Contrinex photoelectric sensors keeps container handling on track

In high-throughput logistics environments, every second counts. For operators of straddle carriers at a busy container port, the ability to identify container configurations accurately and automatically has become a critical factor in improving efficiency, reducing operator workload, and maximising yard capacity.

Straddle carriers are the workhorses of modern container terminals, operating continuously to transport, load and stack shipping containers. During each lift, a carrier's spreader beam may engage either a single 40-foot container or a pair of 20-foot containers positioned together.

Correctly identifying the container arrangement is essential. Storage locations, vehicle routing and yard space allocation all depend on accurate data being passed to the terminal management system. Historically, drivers were required to verify container configurations manually, introducing the possibility of delays and human error.

To automate the process, the port operator initially installed mechanical sensing devices. However, the demanding operating environment quickly exposed their weaknesses. Continuous vibration, shock loading and exposure to the harsh coastal atmosphere caused the sensors to drift out of calibration, requiring frequent adjustment. Despite vehicle maintenance intervals extending to around 1,000 operating hours, sensor recalibration was often needed every few days.

The port operator required a more robust and maintenance-free solution capable of delivering dependable performance around the clock.

Compact photoelectric sensors with background suppression

The chosen solution utilised Contrinex C23PA photoelectric sensors mounted centrally on each lifting beam. Two pairs of background suppression sensors are positioned strategically to identify container configurations as the spreader beam descends. One sensor in each pair detects the presence or absence of corner castings at the central lifting points, while the second sensor checks for the gap that exists between two adjacent 20-foot containers.

This dual-verification approach provides a highly reliable method of distinguishing between a single 40-foot container and two 20-foot units, while also minimising the possibility of false detections.

The compact dimensions of the sensors, combined with long sensing distances, allow them to be mounted safely away from potential impact zones. Their rugged construction and vacuum-encapsulated electronics provide exceptional resistance to vibration, a critical requirement on constantly moving container-handling equipment.

Built for the port environment.

Container terminals present one of the most challenging environments for industrial automation equipment. Salt-laden air, moisture, temperature fluctuations and constant mechanical stresses can significantly shorten component life.

The C23PA sensors address these challenges through a robust moulded ABS housing with an IP67 protection rating. Sealed sensing faces and durable cable or connector options ensure long-term reliability, while integrated M12 or M8 connection solutions simplify replacement during routine servicing.

As a result, the port operator has reported a significant reduction in maintenance requirements and the complete elimination of the calibration issues that plagued the previous mechanical sensing system.

Supporting digitalisation through IO-Link

Beyond reliable detection, the C23PA sensors support IO-Link communication across all PNP variants, enabling seamless integration with modern automation architectures.

For operators managing large fleets of container-handling vehicles, IO-Link offers valuable advantages including remote diagnostics, rapid sensor replacement, parameter backup and centralised monitoring. Sensor settings can be restored automatically following maintenance, reducing commissioning time and helping maximise equipment availability.

These capabilities align closely with Industry 4.0 initiatives, where connected devices provide enhanced visibility and support predictive maintenance strategies.

Despite measuring just 30 x 20 x 10 mm, the C23PA family delivers impressive sensing performance across a wide range of applications. Variants are available for diffuse, background suppression, retro-reflex, through-beam and transparent object detection tasks.

Proven results in continuous operation

For the container port operator, the results have been clear. Automatic container identification has removed the need for manual verification, improved operational efficiency and enhanced the accuracy of container handling processes.

Most importantly, the move from mechanically actuated sensors to robust photoelectric technology has delivered a stable, long-term solution capable of withstanding the extreme demands of 24/7 port operations.

As businesses continue to seek greater productivity through automation and digitalisation, robust sensing technologies such as the Contrinex C23PA series are proving that even small components can have a significant impact on operational performance.