Contrinex’s Smart Photoelectric sensors offer additional benefits in the Smart factory, beyond their primary purpose – Here we look at their roles of over and under-height detection, or output monitoring, and see what additional functionality they provide a Smart manufacturing cell.
The flexibility of a smart manufacturing cell introduces challenges and risks from the large variety of work it undertakes in small production batches when compared to stable, de-bugged, volume production. Therefore, to prevent issues such as over-size parts causing problems at subsequent manufacturing operations, sensors are used to check incoming parts are of a size that subsequent processes can handle.
The IO-Link connectivity of Contrinex’s photoelectric sensors enables these height thresholds to be adjusted specifically for each production batch to also provide some verification of the part.

Three photoelectric sensors are used in different locations, two for height checking and the third for counting cartons as they leave a shrink-wrapping station on the way to be readied for despatch.
The first sensor is a Diffuse photoelectric sensor mounted above the output conveyor of the PCB reflow oven. It checks the height of assembled PCB modules, where the PCB assembly area, inputs into this manufacturing cell – If a PCB is under or over height, the sensor will trigger an intervention, pausing the outfeed conveyor positioned beyond the oven and also notifying the PCB production area.

The flexibility of a multipurpose Smart manufacturing cell is enhanced if it includes similarly flexible packing and shipping capabilities. Therefore, within the cell, finished parts are packed by a small robot into cardboard cartons which are heat-shrink wrapped and stacked onto an Automated Guided Vehicle (AGV), which takes them to a finished goods storage area.

Smart photoelectric sensors are located, immediately after the shrink-wrapping oven. A pair of Through-beam sensors monitor carton throughput for stock-control purposes and report via IO-Link to a central server. A Diffuse sensor mounted above the conveyor checks that the cartons are not taller than expected, for example, if the carton was incorrectly closed or sealed.


Contrinex’s small, cubic ‘C23’ (20 x 30 x 10mm) photoelectric, Digital distance-Measurement smart Sensors (DMS) were selected because they provide industry-leading performance. They offer best-in-class sensing distances across a wide choice of detection technologies: Background suppression, 0 to 300mm, Diffuse, 0 to 1.5m, Reflex, 0 to 8m, Through-beam, 0 to 30m.

Being part of a large family of ‘C23’ photoelectric sensors, they also have custom-designed, low-cost, multi-position, stainless-steel, mounting brackets and protective sleeves to help quickly position the sensors.

The Smart functionality of the DMS photoelectric sensor which monitors the PCB reflow oven is used to log the cumulative number of PCBs – It sends an SIO signal directly to the PLC when a pre-set quantity is completed, in turn triggering an upload of a new sensor configuration via IO-Link.

At the heat-shrink oven, the Smart Through-beam photoelectric sensors that monitor throughput, also initiate an energy-saving function. If a pre-set period elapses without a carton being detected, the sensor sends a high-speed SIO signal to a local machine controller for the next process in the cell, placing it into a standby condition that reduces energy consumption.

The Diffuse sensor which checks for over-height conditions after the shrink-wrapper, not only prevents problems at the automated handling system which stacks the cartons onto the AGV, but it also maintains a count of throughput. When a pre-set quantity of cartons is reached it sends a trigger to alert the finished goods warehouse that the AGV will leave shortly and that a new AGV should be dispatched to that manufacturing cell. It also triggers an upload of the consolidated manufacturing data for all of the cartons loaded upon the soon-to-be departing AGV.

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