Laboratory Temperature Kit

In the research laboratory chemical reactions are common to obtain results by combining two are more chemical compounds or solutions. Chemical reactions happen at a characteristic reaction rate at a given temperature and chemical concentration. Typically, reaction rates increase with increasing temperature because there is more thermal energy available to reach the activation energy necessary for breaking bonds between atoms. It is important to measure and maintain the exact thermal activation energy, which is needed to supply to complete the chemical process fruitfully. So we need a high resolution temperature sensor to measure thermal activation energy and transfer data to GUI or MCU kit to control and stabilize the thermal source at a particular temperature. “MAX31865 Evaluation Kit” is chosen as a high resolution temperature sensor kit for the present project to monitor and measure the reaction temperature because we can visualize timely data in GUI. This MAX31865 Evaluation Kit has the silent features so it can directly connect to the PC using mini-USB cable without interfacing to additional MCU. The temperature of source can be set to specific point to complete the reaction at exact activation thermal energy. This is how I am intended to use the MAX31865 Evaluation Kit in our research laboratory to monitor reaction temperature in a beaker or flask.

List of parts required for project are:
  1. MAX31865 Ev Kit.
  2. RTD temperature sensor with 1Kohms.
  3. Extension wire of length 2 meters.
The schematic diagram to record data from the sensor and convert it to digital data using on-board 16-bit ADC in max31865 chip.

Figure 1: Schematic diagram for RTD connected to MAX31865 chip.

Figure 2: Schematic diagram for SPI-to-USB converter circuit.

Procedure to install and connected hardware to GUI for MAX31865 Evaluation Kit:

The RTD sensor is connected to the MAX31865 Ev Kit, Follow the steps below to verify board operation:
1) Verify the two jumper wires (included) are properly secured in the terminal block in accordance with the 2-wire RTD Sensor Connector diagram on the PCB’s silkscreen.
2) Verify the 1kΩ resistor is properly secured in the terminal block connecting the RTDIN+ terminal to the RTDIN- terminal.
3) Set the EV kit hardware on a nonconductive surface that ensures that nothing on the PCB gets shorted to the workspace.
4) Prior to starting the GUI, connect the EV kit hardware to a PC using the supplied mini-USB cable, or equivalent. The POWER LED (D20) should be green and the COM LED (D21) should be red and slowly flash orange.
5) Windows should automatically begin installing the necessary device driver. The USB interface of the EV kit hardware is configured as a HID device and therefore does not require a unique/custom device driver. Once the driver installation is complete, a Windows message appears near the System Icon
menu indicating that the hardware is ready to use. Do not attempt to run the GUI prior to this message. If you try to run the GUI prior to this message, close the application and restart it once the driver installation is complete. On some versions of Windows, administrator privileges may be required to install the USB device.
6) Once the device driver installation is complete, visit to download the latest version of the EV kit software,
MAX31865EVKitSoftwareInstall.ZIP. Save the EV kit software to a temporary folder.
7) Open the .ZIP file and double click the .EXE file to run the installer. A message box stating “The publisher could not be verified. Are you sure you want to run this software?” may appear. If so, click Yes.
8) The installer GUI appears. Click Next and then Install. Once complete, click Close.
9) Go to Start >> All Programs. Look for the MAX31865EVKitSoftware folder and click on MAX31865EVKitSoftware.EXE inside the folder.
10) When the GUI appears, the text below the Maxim Integrated logo should indicate that the EV kit hardware is connected. The COM LED (D21) turns off and flashes red when communication occurs.

Figure: GUI for the MAX31865 Ev Kit to record and save the temperature data.

Source code for the MAX31865 chip to monitor and record temperature data:
* MAX31865 Evaluation Kit program for laboratory kit temperature monitor.
#include <SPI.h>
#include <MAX31865.h>
#define RTD_CS_PIN 10
MAX31865_RTD rtd( MAX31865_RTD::RTD_PT100, RTD_CS_PIN );
void setup()
Serial.begin( 115200 );
/* Initialize SPI communication. */
SPI.begin( );
SPI.setClockDivider( SPI_CLOCK_DIV16 );
SPI.setDataMode( SPI_MODE3 );
/* Allow the MAX31865 to warm up. */
delay( 100 );
rtd.configure( true, true, false, true, MAX31865_FAULT_DETECTION_NONE,
true, true, 0x0000, 0x7fff );
void loop()
rtd.read_all( );
if( rtd.status( ) == 0 )
double temperature = rtd.temperature( );
Serial.print( " T = ");
Serial.print( temperature, 1 );
Serial.println(" deg C" );
Serial.print( "RTD fault register: " );
Serial.print( rtd.status( ) );
Serial.print( ": " );
if( rtd.status( ) & MAX31865_FAULT_HIGH_THRESHOLD )
Serial.println( "RTD high threshold exceeded" );
else if( rtd.status( ) & MAX31865_FAULT_LOW_THRESHOLD )
Serial.println( "RTD low threshold exceeded" );
else if( rtd.status( ) & MAX31865_FAULT_REFIN )
Serial.println( "REFIN- > 0.85 x V_BIAS" );
else if( rtd.status( ) & MAX31865_FAULT_REFIN_FORCE )
Serial.println( "REFIN- < 0.85 x V_BIAS, FORCE- open" );
else if( rtd.status( ) & MAX31865_FAULT_RTDIN_FORCE )
Serial.println( "RTDIN- < 0.85 x V_BIAS, FORCE- open" );
else if( rtd.status( ) & MAX31865_FAULT_VOLTAGE )
Serial.println( "Overvoltage or Undervoltage fault occured");
Serial.println( "Fault exist; Please check connection" );
delay( 3000 );
Details of more source code can be cloned from the URL:

Initially connect the 2-wire RTD sensor to the RTD port by replacing the 1kohm resistor in the Evaluation Kit. Plug-in the USB cable to the PC and evaluation kit then open the GUI software which shows the EV kit hardware is connected. ON the conversion mode, VBIAS, set to 2-wire RTD connection if red bubble in fault status indicates their is open connection in the RTD sensor or in-appropriate sensor connected. If all is well then start to measure the data from the chosen environment. In the current project we are going to measure the Laboratory kit temperature i.e. magnetic stirrer temperature which is useful to make reaction rate faster. We placed the RTD temperature Sensor on stirrer pan to measure the temperature. The data recordings were saved in separate file to make calculation for the resulted solution.

Recorded data:

The video shows that the measurement carried out in our laboratory for measuring the magnetic stirrer pan temperature.

Improvement required for best utilization:
  1. If multiple recordings are observed on the same kit for two different processing it would me more advantage to the users and their is no need to used multiple MAX31865 kit.
  2. The data should be saved with different name before start of the process, in present state name is saved only after the process is stopped.
  3. If WiFi/ Bluetooth connectivity is available then it is easy for the user to utilize the kit for remote accessing the data from the measuring environment.
  4. An android app for smartphone will be a hand and helps to share the data and monitor in real-time.
The temperature of the magnetic stirrer pan is measure because it will transfer the heat to the solution so that the reaction rate will increase. Using MAX31865 Ev Kit we can exactly notice at which temperature the reaction rate is faster then we can optimism that conditions for the best results in our titration. The data is saved in separate file once the process is completed.
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