Table of Contents:

• 1.  Introduction
  • 1.1 ​ What is LTC2 LoRaWAN Temperature Transmitter
  • ​1.2  Features
  • 1.3 ​ Applications
  • 1.4 Hardware Change log
  • 1.5  Pin Definitions and Switch
    • 1.5.1  Jumper JP2 ( Power ON)
    • 1.5.2  LED
    • 1.5.3  PT100 Interfaces
    • 1.5.4  Reset Button
  • 1.6  Probe Variant
• 2.  How to use LTC2?
  • 2.1  Connect to PT100 sensors
  • 2.2  How it works?
  • 2.3  ​Quick guide to connect to LoRaWAN server (OTAA)
    • 2.3.1  Step 1: Create a device in TTN with the OTAA keys from LTC2
    • 2.3.2  Step 2: Power on LTC2
  • 2.4  ​Uplink Payload
    • BAT
    • Status & EXT
    • Channel 1 data and Channel 2 data
    • Unix TimeStamp
  • 2.5  Datalog Feature
    • 2.5.1  Unix TimeStamp
    • 2.5.2  Set Device Time
    • 2.5.3  Poll sensor value
    • 2.5.4  Datalog Uplink payload
  • 2.6  ​Alarm Mode
• 3.  Configure LTC2 via AT Command or LoRaWAN Downlink
  • 3.1  Set Transmit Interval Time
  • 3.2  Enable PT100 channels
  • 3.3  Set External Sensor Mode
  • 3.4  Quit AT Command
  • 3.5  Set system time
  • 3.6  Set Time Sync Mode
  • 3.7  Set Time Sync Interval
  • 3.8  Retrieve data
  • 3.9  Enable Alarm mode
  • 3.10  Alarm check time
  • 3.11  Set Alarm Threshold
  • 3.12  Set Calibrate Value
  • 3.13  Poll Calibrate Value
  • 3.14  Print data entries base on page
  • 3.15  Print last few data entries
  • 3.16  Clear Flash Record
• 4.  Battery & Power Consumption
• 5.  Firmware Change Log and Upload Firmware
• 6.  FAQ
  • 6.1  How to use AT Command to configure LTC2
  • 6.2  How to connect a customized PT100 cable?
  • 6.3  What is the frequency range of LTC2 LoRa part?
  • 6.4  How to change the LoRa Frequency Bands/Region
  • 6.5 How can I read sensor data without LoRaWAN? For Calibration Purpose
  • 6.6 LTC2 supported with 3-wire PT100
• 7.  Trouble Shooting
  • 7.1  AT Command input doesn't work
• 8.  Order Info
• 9. ​ Packing Info
• 10.  ​Support

1.  Introduction

1.1 ​ What is LTC2 LoRaWAN Temperature Transmitter

​1.2  Features

• LoRaWAN v1.0.3 Class A
• max: 2 x monitor temperature channels
• Support 3 -wire PT-100
• 8500mAh Li-SOCI2 Battery
• Firmware upgrade via console
• Wall Mountable
• Configurable via LoRa or UART
• Datalog and retrieve via LoRaWAN
• Use pre-load PT100 probe or 3rd PT100 probe
• Factory calibration for different resistance range
• Support accuracy measure of resistance and upload
• Battery Monitoring and upload
• Operation Temperature: -40 ~ 65 ℃

1.3 ​ Applications

• Logistics and Supply Chain Management
• Food management
• Cold chains solution
• Industrial Monitoring and Control

1.4 Hardware Change log

LTC2 v1.0: Release.

1.5  Pin Definitions and Switch

1.5.1  Jumper JP2 ( Power ON)

​​​​

Put a jumper on JP2 will power on the LTC2.

1.5.2  LED

The LED will flash in below case.

1.5.3  PT100 Interfaces

1.5.4  Reset Button

Press this button will reboot the LTC2

1.6  Probe Variant

LTC2 provide default probe version. See below for the variant:

2.  How to use LTC2?

2.1  Connect to PT100 sensors

LTC2 has different probe option provided for ordering, if user has LTC2 with probe, just skip this step. If user want to connect to a 3^rd party PT100 probe, please see CONNECT A 3^rd PARTY PT100 probe.

2.2  How it works?

2.3  ​Quick guide to connect to LoRaWAN server (OTAA)

​The DLOS8 is already set to connect to TTN . Rest we need to is register the LTC2 to TTN v3:​​​

2.4  ​Uplink Payload

Below is the uplink payload which shows.

• Poll Message Flag:      1: This message is a poll message reply, 0: means this is a normal uplink.
• Sync time OK:              1: Set time ok, 0: N/A. After time SYNC request is send, device will set this bit to 0 until got the time stamp from application server.
• Unix Time Request:     1: Request server downlink Unix time, 0 : N/A. In this mode, LTC2 will set this bit to 1 every 10 day to request a time SYNC. (AT+SYNCMOD to set this)
• EXT:                               The decode method for Channel 1 data and Channel 2 data
  • 0b(0001): Upload PT100 temperature, with 2 decimals, range:  -327.67 ~ 327.67 ℃
  • 0b(0010): Upload PT100 temperature, with 1 decimals, range:  -3276.7 ~ 3276.7 ℃
  • 0b(0011): Upload Resistance instead of Temperature, range:     -327.67~ 327.67 ohm

Refer to Datalog feature.

Example Uplink Payload:

Uplink payload example 1:  0CE9011422EC2D6073E83B

• Bat voltage:0x0CE9 =3305mV
• Ext=0x01
• Channel1 temp=0x1422/100=51.54 ℃
• Channel2 temp=(0xEC2D-65536)/100=-50.75 ℃
• System timestamp=0x6073E83B= 1618208827(UTC)

If payload is: EC2DH : (EC2D & 8000 == 1), temp = (EC2DH - 65536)/100 = -50.75 ℃

(EC2D & 8000: Judge whether the highest bit is 1, when the highest bit is 1, it is negative)

Uplink payload example 2:  0CED020203FE056073E697

• Bat voltage:0x0CED =3309mV
• Ext=0x02
• Channel1 temp=0x0203/10=515.4 ℃
• Channel2 temp=(0xFE05-65536)/10=-507.5 ℃
• System timestamp=0x6073E697=1618208407(UTC)

If payload is: FE05H :  (FE05 & 8000 == 1) , temp = (FE05H - 65536)/100 = 507.5 ℃

(EC2D & 8000: Judge whether the highest bit is 1, when the highest bit is 1, it is negative)

Uplink payload example 3 :  0CE9032EDE1F406073E967

• Bat voltage:0x0CE9 =3305mV
• Ext=0x03
• Channel1 res=0x2EDE/100=119.98 ohm
• Channel2 res=0x1F40/100=80.00 ohm
• System timestamp=0x6073E967= 1618209127(UTC)

​​​​​​

2.5  Datalog Feature

LTC2 will auto get the time from LoRaWAN server during Join, and each uplink will then include a timestamp. When user want to retrieve sensor value, user can send a poll command from the IoT platform to ask sensor to send value in the required time slot.

2.5.1  Unix TimeStamp

LTC2 uses Unix TimeStamp format based on

Users can get this time from the link:  https://www.epochconverter.com/ :

Below is the converter example

2.5.2  Set Device Time

2.5.3  Poll sensor value

Users can poll sensor values based on timestamps. Below is the downlink command.

2.5.4  Datalog Uplink payload

When server senser a datalog polling to LTC2, LTC2 will reply with one or more uplink messages as reply. Each uplink message includes multiply data entries value. Each entry has the same payload format as normal uplink payload.

Note:

• Poll Message Flag is set to 1.
• Each data entry is 11 bytes, to save airtime and battery, devices will send max bytes according to the current DR and Frequency bands.

For example, in US915 band, the max payload for different DR is:

1. DR0: max is 11 bytes so one entry of data
2. DR1: max is 53 bytes so devices will upload 4 entries of data (total 44 bytes)
3. DR2: total payload includes 11 entries of data
4. DR3: total payload includes 22 entries of data.

If devise doesn't have any data in the polling time. Device will uplink 11 bytes of 0    

Example:

If LTC2 has below data inside Flash:

If user send below downlink command: 3160A06E9060A098C00A

Where : Start time: 60A06E90 = time 21/5/16 01:00:00

             Stop time: 60A098C0 = time 21/5/16 04:00:00

LTC2 will uplink this payload.

0E64410B49800160A072B80E61410B3F800160A077680E61410B33800160A07C180E64410B2C800160A080C80E64410B28800160A085780E64410B24800160A08A280E64410B23800160A08ED80E64410B22800160A093880E64410B1E800160A09838

Where the first 11 bytes is for the first entry:

0E64410B49800160A072B8

Bat voltage: 0x0E64 =3684mV

poll message flag & Ext=0x41,means reply data,Ext=1

Channel1 temp=0x0B49/100=28.89℃

Channel2 temp=0x8001/100=-327.67℃

System timestamp=0x60A072B8= 1621127864(UTC)

2.6  ​Alarm Mode

3.  Configure LTC2 via AT Command or LoRaWAN Downlink

• AT Command Connection: See FAQ.

• LoRaWAN Downlink instruction for different platforms: IoT LoRaWAN Server

•  General Commands.

• General system settings like: uplink interval.

• LoRaWAN protocol & radio related command.

•  Commands special design for LTC2

​

3.1  Set Transmit Interval Time

Feature: Change LoRaWAN End Node Transmit Interval.

AT Command: AT+TDC

3.2  Enable PT100 channels

Feature: Enable PT100 channels. Default only Enable Channel 1

AT Command: AT+ENPTCHNUM

Downlink Command: 0xA1

Total bytes: 2 bytes

Example:

• 0xA101: same as AT+ENPTCHNUM =1
• 0xA102: same as AT+ENPTCHNUM =2

3.3  Set External Sensor Mode

Downlink Command: 0xA2

Total bytes: 2 bytes

Example:

• 0xA201: same as AT+EXT=1

3.4  Quit AT Command

Feature: Quit AT Command mode, so user need to input password again before use AT Commands.

AT Command: AT+DISAT

Downlink Command:

No downlink command for this feature.

3.5  Set system time

Feature: Set system time, unix format. See here for formmat detail.

AT Command:

Downlink Command:

0x306007806000    // Set timestamp to 0x(6007806000),Same as AT+TIMESTAMP=1611104352

3.6  Set Time Sync Mode

Feature: Enable/Disable Sync system time via LoRaWAN MAC Command (DeviceTimeReq), LoRaWAN server must support v1.0.3 protocol to reply this command.

SYNCMOD is set to 1 by default. If user want to set a different time from LoRaWAN server, user need to set this to 0.

AT Command:

Downlink Command:

0x28 01    // Same As AT+SYNCMOD=1

0x28 00    // Same As AT+SYNCMOD=0

3.7  Set Time Sync Interval

Feature: Define System time sync interval. SYNCTDC default value: 10 days.

AT Command:

Downlink Command:

0x29 0A      // Same as AT+SYNCTDC=0x0A

3.8  Retrieve data

Feature: Retrieval data for specify time slot.

AT Command:

No AT Command, only valid for downlink command.

Downlink Command:

See Poll Sensor Value.

3.9  Enable Alarm mode

Feature: Enable Alarm Mode.

AT Command: AT_WMOD

Total bytes: 2

Example:

0xA500: AT+WMOD=0(default)

0xA501: AT+WMOD=1(alarm mode)

Downlink Command:

See Poll Sensor Value.

3.10  Alarm check time

Feature: The time interval to check sensor value for Alarm.

AT Command: AT+CITEMP

Total bytes: 3

Example:

0xA60001: AT+CITEMP=1(default)

Set collection interval in 1min,only in alarm mode

Downlink Command:

See Poll Sensor Value.

3.11  Set Alarm Threshold

Feature: Set Alarm Threshold. 

AT Command: AT+ARTEMP

Total bytes: 9  Unit: ℃

Example:

A7FF380320FF380320

AT+ARTEMP=-200,800,-200,800

A7000A0064000A0065

AT+ARTEMP=10,100,10,101

Channel 1 operating temp:10~100

Channel 2 operating temp:10~101

Downlink Command:

See Poll Sensor Value.

3.12  Set Calibrate Value

Feature: Set Calibrate value for PT100 cable.  Detail of use of this command please see connect to a customized PT100 Probe.

AT Command: AT+RCABLE

Total bytes: 5

Example:

AT+RCABLE=296,300

Channel 1 rcable=0x0128/1000=0.296R

Channel 2 rcable=0x012C/1000=0.300R

Downlink Command:

0xA80128012C   -->  Same as AT+RCABLE=296,300

3.13  Poll Calibrate Value

Feature: Poll Calibrate value. LTC2 will reply with this command send an uplink to server.

AT Command: No AT Command.

Downlink Command:

Example: A901

End nodes will send racable config to server

Like uplink payload: 010128012C 

3.14  Print data entries base on page

Feature: Print the sector data from start page to stop page (max is 400 pages).

AT Command: AT+PDTA

Downlink Command:

No downlink commands for feature

3.15  Print last few data entries

Feature: Print the last few data entries

AT Command: AT+PLDTA

Downlink Command:

No downlink commands for feature

3.16  Clear Flash Record

Feature: Clear flash storage for data log feature.

AT Command: AT+CLRDTA

Downlink Command: 0xA3

• Example: 0xA301     //  Same as AT+CLRDTA

4.  Battery & Power Consumption

LTC2 uses ER26500 + SPC1520 battery pack. See below link for detail information about the battery info and how to replace.

Battery Info & Power Consumption Analyze .

5.  Firmware Change Log and Upload Firmware

• ST-LINK v2 GND      <-->  LTC2 GND

• ST-LINK v2 RESET    <-->  LTC2 NRST

• ST-LINK v2 SWCLK  <-->  LTC2 SWCLK

• ST-LINK v2 SWDIO  <-->  LTC2 SWDIO

• LTC2 power must be on.  

6.  FAQ

6.1  How to use AT Command to configure LTC2

LTC2 supports AT Command set. User can use a USB to TTL adapter plus the Program Cable to connect to LTC2 for using AT command, as below.

Connection:

• USB to TTL GND <-->  LTC2 GND

• USB to TTL RXD  <-->  LTC2 TXD

• USB to TTL TXD  <-->  LTC2 RXD

6.2  How to connect a customized PT100 cable?

We know that the Multimeter has a shortcut resistance 0.002 ohm.

Step 2: Measure the resistance between the two shorted wires of PT100 Probe.

As example, in this step, we check the shorted wire (both red) with 0.594 ohm, So we know that each wire of PT100 has (0.594-0.002)/2=0.296R (Where 0.002 is the value we got from step 1) .

Step 3: Run Calibrate Command.

Run this command to both channels to use 0.296R calibrate resistance.

AT+RCABLE=296,0   -->  Calibrate Channel 1 with 0.296R

Or use LoRaWAN downlink command (0xA8 Code) to set: 0xA801280000

User can use 0xA9 downlink command to poll the current calibration value.

Step 4: Connect the PT100 to LTC2

For a 3 wire PT100, there are two wire are shortcut, for example, as per above photo Channel 1, there are two red wire , which are shortcut in PT100, connect them as the photo. The 3^rd wire (white wire ) connect to the left pin of Channel -1.

6.3  What is the frequency range of LTC2 LoRa part?

Different LTC2 version supports different frequency range, below is the table for the working frequency and recommend bands for each model:

6.4  How to change the LoRa Frequency Bands/Region

You can follow the instructions for how to upgrade image.
When downloading the images, choose the required image file for download. ​

6.5 How can I read sensor data without LoRaWAN? For Calibration Purpose

Some clients need to calibrate the sensor value in calibration Lab. In such case, Reading the data without LoRaWAN network is more convenient. To achieve this, use can use a USB-TTL Adapter  to connect the LTC2 Motherboard's UART pins while still have the probe connected. See below. 

After there is UART Connection, reset the node.

Example output:

6.6 LTC2 supported with 3-wire PT100

The LTC2 uses the bridge method to measure temperature and supports the use of 3-wire PT100.

The difference between the wiring mode of three-wire PT100 and four-wire PT100 and the difference in the detection principle：

• Three wire PT100 adopts bridge method to measure data, and the relationship between the output temperature value and the output value of analog quantity.
• The four-wire PT100 has no bridge, is sent by constant current source, voltmeter measurement, and finally gives the measured resistance value.

Note: 2-wire PT100, current loop and voltage measurement loop combined in one, poor accuracy, not discussed.

7.  Trouble Shooting

7.1  AT Command input doesn't work

In the case if user can see the console output but can't type input to the device. Please check if you already include the ENTER while sending out the command. Some serial tool doesn't send ENTER while press the send key, user need to add ENTER in their string. 

8.  Order Info

Part Number : LTC2-XXX-YYY

XXX: Probe Version

• SI:   Standard IP68 probe x 1
• LT:  Low Temperature probe x 1
• HT: High Temperature probe x 1
• FSA:  Food Safety probe x 1
• FT:  Flat Type probe x 1
• NA: No probe

YYY: The default frequency band

• AS923 : LoRaWAN AS923 band
• AU915 : LoRaWAN AU915 band
• EU433 : LoRaWAN EU433 band
• EU868 : LoRaWAN EU868 band
• KR920 : LoRaWAN KR920 band
• US915 : LoRaWAN US915 band
• IN865 :  LoRaWAN IN865 band
• CN470 : LoRaWAN CN470 band

9. ​ Packing Info

Package Includes:

• LTC2 LoRaWAN Temperature Transmitter x 1

Dimension and weight:

• Device Size: cm
• Device Weight: g
• Package Size / pcs : cm
• Weight / pcs : g

10.  ​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.