HPM Series PM2.5 particle sensor


#1

Recently I was in a training with Honeywell on their HPMA115S0-XXX Particle Sensor. The Digi-Key part number is 480-7035-ND.

While here, Honeywell offered answers to some of their most frequently asked questions.

Q. What is the part number for a mating connector?

Q. What size particles does the HPM Series detect?

  • A. The HPM Series can detect particulates from 0.3 µm to 5 µm in size. The sensor uses the particle count data to provide a PM2.5 reading and a calculated PM10 reading.

Q. What particle distributions are the HPM Series calibrated against?

  • A. The HPM Series is calibrated to cigarette smoke, which most closely correlates to burnt fossil fuels or smog. The sensor can be calibrated to other particle distributions upon request.

It is important to understand which calibration is used if you are comparing sensors. If you were to put a sensor that is calibrated to cigarette smoke next to a sensor calibrated to Dust or Pollen they will have different readings.

Q. How accurate is the HPM Series?

  • A. Engineered for excellent accuracy, the HPM Series is able to detect particulate densities to within ±15% accuracy.

While this seems like a a poor accuracy we were informed that some competitive devices offer accuracy of ±30% or worse.

Q. Does the HPM Series use a laser or an LED to analyze media?

  • A. The HPM Series uses a laser-based sensing design which maximizes accuracy.

Q. What is the expected service life of the HPM Series?

  • A. With an expected service life of 20,000 hours, the HPM will operate for seven years when used for eight hours a day.

This is a running clock so just when operating the unit.

Q. How fast does the HPM Series analyze media and respond?

  • A. Ultra-fast, the HPM Series analyzes media in less than six seconds. This speed allows the HPM Series to quickly analyze and provide data to supporting equipment, allowing the device to respond to changing conditions in real-time.

It was suggested while we were in training to allow the unit to run for 15 seconds to ensure that you see a normalized result. The output of the sensor is a 10 second average.

Q Does orientation matter?

  • A Yes, they do have an installation orientation listed in the Data sheet. This is to ensure there is no buildup of particulate matter inside the housing. Here is a snip from the data sheet.

#2

I;ve worked with one of these sensors for around two months. Its behaviour is erratic and prone to hangups which drastically limit its usefulness. Admittedly it has a novel host, a BBC Micro:bit (an ARM/CORTEX) but that host interfaces correctly with other devices with the same serial interface.

Some of the problems are listed below:

  1. Demands power-up after the host CPU
  2. Power-up is followed by the transmission of garbage.
  3. Useful data was obtained only by switching-off autosend and restarting particle measurement
  4. The sensor performs several data read operations returnng sensible results but then unpredictably hangs, demanding power-up cycling. Most often it returns only one data set before hanging. Very occasionally it may return 50 or more data sets.
  5. A Honeywell engineer suggested a faulty power supply but checks show that that is not the problem: a clean, regulated 5.12V is placed across the sensor during operation (load potential) which consumes around 67mA.

I suspect a faulty sensor… Comments and advice welcome.


#3

When looking at your comments the power-up cycling is telling me there is an issue somewhere. The default setting on the unit should be to send information once powered. There should be no need to switch off the auto-send feature.

2.Power-up is followed by the transmission of garbage.

Though I have not set this unit up on my own I would not suspect this behavior to be out of the norm. It does take up to 6 seconds to get normalized data out of the sensor. In fact in training they suggested waiting up to 15 seconds before reading to ensure numbers have normalized as you are looking at a 10 second average.

If you have already talked with a Honeywell Engineer and they suggested a power supply I would have done the same and check as you have. Knowing this is not the issue you are probably to a point in your troubleshooting that it is time to try a different unit to see if it is a faulty unit or a coding issue. Since at times you are bringing back 50 sets of data and sometimes 1 I would also suspect that it is in the sensor.

-Robert


#4

Hello, I’m a bit late to reply but I vote for the faulty sensor too.
I can plug mine for hours and it still outputs results. It starts writing results on serial port as soon as it’s powered up and never hangs.

You should rule out any board/programming problem by connecting the sensor directly to a computer through a FTDI adapter and use a terminal application (for ex. RealTerm under windows).
Of course FTDI adapter should be set to 3.3V and only the main power lead to the sensor should be connected to 5V.