A labeller can apply a label correctly in isolation yet still create stoppages when its signals, conveyor logic and restart behaviour are not agreed with the surrounding line. This guide sets out the information needed to define the control boundary before build and acceptance.
A labeller can apply a label correctly in isolation yet still create stoppages when its signals, conveyor logic and restart behaviour are not agreed with the surrounding line. This guide sets out the information needed to define the control boundary before build and acceptance.
Start by identifying which control system owns each part of the process. A stand-alone labeller may control only its own label head and short conveyor. An integrated cell may also control product spacing, top-hold belts, reject devices, inspection, guarding and downstream accumulation. The boundary should be shown on a simple line drawing so there is no uncertainty about who supplies the sensors, cables, isolators and software for each interface.
The control description should distinguish production commands from safety functions. A normal stop, line-ready signal or blocked condition is part of production control. Guard switches, emergency stops and safe isolation are safety matters that require a project-specific risk assessment and competent design. Do not assume that a production signal can perform a safety function.
List the signals exchanged with the upstream and downstream equipment in plain language before deciding the electrical format. Typical production states include available, ready, running, starved, blocked, faulted, changeover and maintenance. For each state, define the source, destination, normal condition, response time expected by the process and what the operator should see.
The most useful document is an interface schedule that pairs every signal with an agreed response. For example, a downstream-blocked state may stop the infeed while allowing the label currently in process to finish. An upstream-starved state may leave the labeller ready without generating a nuisance fault. This behaviour prevents product being trapped in an undefined state.
A labeller depends on repeatable product presentation. If containers arrive touching, at irregular gaps or with uncontrolled orientation, the label trigger cannot compensate for every variation. The line design should define where spacing is created, how much accumulation is permitted and which machine stops first when capacity is exhausted.
Product ownership is especially important where a stop can leave a pack between sensors. Record whether that product may continue, must be rejected or must be checked by an operator. The same principle applies to labels that have been printed but not applied: the control sequence should prevent an old or duplicated label being applied after restart.
Separate faults that require immediate stop from warnings that allow the current cycle to complete. Useful fault messages identify the device and condition rather than displaying a generic alarm. The recovery sequence should state whether the operator clears product, acknowledges the cause, returns guards and devices to their safe state, then performs a controlled restart sample.
Power loss and emergency-stop recovery deserve their own test. Confirm whether recipes, counters, print data and product tracking are retained, reset or reconciled. A restart should not create an unexpected label feed, product movement or stale print job.
The factory acceptance test should exercise the interface, not only normal running. Simulate starved and blocked conveyors, printer not ready, label end, product-sensor failure, inspection reject, guard opening and loss of a permitted production signal. Record the expected response and observed result for each test.
Repeat the most important tests after installation because conveyor lengths, upstream timing, site networks and operator procedures can change the behaviour. Keep the final signal schedule, electrical drawings, software backup and accepted restart sequence in the handover pack.
Provide a line layout, conveyor direction and height, the upstream and downstream machine descriptions, available control-system information, required data connections, preferred ownership of line start/stop and any existing reject or inspection equipment. Include a description of what should happen when the line is starved, blocked or restarted.
Lancing can then define the labelling-machine boundary and identify where further site-specific controls or safety engineering is required. Final control and safety arrangements must be confirmed for the actual installation.
Use the table as a project conversation starter. The final requirements and safe methods must be confirmed for the actual product, label, line and site.
| Area | Evidence to define | Acceptance focus |
|---|---|---|
| Line ready | Both connected systems are available for production | Agree whether absence prevents start or stops a running line |
| Starved | No product available from upstream | Avoid nuisance faults; remain ready where appropriate |
| Blocked | Downstream cannot accept product | Stop infeed in a controlled sequence and protect product tracking |
| Fault | A device or process condition needs intervention | Show a specific cause and define whether the current cycle completes |
| Data ready | The correct print or recipe data is available | Prevent application when data is missing, stale or not validated |
| Reject confirmation | A failed product has reached the reject destination | Decide whether failure to confirm stops the line or raises an alarm |
Use the most relevant guide for the next decision, then send the confirmed information with your enquiry.
Build a controlled response to jams, faults, power loss and interrupted labels.
AcceptanceTest normal running, fault states, handshakes and changeovers before despatch.
HandoverRetain interface schedules, drawings, backups and accepted settings.
EquipmentReview label-head integration with conveyors, sensors and controls.
Send the product, label, layout and operating information so the required machine, controls and project evidence can be defined before quotation.
Control questions should be answered in plain process language before they are converted into wiring, network messages or PLC logic.
Ownership should be assigned to the control system that can detect and safely manage the product through that zone. The agreed owner needs to know whether the product may continue, must stop, must be rejected or requires operator inspection after an interruption.
Show each transfer zone and sensor on the line layout so ownership does not change informally during commissioning.
The required signals depend on the line, but the schedule should normally describe availability, ready, running, starved, blocked, fault, data-ready and reject states where relevant. Each signal needs a defined source, destination and expected response.
Safety functions must be designed separately through the project risk assessment and must not be assumed from a production-ready signal.
The labeller should follow an agreed blocked sequence that protects product spacing and product-to-label tracking. It may finish the current application, inhibit new infeed and hold products in known positions rather than stopping every device at the same instant.
The correct sequence depends on available accumulation and whether a product can safely remain inside the application zone.
Recovery should identify products and labels left between tracking points, reconcile any printed-but-not-applied labels and prevent unexpected movement or application on reset. The operator needs a defined clearance or inspection sequence before automatic running resumes.
Test the sequence with products deliberately positioned at the difficult transfer points.
An encoder can provide a movement reference when label dispensing or application needs to follow actual conveyor travel rather than a fixed time delay. It is particularly useful where line speed changes during production.
The encoder source, mounting, resolution and behaviour during slip or stop must be matched to the application; fitting an encoder does not correct uncontrolled product movement.
Send the product, label and line details to Lancing so the answer can be checked against the real pack rather than treated as a generic machine assumption.
A blocked or starved signal is useful only when the conveyor length, product pitch and stop response support it. Continue with the labelling line layout and product flow guide to connect controls to physical capacity, inspection and reject positions.