An unscanned pallet rarely gets noticed right away. In the system, it is not recorded where it actually sits, and the difference often only shows up weeks later, when a customer order can't be picked or the annual inventory has to correct stock levels. The cause is usually simple: under time pressure, the handheld scan of a pallet gets skipped. A scan tower addresses exactly this. It captures all the codes on a pallet automatically while the forklift drives past the tower. This article explains how a scan tower works, which criteria matter in the design, and how to get from a pilot tower to a full rollout.
Key Takeaways
- Handheld scans skipped under time pressure leave pallets unrecorded. The gaps often don't surface until the annual inventory, and they disrupt shipping, inventory planning, and promises to customers.
- A scan tower uses several fixed-mount, camera-based SR-5000 Series code readers to capture all pallet codes on both sides and in both directions of travel, without the forklift stopping.
- Because a pallet carries many codes, plus codes on the forklift, filtering by code type and content prefix processes only the relevant load ID and avoids double bookings.
- Labels can sit anywhere on pallets up to about 10 feet tall and about 4 to 8 feet wide, so field of view and the number of readers per side have to be designed for the worst case.
- If forklift ID and load ID are linked in the same pass-through event, you get complete traceability from receiving to loading.
The Hidden Cost of Unscanned Pallets
Manually scanning every single pallet is a process risk. It depends on the driver's care and available time, and both vary in day-to-day operations.
- Inventory discrepancies. When a scan is skipped, system stock and actual stock drift apart. Those differences affect shipping, inventory planning, and the commitments you make to customers.
- Late discovery. Missing bookings often don't show up until the annual inventory. By then, the cause is hard to reconstruct, and the correction costs twice as much.
- Every handheld scan is a risk. As long as capture depends on a manual step, the risk remains. That is why automation starts right at the drive-through, where responsibility for the pallet changes hands anyway.
The damage is not limited to the one missing booking. An unscanned pallet distorts the availability calculation: the system treats goods as reserved or free when they are not. That leads to bad planning decisions, unnecessary reorders, and, in the worst case, customer commitments you can't fill. Because the error is small and invisible at the source, it gets more expensive the later it is found.
How a Scan Tower Works
A scan tower consists of several fixed-mount, camera-based code readers that cover the drive-through area. In one application at a receiving dock, a scan tower with SR-5000 Series code readers captures the pallet codes automatically as a pallet jack or forklift drives past, without the driver having to get off or stop.
- Two-sided capture. Because the label can be on either of two sides of the pallet, readers are mounted on one or both sides so that the left and right sides are covered. Batch reading of stacked pallets is also possible.
- Both directions of travel. A well-designed tower captures in both directions, so loads going in and out are booked equally. The distance between the forklift and the tower should be defined and kept, based on project experience.
- Mirrors for tight spaces. For difficult installation situations, the SR-5000 Series offers accessories such as connection boxes, mirrors, and mounting brackets that make it possible to cover even tight tower geometries.
Many Codes Per Pallet, and Only the Right Ones Count
In the drive-through area, a pallet often carries far more codes than the one relevant load ID. In documented projects, there are twelve codes on the left and right sides of the pallet, plus codes on the forklift itself, such as ITF and DataMatrix. A scan tower therefore has to do more than read. It has to select:
- Filtering by code type and content. Only the desired codes are processed, for example by symbology or by a defined content prefix. That way, stray and secondary codes never reach the booking. Filtering is a common code reader function, and the exact setup is device-specific.
- Avoiding duplicate reads. In the tower area, where several readers see the same pallet, the same pallet ID has to be assigned clearly to a single drive-through event, so multiple reads don't lead to double bookings.
This selection is critical. A tower that "reads everything" produces data noise. A tower that reads the right codes on purpose produces clean bookings. The quality of a scan tower is therefore measured not just by its read rate but also by how reliably it can pick the one correct code out of many.
Plan the filter logic early with whoever is responsible for your WMS. Which symbology and which content prefix identify the relevant load ID is a business decision that should be settled before commissioning. Otherwise, the tower will read correctly from a technical standpoint but pass the wrong codes, or too many codes, to the system.
Design Factors
Whether a scan tower works reliably day to day is decided in the design. The following constraints come from real projects and should be clarified early:
- Pallet height and width. Labels can sit anywhere on pallets up to about 10 feet tall and about 4 to 8 feet wide, which is an application constraint. Depending on the model, the SR-5000 Series supports reading distances up to about 10 feet or up to about 13 feet, so it can be mounted at a good distance from the drive-through. Field-of-view height and the number of readers per side follow from the maximum pallet height. The specific field-of-view values are based on project experience.
- Free label position. Because the label can be anywhere on the pallet, the combined field of view of the readers has to cover the entire side, not just an expected zone.
- Reading through film. SSCC labels often sit under one or two layers of stretch film, which is a common real-world condition. Confirm this in a pretest with wrapped original pallets. In documented applications, reflective packaging film is not a fundamental obstacle.
- Tower geometry. Drive-through width, field-of-view height, and mounting points have to fit the building. Early coordination between logistics, facilities, and system design pays off here.
- Driving speed and distance. How fast the forklift drives through and how far it stays from the tower affect read reliability. A defined drive-through routine that can realistically be followed in operation is part of the design, not something to add later in driver training.
Rule of thumb for the design: always evaluate the worst case, not the normal case. The lowest label position on the tallest pallet, the most heavily wrapped example, and the fastest realistic drive-through together decide whether the tower stays reliable day to day. A tower that only reads under ideal conditions just moves the skipped-booking problem from the handheld scan to the technology.
Linking Forklift ID and Load ID
A scan tower can do more than book the pallet. Because codes on the vehicle are also in the field of view during the same drive-through event, forklift ID and load ID can be linked:
- Who moved which pallet? Codes on the vehicle identify the forklift, and the labels identify the load, captured in a single drive-through event. That gives you a complete record of who moved which pallet, when, and through which tower.
- A basis for load verification. This link is the foundation for reliable load verification and for proof to customers, such as which pallet was loaded onto which route.
From Pilot Tower to Rollout
A scan tower is a system-level investment and should be introduced as one, step by step rather than everywhere at once:
- Pilot tower at the most critical dock. Start at the tower where the most bookings are lost today. Measure read rate and process acceptance there under real conditions. KEYENCE can help you evaluate this with an on-site demonstration on your own pallets.
- Scale to all towers. After a successful pilot, you can roll the concept out. Real projects can include up to 19 loading stations, a scale that stays manageable only with a standardized tower configuration.
- Standardization lowers effort. A consistent configuration per tower lowers both the rollout effort and later maintenance, and keeps the system maintainable for years.
Conclusion
A scan tower fixes a problem that is often invisible in day-to-day operations but gets expensive later: skipped pallet bookings. By capturing all relevant codes automatically as the forklift drives through, it removes the manual scan as a source of error. Success depends on capturing label positions on both sides, filtering codes cleanly, running a realistic pretest with film, and rolling out tower by tower from the pilot to the last loading point. If forklift ID and load ID are linked as well, you get complete traceability from receiving to loading. For more on this topic, see KEYENCE's logistics solutions and its guide to barcode scanner integration.
Frequently Asked Questions
Several fixed-mount, camera-based code readers monitor the drive-through area. In one application, a scan tower with SR-5000 Series code readers captures the pallet codes automatically as a pallet jack or forklift drives past, without the driver getting off or stopping.
In the tower area, a pallet often carries more codes than the one relevant load ID, plus codes on the forklift itself. Filtering by code type or content prefix processes only the codes you want, so stray and secondary codes don't reach the booking and double bookings don't occur.
Reflective packaging film is generally not an insurmountable problem for camera-based code readers. Because SSCC labels often sit under one or two layers in practice, you should test this condition in a pretest with fully wrapped original pallets. What matters is not the layers themselves but the reflections from the film, which can be the real source of trouble.
In real projects, labels can sit anywhere on pallets up to about 10 feet tall and about 4 to 8 feet wide. Depending on the version, the SR-5000 Series supports reading distances up to about 10 feet or up to about 13 feet. Field-of-view height and the number of code readers per side are designed around the maximum pallet height.
Yes. Because vehicle codes are also in the field of view during the same drive-through event, forklift ID and load ID can be linked clearly. That makes it possible to trace who moved which pallet, when, and through which tower. This information is the basis for load verification and customer proof.
- Logistics Code Reader SR-5000 series
Logistics Code Reader
SR-5000 series
