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Self-build PLC-based counter helps control social distancing
Published:  14 May, 2020

The German PLC-maker Barth Elektronik has joined forces with RS Components to develop a simple self-build project to help implement social distancing.

Their People Counter can be built in less than an hour and records the number of people entering and leaving an area, indicating when it is safe to allow more to enter, while still maintaining the recommended safe distance from each other. It is aimed, in particular, at retail environments where safe social distancing can be difficult to control.

“The idea came from the challenge that many businesses currently face when restricting the number of people in shops,” explains Barth's CEO, Daniel Barth, who devised the project. “Maintaining a reasonable maximum can reduce the likelihood of the virus spreading further through human contact. It was important to find a precise, contactless solution that could protect public health, while avoiding the costs associated with employing extra staff to monitor numbers manually.”

The design is simple. Two photoelectric proximity sensors detect the direction in which people are moving, while a mini-PLC calculates how many are moving in and out of an area in real time. A password-protected CAN touchscreen is used to set the maximum number of people allowed in the area, and also acts as a “traffic light”, turning green when access is allowed and red when it is denied. There is also an audio alert.

The people counter is designed to enforce social distancing in buildings

“This is a simple project that could have a huge, positive impact on the way retailers help protect customers from Covid-19 while they are out shopping,” says RS’ vice-president of innovation, Mike Bray. “We would encourage any makers keen to help combat the virus to look at this project and consider how it could support businesses in their area, and then perhaps help those retailers to implement it.”

All of the parts can be bought from RS, and a bill of materials, 3D data, software and manuals can be downloaded from the RS DesignSpark Web site. A short video gives instructions on how to build the system.

An internal view of the people counter: it can be built in less than an hour