Feature: T&M


and sharing it automatically with staff across a business, sometimes all that’s needed is a quick and easy way of taking a reading using a device such as a smartphone or a tablet. Tis is why Mantracourt developed the B24 Bluetooth strain transmitter. Te device uses Bluetooth 4.0 Low Energy (BLE 4.0), which is much more efficient for portable, battery- powered devices (tablets, smartphones, etc.). Te transmitter runs up to ten months on a pair of AA batteries and can easily be used with existing devices, since most phones and tablets already have Bluetooth built in. Te B24 is a small module that comes in


Measuring strain with


Bluetooth technology By Matt Nicholas, Product Design Manager, Mantracourt


T


he strain bridge measurement is found in a wide range of industrial sensors, typically load cells, to measure forces such as tension and compression,


or in other sensors such as pressure or torque transducers using Wheatstone bridge circuits. Before wireless technologies became popular,


whenever engineers needed to take a load-cell reading, they would (and many still do) rely on a physical connection to it. Tis would require the engineer to directly plug their hand terminal to the load cell into take a reading, or use a human-machine interface (HMI) to display the data from multiple sensors. Tat’s fine for a single load cell but, with


a few more units, the complexity begins to add up. Te cabling and installation of such a system can oſten end up being more than the load cells themselves, further adding time and effort.


Wireless options Te options for wireless transmission are varied, from low-power 2.4GHz devices, which can transmit on multiple channels and are remarkably tolerant of radio frequency interference, to devices that use mesh- or star-network topologies. Tese networks are more sophisticated and self-healing, and work at greater range than their non-mesh counterparts; however, this is at the expense of power, resolution and simplicity. Then there are the fully-fledged,


cloud-based IoT platforms, which may be an overkill if all that’s needed is periodic measurement of the load in a container as bulk material is decanted from it before being processed. This on- demand, session-based approach means the operator only takes a reading when needed, rather than being inundated with ongoing live feeds from the systems. While IoT platforms have their merits for accessing information remotely in real time


an IP67-rated enclosure, or as a board-only option to be integrated as required. Te transmitter is easily wired directly into the load cell using field terminals, and works with sensors across a range of sensitivities, from a few grams to a few hundred tonnes. Te result is a versatile transmitter for use anywhere there’s a load cell or strain bridge input, whether in automotive, industrial, agricultural or any other application – it has even been used on a sailing yacht to monitor strain in the rigging. One key feature that sets the B24 apart


from other Bluetooth transmitters is its multiple transmission capability. By harnessing the BLE functionality, multiple transmitters can send data to one device, and one transmitter can be viewed by multiple devices. Tese one-to-one, one- to-many, many-to-one and many-to-many functionalities greatly open up access to the data. However, the hardware technology is one


half of the story. Using a phone to take a reading is only valuable if the app offers the same kind of flexibility and customisation as a dedicated HMI or control system. To achieve this, there’s a specially-developed app for both iOS and Android features with customisable dashboards.


Implications Tese breakthroughs in Bluetooth technology and app customisation mean that engineers have more flexible options available to them, ranging from complete real-time IoT platforms to manual measurement, with Bluetooth offering a cost-effective option in between, proving that strain measurement need not be expensive.


www.electronicsworld.co.uk September 2021 29


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