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People counter project for Covid-19

Miniature PLC manufacturer BARTH® Elektronik GmbH and RS Components have joined forces to bring you a maker project that will help people deal with the challenges of Covid-19, especially now that social distancing restrictions look like they are being eased. Essentially, it counts the number of people in a room and calculates whether any more people can enter that room. BARTH® Elektronik provided the idea and the necessary parts, which can be ordered from RS. 

The idea came from the challenge that many businesses are currently facing, of having to employ more supervisors to limit the number of people in shops to a reasonable maximum. This is to reduce the likelihood of the virus spreading further through human contact. Paying these extra staff increases the company's cost base. An alternative solution is to give out counting cards, but this raises further questions about hygiene. Solving this problem requires a precise, contactless solution that does not necessitate any additional staff.

Parts List

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The "PeopleCounter" maker project provides exactly this solution: The application counts the number of people entering and exiting a room, such as customers going in and out of a shop and compares this number with a value that has been pre-set on the device. When this value is reached, the red light switches on, or a sound is emitted, prohibiting more people from entering until others have left. It uses the same basic principle as counting the number of free spaces in a car park.

The PeopleCounter works as follows: Using two RS Pro, light barriers (729-5117) to detect the direction of movement, which enables the people entering the shop to be added and the people exiting it to be subtracted, thus allowing the number of people in the shop to be calculated in real-time.

The password-protected BARTH® CAN Display DMA-15 (174-5641) can be used to enter the maximum number of people. This display subsequently acts as a traffic light, turning green when access is granted and turning red when access is denied. A BARTH® miniature PLC (134-8863) processes the data and controls the display.

All the necessary parts are available from RS Components, please refer to the attached BOM for details. The application takes no longer than 30 to 60 minutes to assemble and is remarkably simple.

No other steps need to be taken. 3D data, manuals, BOM, and software are provided in Downloads below.

To commission the system, simply set up the device at the desired location and connect the mains adapter to the mains voltage. Then adjust and secure the mirrors for the light barriers and enter the maximum number of people on the display.

How-to video

As the next step, BARTH® Elektronik is thinking of introducing a fully preassembled product that is ready to install when delivered. The technology described above would be fitted in an easy-to-set-up configuration that indicates whether people are allowed to enter using two large "STOP" and "GO" traffic lights.

As an owner-managed company, BARTH® Elektronik GmbH is one of the leading supplier in the field of miniaturized PLC technology. Our focus is set on principles such as professionalism, tradition and long-term perspectives - personally and rooted in the soil - and represents the basis of the more than 25-year successful company history. Both the goal-oriented implementation of our mission and the continuous further development contribute significantly to the success of BARTH® Elektronik GmbH.

6 May 2020, 15:50


May 11, 2020 07:53

I think this requires a much larger beacon with Red and Green lights, something like the machine safety beacons.

I'd also add a big sounder to go off if someone enters when the sign is Red

May 11, 2020 07:53

@davecole red and green beacons can easily be connected to the mini-PLC - also a sounder which rings out if the maximum number of people is reached. A stele with two big square LED lights 'STOP' and 'GO' is currently under development.