The smart gateway receives data from Pressac sensors, formats it appropriately, and hands it over to the management software, on premises or in the cloud.
But what does the gateway do, and why is it even necessary? Why can’t the sensors talk to the software themselves?
Pressac sensors are largely battery powered, or powered by harvesting small amounts of energy from the environment. The battery-powered sensors are small, lightweight, and last for multiple years. That means that our sensors have to operate on low power.
We want our sensors to communicated wirelessly, because wired communication would be a massive infrastructure undertaking on many sites, having to run data cables to every point at which you want to measure would likely become economically unfeasible. And we don’t want to have to drill holes and make changes to a site – for ideal retrofitting, everything should be easy to retrofit.
Connect a phone to a WiFi network and make a battery that lasts 3 years. That battery isn’t going to fit in your pocket! This is because WiFi is a protocol which prioritises range and bandwidth over energy efficiency. Even when a WiFi device is idle, it is constantly communicating with the wireless network, just to make sure that its still there.
This is known as a “handshake,” and it has many advantages when handling complex data, but these constant communications use a lot of power.
That’s why we use a protocol called EnOcean – this is an extremely low power, low bandwidth wireless protocol, which allows the sensors to operate on harvested energy, or on battery power for many years.
This separation of sensors and Gateways has other advantages. It means that the sensors don’t need to know what time it is (running a clock on the sensor would use more power!), and can simply send out a small and simple data packet, leaving the Gateway to do the rest of the work. This keeps installations simpler, as there is often no configuration of the sensors required at all.
A change in a naming convention, or a change in the connection details for the software component, means that only Gateways need to be reconfigured, not individual sensors.
So, what does the Gateway do?
Well, it is well-named! The gateway’s job is to receive these tiny pieces of raw data from the sensors, translate it in to a more useful form of information, and pass it on to the next step in the chain.
This means that a wide variety of sensors can communicate with a software or management suite, using consistent and widely used protocols and methods, such as JSON formatted data sent over MQTT (two widely used standards within the IOT world).
What is the difference between a gateway and sensor?
The gateways, unlike the sensors, are mains powered, and networked. That means we don’t have to worry about how hard the gateway is working, or worry quite so much about the data size.
The gateway can take a simple numerical input, and output something with a timestamp, location and various other factors appended.
It also means that the Gateway can handle the secure communication with the cloud, using technology such as TLS, which would be too data-intensive for the sensors themselves to handle.
How do sensors benefit from being connected to a smart gateway?
The gateway allows our sensors to stay small, scalable and secure, easy and unintrusive to install, easy to configure and make use of, and ultimately to create a standalone solution requiring very little maintenance over a long period of time.
Without splitting the sensors and gateway functions in this way, this ideal process of getting data from sensors in to the software system would be impossible to achieve within the constraints which keep our sensors ideally placed for your building.
Chris Green
A customer-facing Technical Support Engineer, passionate about delivering innovative solutions to complex problems through the use of IoT. With nearly two decades of experience in the electronics industry, Chris has developed a customer-first approach and his product expertise, combined with his sense of humour makes him a well-respected authority on intelligent workplaces.
