LoRa® ERS Desk

ERS Desk is a LoRaWAN sensor for measuring desk occupancy. ERS Desk is designed to mount under the desk and senses when somebody is using the desk (standing/sitting).It can be used for dynamic workplace management, facility management and workplace statistics. The sensor also measures temperature humidity and light. ERS Desk is powered by two 3,6V AA lithium battery. The Battery life is estimated to be up to 5 years but depends on sample interval, transmit interval, data rate and environmental factors. You are welcome to use our online battery lifetime calculator. All Elsys sensors are equipped with NFC (Near Field Communication) for easy configuration with an Android phone. With our application “Sensor Settings“, you can change sample rate, data rate, encryption keys, triggers, activation and much more. All parameters can also be changed over the air from the server.  All our sensors are built on the LoRaWAN stack from Semtech. Channel planes for US902-928, EU863-870, AS923, AU915-928, KR920-923

Specifications ERS Desk

  • LoRa Alliance Certified
  • Temperature
  • Humidity
  • Light
  • Occupancy (body sense)
  • NFC for easy configuration
  • Over the air configuration
  • Size : 86x86x26mm
  • Accuracy: ± 0.5°C, ±2%rh
  • Resolution: 0.1°C, 0.1%rh
  • Approx. range: 8km*
  • Battery life: 5 years**
  • US902-928, EU863-870, AS923, AU915-928, KR920-923
  • 2 x 3.6V AA lithium battery

* LoRa™ modulation SF10
** Depending on interval

 

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Installation

 


3D model

Sensor application

Sensor startup

sensor_startupWhen the sensor starts up it loads configuration from the internal memory  and merge it with user configuration. When the configuration is done the sensor writes the new configuration to the NFC chip. The sensor always writes new configurations to the NFC chip when something changes in the sensor or if NFC data is corrupted by a NFC writer or phone. The sensor always writes new configuration to NFC chip at startup. When configuration is done the sensor tries to join the network if OTAA (Over The Air Activation) is enabled.The sensor led flashes orange  when it tries to join a network. The sensor tries to join the network every 10 second and increases the join timer at every failed attempt by 10%,  up to maximum 1 hour. After startup,configuration and join the sensor enters sampling mode.

 


NFC read/write

When reading or writing NFC data to the sensor it starts a timer and delays its action x seconds. It delays its action because of the bad connection that can be in NFC communication. Types of bad connection can be distance, location or rapid movement. After the delay the sensor determines if the NFC data has changed or not. If the data has change the sensor reboots and starts from power up. When writing data to the sensor try to get the best connectivity as possibly. Locate the NFC antenna of the phone and sensor. Keep the 2 devices as close as possibly and don’t move them while writing or reading. When you have written data to the sensor, let the sensor reboot and restart before trying to write again. You can always validate your settings by reading the NFC data after the sensor has restarted.

sensor_nfc


Sampling mode

sampling-mode


Battery life calculator

Chose sensor (ERS,ELT-1, ESM5k) and data coding(SF7-SF12).  Fill in number of samples per hour. Use “All sensors” field to change all time settings at once.

*Receive window2 (SF9) depends on server settings .

** Battery life is a theoretical value. Battery life is negatively affected by moister, high temperature, dirt, vibration and more. Most battery manufacturer grantees maximum 10 years of battery life (storage and usage).