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T67xx CO2  

Sensor Module

OVERVIEW

The purpose of this document is to outline the required interface design and communication protocol for the 
T67xx CO

2

 Sensor modules. The intended audience is any developer who wishes to query the sensor for 

information utilizing either the I

2

C, PWM or UART interfaces.

All information about the performance of the sensor can be found on the Telaire website. Please refer to the 

spec sheets found at www.telaire.com for the latest specifications.

Amphenol

Advanced Sensors

®

Application Note

Summary of Contents for T67 Series

Page 1: ...odules The intended audience is any developer who wishes to query the sensor for information utilizing either the I2C PWM or UART interfaces All information about the performance of the sensor can be...

Page 2: ...mer 4 Safety While In Use 4 MATERIAL CONTENTS 5 INTERFACE CONNECTOR AND OPTIONS 5 UART 1 HZ PWM 6 I2C 25 KHZ PWM 7 PWM OUTPUTS 9 COMMUNICATION MODBUS PROTOCOL 12 UART RS232 RS485 12 I2C 12 I2C Timing...

Page 3: ...C will minimize the influence of heat on the measurement of the T67xx module The use of low temperature solder is also recommended It is recommended to handle the sensor by the edges of the PCBA Extr...

Page 4: ...o warranty representation or guarantee regarding the suitability of this product for any particular application including safety critical applications Nor does Telaire assume any liability arising out...

Page 5: ...The six pin through hole connector on the PCB is where power and IO for the sensor are located see Figure 1 below A four to six pin 0 1 2 54mm header is typically used to connect the sensor to a cont...

Page 6: ...this condition Table 1 I O Pin Configuration 1 Pin Description 1 UART TX output from sensor 2 UART Rx input to sensor 5 PWM output at approximately 1Hz Figure 2 Simplified Schematic I O configuration...

Page 7: ...plified Schematic I O configuration 2 In this condition the sensor implements an I2C interface The default conditions are The sensor only acts as a slave device I2C 7 bit addressing is used The defaul...

Page 8: ...or 5 Becomes a test input for Telaire and should be left unconnected by the user 6 Becomes an output pin used to control an RS485 transceiver Figure 4 Simplified Schematic I O Configuration 3 The cond...

Page 9: ...M output Typical value could be anywhere from 4 7 kOhm to 100 kOhm depending on chosen frequency of the PWM output and capacitance of the output load The slow 1Hz PWM output option supports legacy app...

Page 10: ...10 T67XX CO2 SENSOR MODULE Figure 6 Example of the PWM for 2K model...

Page 11: ...aditional PWM with 40 micro seconds period It can be can be filtered to create an analog output Below is one of possible circuit designs to convert 25 kHz PWM to an analog output where R3 and R4 will...

Page 12: ...lave In the examples below the implementer using the I2C interface will need to communicate with the sensor as either a master transmitter for Modbus requests or a master receiver for Modbus responses...

Page 13: ...O 138B H 5003 D uint16_t The current gas ppm calculation RESET DEVICE Coils WO 03E8 H 1000 D uint16_t Reset the sensor over the Modbus network START SINGLE POINT CAL Coils WO 03EC H 1004 D uint16_t St...

Page 14: ...01 H Number of registers to read LSB xx CRC LSB xx CRC MSB Modbus Response UART 15 H Slave Address default is 15 H 04 H Function Code 02 H Byte Count xx Status MSB xx Status LSB xx CRC LSB xx CRC MSB...

Page 15: ...Function Code 13 H Starting Address MSB 8A H Starting Address LSB 00 H Input registers to read MSB 01 H Input registers to read LSB xx CRC LSB xx CRC MSB Modbus Response UART 15 H Slave Address defaul...

Page 16: ...arm up mode xxx1xxxx xxxxxxxx 1000 H NA xx1xxxxx xxxxxxxx 2000 H NA x1xxxxxx xxxxxxxx 4000 H NA 1xxxxxxx xxxxxxxx 8000 H Single point calibration For error conditions a 1 indicates an error a 0 indica...

Page 17: ...MSB Modbus Response UART 15 H Slave Address default is 15 H 04 H Function Code 02 H Byte Count xx MSB of the 16 bit gas ppm data xx LSB of the 16 bit gas ppm data xx CRC LSB xx CRC MSB Example 6 Modbu...

Page 18: ...le Coil function 5 and write 00FF H to the register at the address 03E8 H 1000 D to reset the sensor Example 8 Modbus request to reset the sensor UART Modbus Request UART 15 H Slave Address default is...

Page 19: ...tion bit is set The calibration can be stopped before completing See examples Use the Modbus Write Single Coil function 5 and write 00FF H to the register at the address 03EC H 1004 D to start the cal...

Page 20: ...ut Value MSB 00 H Output Value LSB The calibration command cannot be restarted but can be stopped as detailed in the following example Example 12 Modbus request response to stop Single Point Calibrati...

Page 21: ...or power cycled The change does not take effect immediately Use the Modbus Write Single Register function 6 and write the new address to the register at address 4005 D 0FA5 H Example 14 Changing the...

Page 22: ...NABLE DISABLE ABC Logic is manipulated through the Modbus interface by using the Write Single Coil function 5 Coils are viewed as basically switches relays or discrete i e single bit inputs and output...

Page 23: ...not return to normal mode until the same register 100B H is set to 1 The command for this is 0x15 06 10 0B 00 01 CRC After that the RAM entry needs to be written to flash memory The command is 0x15 05...

Page 24: ...H Function Code 10 H Register Address MSB 0B H Register Address LSB 00 H Register Value MSB 00 H Register Value LSB xx CRC LSB xx CRC MSB Example 19 Flash Update UART Modbus Request UART 15 H Slave Ad...

Page 25: ...s 15 H 05 H Function Code 03 H Register Address MSB E8 H Register Address LSB FF H Register Value MSB 00 H Register Value LSB xx CRC LSB xx CRC MSB Example 21 Sensor Takes Single Measurement UART Modb...

Page 26: ...2 H Byte Count 01 H MSB of the 16 bit data 9F H LSB of the 16 bit data xx CRC LSB xx CRC MSB MEASURE ON DEMAND MODE USING I2C The default T67xx I2C slave address is 15 H and not shown Example 23 Enabl...

Page 27: ...I2C Modbus Request I2C 05 H Function Code 03 H Register Address MSB E8 H Register Address LSB FF H Register Value MSB MSB to Reboot sensor 00 H Register Value LSB LSB will always be zero Modbus Respon...

Page 28: ...on R15 15 second timing models Step Byte Sequence CRC excluded Reply CRC excluded Purpose Read Sensor Mode 0x15 03 10 0B 00 00 15 3f 80 Normal Mode Read current sensor mode If response is 15 00 00 fol...

Page 29: ...registers MSB 0x01 number of registers LSB 0x46 CRC LSB 0x70 CRC MSB static uint16_t Read_CO2_Cmd_Length uint16_t sizeof Read_CO2_Cmd sizeof uint8_t The following example sends the above character ar...

Page 30: ...write 0x8B Wire write 0x00 Wire write 0x01 end transmission Wire endTransmission read report of current gas measurement in ppm after delay delay readDelay Wire requestFrom ADDR_6700 4 request 4 bytes...

Page 31: ...00 Wire write 0x01 end transmission Wire endTransmission read report of current gas measurement in ppm delay readDelay delay in mS Wire requestFrom ADDR_6700 4 request 4 bytes from slave device data 0...

Page 32: ...l Corporation All Rights Reserved Specifications are subject to change without notice Other company names and product names used in this document are the registered trademarks or trademarks of their r...

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