Introducing our new LoRaWAN® compatible sensor node called EM-ELST01
In this article, we will introduce our first LoRaWAN® sensor node, EM-ELST01, which can reliably capture structural state changes in harsh environments.
(Follow this link to our device brochure in English. 日本語版はこちら)
EM-ELST01 was released in November 2022. And we officially presented it to the Japanese public at the EdgeTech+ exhibit, where we shared a stand with TTN Japan in the LoRa Pavilion. The device is available through our online shop (Japanese only). For international customers interested in our device, please get in touch with us through our contact form or our Facebook page.
Device Overview
The focus of this device is reliability, durability, and simplicity. The reliability is achieved through the redundant measurement of structural changes by the installed accelerometer and open/close switch sensor. The high reliability for capturing state changes makes this device even suitable for monitoring critical infrastructure.
Further EM-ELST01 comes in a dust-/waterproof casing (equivalent to IP66) and with a large capacity battery. This gives the device the durability to be long-term installed in harsh environments such as near the seashore or on construction sites.
Besides the accelerometer and switch sensor this device features only a temperature sensor and LoRa® antenna. By keeping a simple design this device is so cost-efficient that it can be used for prototyping as well as for large-scale deployments.
So far, this device was used for proof-of-concept projects such as:
- Monitoring floodgates along the coastline. Allowing local government officials to check remotely if the gates are open or closed on regular checks and in case of disasters such as typhoons or tsunamis.
- Monitoring the activity of construction site vehicles, to improve site management and security.
Technical Specifications
From here we will introduce the basic technical specifications since our current device manual is only available in Japanese.
Firmware
The specifications and code for the firmware of EM-ELST01 were produced by ourselves. The device supports LoRaWAN® v1.0.3 Class A and facilitates connection to TheThingsStack v3. The default firmware is optimized for general energy efficiency. But on customer request, we can also supply devices with customized uplink formats according to their requirements.
The default uplink format consists of one periodic (F1) and two event-triggered (F2, F3) payload formats. As shown in figure the figure above the largest payload is transmitted by the periodic uplink. The time between the periodic uplinks (F1) can be adjusted through downlinks or AT commands. The F2 uplink is sent every time the switch sensor registers a change. But the F3 uplink is only sent for the first event between two periodic uplinks, see figure below. The threshold value for detecting motion from the accelerometer can also be adjusted through downlink or AT commands.
Hardware
EL-EMST01 comes in two different versions, one has an internal switch and the other an external switch sensor, see figure below.
The accelerometer utilized in this device is ADXL335 which has a minimum measurement range of +- 3g. Though this accelerometer might not be good enough to precisely monitor earthquakes, for example, it is more than sufficient to register structural state changes. (A nice introduction on how to select accelerometers can be found here.)
The device also features the low-cost temperature sensor DS18B20, allowing the user to better monitor the device’s conditions. It should also be noted the EM-ELST01 uses 4000mALi/SOCl2 batteries. Their high capacity allows continuous use of the devices for years, but these batteries are normally not sold at retailers.
For inquiries or further questions please do not hesitate to contact us.