MCDL function is suitable for agricultural applications such as green houses or some places which have to keep high CO2 concentration level.
2. Why use MCDL
All gas sensors are subject to some sort of drift and the degree of drift is partially dependent on the use of quality components and good design. But even with good components and excellent design, a small amount of drift can still occur in the sensor that may ultimately result in the need for a sensor to be recalibrated. Sensor design and components have to do with drift. The primary contributor to sensor drift is the normal and unavoidable aging of the infrared light source within the sensor. The natural drift of the sensor is very gradual at a few ppm per month with the greatest drift occurring in the first few months of operation. Therefore, 10 minutes MCDL can be used when sensors show much different ppm in severe condition like as green houses and users also can do MCDL when they can't wait for ACDL logic period.
3. How MCDL works
There are some cautions to use MCDL.
Sensors should be located in the fresh air flowing circumstance near 400 ppm such as the room with windows opened or open places to outside before starting MCDL. It's because the recalibration done at 380~420 ppm gives best accuracy. and the 10 minutes Recalibration must be finished within 18~20 minutes. because MCDL will be restarted the recalibration again. Lastly, people should not exist during recalibration because even a breath of a person has 40,000 ppm CO2 which effect the accurate measurement.
There are two ways of MCDL.
First, users can do MCDL by giving 'Low signal' to MCDL pin. At that time, users have to be careful not to give 'Low signal' to ACDL and MCDL pin both. ('UART Command Guide' and ‘I2C programming guide’ could be provided by contacting Sales Rep.)
Second, users can do MCDL with TRB-100ST or EK-100 series which ELT SENSOR corp. has developed for users. TRB-100ST enable sensors to be tested and re-calibrated in field without R-T-V (Return to Vendor) process and EK-100 series enables even change or upgrade the MPU program of sensors on customer's side as needed.