 Alarm

A8 01 06 0A 05 00 04 00 00 00: to deactivate the RS485 Alarm

A8 is type code and 01 means add CRC-16/MODBUS at the end, the 3^rd byte is 06, means the next 6 bytes are the command to be sent to the RS485 network, the final byte 00 means this command don’t need to acquire output.

Example 2:

Check TTL Sensor return:

Set Payload version

This is the first byte of the uplink payload. RS485-BL can connect to different sensors. User can set the PAYVER field to tell server how to decode the current payload.

• AT Command:

AT+PAYVER: Set PAYVER field = 1

• Downlink Payload:

0xAE 01   à Set PAYVER field =  0x01

0xAE 0F   à Set PAYVER field =  0x0F

Set RS485 Sampling Commands

AT+COMMANDx, AT+DATACUTx and AT+SEARCHx

These three commands are used to configure how the RS485-BL polling data from Modbus device. Detail of usage please see : polling RS485 device. 

• AT Command:

AT+COMMANDx: Configure RS485 read command to sensor.

AT+DATACUTx: Configure how to handle return from RS485 devices.

AT+SEARCHx: Configure search command

• Downlink Payload:

0xAF downlink command can be used to set AT+COMMANDx or AT+DATACUTx.

Note: if user use AT+COMMANDx to add a new command, he also need to send AT+DATACUTx downlink.

Format: AF MM NN LL XX XX XX XX YY

Where:

• MM: the ATCOMMAND or AT+DATACUT to be set. Value from 01 ~ 0F,
• NN: 0: no CRC; 1: add CRC-16/MODBUS ; 2: set the AT+DATACUT value.
• LL: The length of AT+COMMAND or AT+DATACUT command
• XX XX XX XX: AT+COMMAND or AT+DATACUT command
• YY: If YY=0, RS485-BL will execute the downlink command without uplink; if YY=1, RS485-BL will execute an uplink after got this command. 

Example:

AF 03 01 06 0A 05 00 04 00 01 00: Same as AT+COMMAND3=0A 05 00 04 00 01,1

AF 03 02 06 10 01 05 06 09 0A 00: Same as AT+DATACUT3=16,1,5+6+9+10

AF 03 02 06 0B 02 05 07 08 0A 00: Same as AT+DATACUT3=11,2,5~7+8~10

0xAB downlink command can be used for set AT+SEARCHx

Example: AB aa 01 03 xx xx xx (03 here means there are total 3 bytes after 03) So

• AB aa 01 03 xx xx xx  same as AT+SEARCHaa=1,xx xx xx
• AB aa 02 03 xx xx xx 02 yy yy(03 means there are 3 bytes after 03, they are xx xx xx;02 means there are 2 bytes after 02, they are yy yy) so the commands

AB aa 02 03 xx xx xx 02 yy yy  same as AT+SEARCHaa=2,xx xx xx+yy yy

Fast command to handle MODBUS device

AT+MBFUN is valid since v1.3 firmware version. The command is for fast configure to read Modbus devices. It is only valid for the devices which follow the MODBUS-RTU protocol.

This command is valid since v1.3 firmware version

AT+MBFUN has only two value:

• AT+MBFUN=1: Enable Modbus reading. And get response base on the MODBUS return

AT+MBFUN=1, device can auto read the Modbus function code: 01, 02, 03 or 04. AT+MBFUN has lower priority vs AT+DATACUT command. If AT+DATACUT command is configured, AT+MBFUN will be ignore.

• AT+MBFUN=0: Disable Modbus fast reading.

Example:

• AT+MBFUN=1 and AT+DATACUT1/AT+DATACUT2 are not configure (0,0,0).
• AT+COMMAND1= 01 03 00 10 00 08,1 --> read slave address 01 , function code 03, start address 00 01, quantity of registers 00 08.
• AT+COMMAND2= 01 02 00 40 00 10,1 --> read slave address 01 , function code 02, start address 00 40, quantity of inputs 00 10.

• Downlink Commands:

A9 aa -à Same as AT+MBFUN=aa

RS485 command timeout

Some Modbus device has slow action to send replies. This command is used to configure the RS485-BL to use longer time to wait for their action.

Default value: 0, range:  0 ~ 5 seconds

• AT Command:

AT+CMDDLaa=hex(bb cc)

Example:

AT+CMDDL1=1000 to send the open time to 1000ms

• Downlink Payload:

0x AA aa bb cc

Same as: AT+CMDDLaa=hex(bb cc)

   Example:

   0xAA 01 03 E8  à Same as AT+CMDDL1=1000 ms

Uplink payload mode

Define to use one uplink or multiple uplinks for the sampling.

The use of this command please see: Compose Uplink payload

• AT Command:

AT+DATAUP=0

AT+DATAUP=1

• Downlink Payload:

0xAD 00   à Same as AT+DATAUP=0

0xAD 01   à Same as AT+DATAUP=1

Manually trigger an Uplink

Ask device to send an uplink immediately.

• Downlink Payload:

0x08 FF, RS485-BL will immediately send an uplink.

Clear RS485 Command

The AT+COMMANDx and AT+DATACUTx settings are stored in special location, user can use below command to clear them.

• AT Command:

AT+CMDEAR=mm,nn   mm: start position of erase ,nn: stop position of erase

Etc. AT+CMDEAR=1,10 means erase AT+COMMAND1/AT+DATACUT1 to AT+COMMAND10/AT+DATACUT10

Example screen shot after clear all RS485 commands.  

The uplink screen shot is:

• Downlink Payload:

0x09 aa bb  same as AT+CMDEAR=aa,bb

Set Serial Communication Parameters

Set the Rs485 serial communication parameters:

• AT Command:

Set Baud Rate:

AT+BAUDR=9600    // Options: (1200,2400,4800,14400,19200,115200)

Set UART parity

AT+PARITY=0    // Option: 0: no parity, 1: odd parity, 2: even parity

Set STOPBIT

AT+STOPBIT=0    // Option: 0 for 1bit; 1 for 1.5 bit ; 2 for 2 bits

• Downlink Payload:

A7 01 aa bb: Same  AT+BAUDR=hex(aa bb)*100

Example:

• A7 01 00 60   same as AT+BAUDR=9600
• A7 01 04 80     same as AT+BAUDR=115200

A7 02 aa: Same as  AT+PARITY=aa  (aa value: 00 , 01 or 02)

A7 03 aa: Same as  AT+STOPBIT=aa  (aa value: 00 , 01 or 02)

Control output power duration

User can set the output power duration before each sampling.

• AT Command:

Example:

AT+3V3T=1000 // 3V3 output power will open 1s before each sampling.

AT+5VT=1000 // +5V output power will open 1s before each sampling.

• LoRaWAN Downlink Command:

07 01 aa bb  Same as AT+5VT=(aa bb)

07 02 aa bb  Same as AT+3V3T=(aa bb)

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   1. Buttons

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   1. +3V3 Output

RS485-BL has a Controllable +3V3 output, user can use this output to power external sensor.

The +3V3 output will be valid for every sampling. RS485-BL will enable +3V3 output before all sampling and disable the +3V3 after all sampling.  

The +3V3 output time can be controlled by AT Command.

AT+3V3T=1000

Means set +3v3 valid time to have 1000ms. So, the real +3v3 output will actually have 1000ms + sampling time for other sensors.

By default, the AT+3V3T=0. This is a special case, means the +3V3 output is always on at any time

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   1. +5V Output

RS485-BL has a Controllable +5V output, user can use this output to power external sensor.

The +5V output will be valid for every sampling. RS485-BL will enable +5V output before all sampling and disable the +5v after all sampling.  

The 5V output time can be controlled by AT Command.

AT+5VT=1000

Means set 5V valid time to have 1000ms. So, the real 5V output will actually have 1000ms + sampling time for other sensors.

By default, the AT+5VT=0. If the external sensor which require 5v and require more time to get stable state, user can use this command to increase the power ON duration for this sensor.

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   1. LEDs

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   1. Switch Jumper

+3.3V: is always ON

+5V: Only open before every sampling. The time is by default, it is AT+5VT=0.  Max open time. 5000 ms.

1. Case Study

User can check this URL for some case studies.

http://wiki.dragino.com/index.php?title=APP_RS485_COMMUNICATE_WITH_SENSORS

1. Use AT Command
   1. Access AT Command

RS485-BL supports AT Command set. User can use a USB to TTL adapter plus the 3.5mm Program Cable to connect to RS485-BL to use AT command, as below.

In PC, User needs to set serial tool(such as putty, SecureCRT) baud rate to 9600 to access to access serial console of RS485-BL. The default password is 123456. Below is the output for reference:

More detail AT Command manual can be found at AT Command Manual

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   1. Common AT Command Sequence
      1. Multi-channel ABP mode (Use with SX1301/LG308)

If device has not joined network yet:

AT+FDR

AT+NJM=0

ATZ

If device already joined network:

AT+NJM=0

ATZ

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      1. Single-channel ABP mode (Use with LG01/LG02)

AT+FDR   Reset Parameters to Factory Default, Keys Reserve

AT+NJM=0 Set to ABP mode

AT+ADR=0 Set the Adaptive Data Rate Off

AT+DR=5  Set Data Rate

AT+TDC=60000  Set transmit interval to 60 seconds

AT+CHS=868400000 Set transmit frequency to 868.4Mhz

AT+RX2FQ=868400000 Set RX2Frequency to 868.4Mhz (according to the result from server)

AT+RX2DR=5  Set RX2DR to match the downlink DR from server. see below

AT+DADDR=26 01 1A F1 Set Device Address to 26 01 1A F1, this ID can be found in the LoRa Server portal.

ATZ          Reset MCU

Note:

1. Make sure the device is set to ABP mode in the IoT Server.
2. Make sure the LG01/02 gateway RX frequency is exactly the same as AT+CHS setting.
3. Make sure SF / bandwidth setting in LG01/LG02 match the settings of AT+DR. refer this link to see what DR means.
4. The command AT+RX2FQ and AT+RX2DR is to let downlink work. to set the correct parameters, user can check the actually downlink parameters to be used. As below. Which shows the RX2FQ should use 868400000 and RX2DR should be 5

1. FAQ
   1. How to upgrade the image?

The RS485-BL LoRaWAN Controller is shipped with a 3.5mm cable, the cable is used to upload image to RS485-BL to:

• Support new features
• For bug fix
• Change LoRaWAN bands.

Below shows the hardware connection for how to upload an image to RS485-BL:

Step1: Download flash loader.

Step2: Download the LT Image files.

Step3: Open flashloader; choose the correct COM port to update.

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   1. How to change the LoRa Frequency Bands/Region?

User can follow the introduction for how to upgrade image. When download the images, choose the required image file for download.

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   1. How many RS485-Slave can RS485-BL connects?

The RS485-BL can support max 32 RS485 devices. Each uplink command of RS485-BL can support max 16 different RS485 command. So RS485-BL can support max 16 RS485 devices pre-program in the device for uplink. For other devices no pre-program, user can use the downlink message (type code 0xA8) to poll their info.

1. Trouble Shooting     
   1. Downlink doesn’t work, how to solve it?

Please see this link for debug:

http://wiki.dragino.com/index.php?title=Main_Page#LoRaWAN_Communication_Debug  

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   1. Why I can’t join TTN V3 in US915 /AU915 bands?

It might about the channels mapping. Please see for detail.

http://wiki.dragino.com/index.php?title=LoRaWAN_Communication_Debug#Notice_of_US915.2FCN470.2FAU915_Frequency_band

1. Order Info

Part Number: RS485-BL-XXX

XXX:

• EU433: frequency bands EU433
• EU868: frequency bands EU868
• KR920: frequency bands KR920
• CN470: frequency bands CN470
• AS923: frequency bands AS923
• AU915: frequency bands AU915
• US915: frequency bands US915
• IN865: frequency bands IN865
• RU864: frequency bands RU864
• KZ865: frequency bands KZ865

1. Packing Info

Package Includes:

• RS485-BL x 1
• Stick Antenna for LoRa RF part x 1
• Program cable x 1

Dimension and weight:

• Device Size: 13.5 x 7 x 3 cm
• Device Weight: 105g
• Package Size / pcs : 14.5 x 8 x 5 cm
• Weight / pcs : 170g

1. Support

• Support is provided Monday to Friday, from 09:00 to 18:00 GMT+8. Due to different timezones we cannot offer live support. However, your questions will be answered as soon as possible in the before-mentioned schedule.
• Provide as much information as possible regarding your enquiry (product models, accurately describe your problem and steps to replicate it etc) and send a mail to

support@dragino.com