Long Range Wireless Thermocouple High Temperature Sensor

This long range wireless thermocouple temperature sensor was designed as a low-cost industrial solution with high accuracy and reliability.  This wireless sensor may be powered one of two ways, depending on your application requirements.  For those who require battery operated thermocouple temperature sensing, this sensor may be jumper configured for operation from 2 AA batteries, providing a long life of 300K to 400K transmissions or 5 to 8 years.   Optionally, this sensor may be powered from an external power supply by changing the power jumper, allowing for use with a 5 to 12VDC external power supply.  This wireless sensor offers up to 28 miles of range when used with large outdoor high-gain antennas and a clear line of sight.  Using the included antenna, users can expect 1 to 2 miles of reliable operation in clear line of sight applications.  In urban installations, and inside building, users may achieve up to 1,000 feet of communications, depending on installation location and building materials.  This sensor is compatible with select wireless mesh networks and gateways, allowing data to hop from this sensor to repeater stations to achieve longer range.  This sensor is very easy to interface to a PC computer, Particle Photon, Particle Electron, Onion Omega, or Raspberry Pi.  Receiving data generated by this sensor requires the use of a USB wireless modem or a embedded microcontroller that supports DigiMeshⓇ 900HP-S3B wireless communications.  If you would like to learn more about DigiMeshⓇ, please visit www.digi.com.

Wireless Sensor Modes

This wireless wireless thermocouple sensor transmitter has 2 modes of operation: run mode and configuration mode.   Run mode is used for daily operation.  In this mode, the sensor wakes up, sends data, and goes back to sleep based on a user predefined interval.  By default, this transmission occurs every 10 minutes.  Users may change this interval using a 32-bit value indicating the number of seconds between transmissions.  In configuration mode, important parameters of the sensor may be changed.  Parameters include security options (encryption security key), transmission interval, PAN ID, Output Transmission Power, Node ID, and the number of retries in the event transmission is unsuccessful.

Run Mode – Sensor Data Structure

In the run mode the sensor will wake up after the predefined sleep time and will send a data packet over the wireless network. The data packet structure will look like this:

7E, 00, 19, 90, 00, 13, A2, 00, 41, 68, 63, BA, FF, FE, C2, 7F, 01, 01, 03, FF, 05, 00, 04, 00, 01, A4, 00, 00, 10

To receive data from a wireless sensor, a USB Wireless Modem is required, and should be configured to communicate data to your PC using API mode.  API mode generates a complete data frame with complete identification data of sensors along with checksum values.

Packet Organization

A complete packet consists of a Payload wrapped in a 900HP-S3B API frame.  The entire group of bytes for each transmission is defined as the 900HP-S3B API frame.  The Payload is the data generated by our sensor.  We will define each byte of the API Frame so you can see how it all works together:

0x7E {Byte 1 – 900HP-S3B API Structure} – Header Byte, this byte is fixed and never changes.

0x00 {Byte 2 – 900HP-S3B API Structure} – MSB Number of Bytes in the Data Frame, this Value will always be 0 for this sensor.

0x19 {Byte 3 – 900HP-S3B API Structure} – LSB Number of Bytes in the Data Frame, this Value will always be 0x19 (25 Bytes) for this sensor.

0x90 {Byte 4 – 900HP-S3B API Structure} – Frame Type – This Value will not Change

0x00 {Byte 5 – 900HP-S3B API Structure} – Frame ID 0 = No Response Frame – This Value will not Change

0x13 {Byte 6 – 900HP-S3B API Structure} – Serial Number Byte 1 of Transmitter, This Value is Defined by Each Sensor in the Network, Though this Particular Value Does Not Usually Change

0xA2 {Byte 7 – 900HP-S3B API Structure} – Serial Number Byte 2 of Transmitter, This Value is Defined by Each Sensor in the Network, Though this Particular Value Does Not Usually Change

0x00 {Byte 8 – 900HP-S3B API Structure} – Serial Number Byte 3 of Transmitter, This Value is Defined by Each Sensor in the Network, Though this Particular Value Does Not Usually Change

0x41 {Byte 9 – 900HP-S3B API Structure} – Serial Number Byte 4 of Transmitter, This Value is Defined by Each Sensor in the Network, Though this Particular Value Does Not Usually Change

0x68 {Byte 10 – 900HP-S3B API Structure} – Serial Number Byte 5 of Transmitter, This Value is Defined by Each Sensor in the Network

0x63 {Byte 11 – 900HP-S3B API Structure} – Serial Number Byte 6 of Transmitter, This Value is Defined by Each Sensor in the Network

0xBA {Byte 12 – 900HP-S3B API Structure} – Serial Number Byte 7 of Transmitter, This Value is Defined by Each Sensor in the Network

0xFF {Byte 13 – 900HP-S3B API Structure} – Serial Number Byte 8 of Transmitter, This Value is Defined by Each Sensor in the Network

0xFE {Byte 14 – 900HP-S3B API Structure} – This Value will not Change

0xC2 {Byte 15 – 900HP-S3B API Structure} – This Value will not Change

0x7F {Byte 16 – 900HP-S3B API Structure – Payload Data[1]} === Payload Header byte, this byte is fixed and never changes.

0x01 {Byte 17 – 900HP-S3B API Structure – Payload Data[2]} === Node ID, this is a user programmable value that may be used to identify the sensor number.  Node ID is programmable in configuration mode.

0x01 {Byte 18 – 900HP-S3B API Structure – Payload Data[3]} === Thermocouple Temperature Sensor Firmware Version, 0x01 is the Release Version

0x03 {Byte 19 – 900HP-S3B API Structure – Payload Data[4]} === Battery Voltage MSB, This Value will Change based on the available Battery Life

0x63 {Byte 20 – 900HP-S3B API Structure – Payload Data[5]} === Battery Voltage LSB, This Value will Change based on the available Battery Life

0x63 {Byte 21 – 900HP-S3B API Structure – Payload Data[6]} === Data Transmit Counter, this value will constantly Increase after each Transmission from 0x00 to 0xFF.  This may be used to help identify missed transmissions.

0x00 {Byte 22 – 900HP-S3B API Structure – Payload Data[7]} === This byte is used to define the sensor type MSB, this thermocouple sensor id value will always be 0x00.

0x04 {Byte 23 – 900HP-S3B API Structure – Payload Data[8]} === This byte is used to define the sensor type LSB, this thermocouple sensor id value will always be 0x04.

0x03 {Byte 24 – 900HP-S3B API Structure – Payload Data[9]} === Reserved

0x01 {Byte 25 – 900HP-S3B API Structure – Payload Data[10]} === Temperature MSB

0xA4 {Byte 26 – 900HP-S3B API Structure – Payload Data[11]} === Temperature LSB

0x00 {Byte 27 – 900HP-S3B API Structure – Payload Data[12]} ===

0x00 {Byte 28 – 900HP-S3B API Structure – Payload Data[13]} ===

0x10 {Byte 29 – 900HP-S3B API Structure – Checksum = 255 – (8-Bit Sum of Bytes 4 through 28)

 

To convert raw data values into temperature humidity values, use the following formula:

byte low_temp = Data[10] & 0x80;
if(low_temp)
{
temp = ( Data[10] * 16 + Data[11]/16) – 4096;
}
else
{
Data[10] = Data[10] *16;
Data[11] = Data[11] * 0.0625;
temp = Data[10] + Data[11];
}

To convert raw voltage into battery voltage you can use this formula

float battery = ((Data[4] * 256) + Data[5]);
float voltage = 0.00322 * battery;

 

 

LabView configuration utility for wireless Thermocouple Temperature sensor can be found here:

Wireless Thermocouple Sensor LabView Utility 

Please note the above utility will be used for testing and configuration.

 

See Also: How to Configure Wireless Sensors