What causes fault code CONV-ACCUM1 (Accumulation Conveyor — Zone Full / Back Pressure)?

Downstream equipment stopped or faulted — discharge point not accepting product. Sortation diverter failed — product not being diverted, accumulating on main line. Product spacing too tight — gaps closing up causing premature zone full signals. Zone photo-eye misaligned — seeing product when zone is empty (false full). Zone release timing incorrect — zones not releasing product in proper sequence

How do I fix fault code CONV-ACCUM1?

Check downstream equipment status — clear any faults or jams at the discharge end. Verify all zone photo-eyes are clean and aligned — test each zone by manually blocking and unblocking. Check product spacing at infeed — if products are touching, the singulator or gap-maker is not working. Verify zone control logic — zones should release in slug mode or singulation mode per application. If one zone is falsely showing full, check that specific photo-eye alignment and sensitivity. Check that sleep/wake function (if equipped) is working — zones should go to sleep when no product is present for energy saving

Accumulation Conveyor — Zone Full / Back Pressure

CONV-ACCUM1

Accumulation conveyor has all zones occupied. Back pressure detected. Upstream conveyors should stop feeding product until space opens.

low conveyor

conveyor accumulation zone back pressure photo-eye flow control

Probable Causes (ranked)

Downstream equipment stopped or faulted — discharge point not accepting product
Sortation diverter failed — product not being diverted, accumulating on main line
Product spacing too tight — gaps closing up causing premature zone full signals
Zone photo-eye misaligned — seeing product when zone is empty (false full)
Zone release timing incorrect — zones not releasing product in proper sequence

Fix Steps

1 Check downstream equipment status — clear any faults or jams at the discharge end
2 Verify all zone photo-eyes are clean and aligned — test each zone by manually blocking and unblocking
3 Check product spacing at infeed — if products are touching, the singulator or gap-maker is not working
4 Verify zone control logic — zones should release in slug mode or singulation mode per application
5 If one zone is falsely showing full, check that specific photo-eye alignment and sensitivity
6 Check that sleep/wake function (if equipped) is working — zones should go to sleep when no product is present for energy saving

Field Trick

When an accumulation conveyor has all zones showing full but you can see empty zones, the problem is almost always a single dirty photo-eye. One blocked sensor tells the upstream zones 'I'm full' and the whole line backs up. Clean photo-eyes from the discharge end back toward the infeed to find the culprit.

Suggested Replacement Parts

Parts matched to fault category: Photoelectric Sensor

Banner QS18VP6D Photoelectric Sensor P/N: QS18VP6D Diffuse mode, 18mm barrel, 100mm range, PNP

AutomationDirect $65.00 Amazon $72.00 Grainger $85.00

IFM Efector O5D100 Photoelectric Sensor P/N: O5D100 Diffuse reflection, M18, 50-1000mm range, IO-Link

AutomationDirect $85.00 Amazon $95.00 Digikey $90.00

Prices are estimates. Verify part numbers match your equipment before ordering.

Need a deeper diagnosis with photo analysis and AI-powered troubleshooting?

Run Full Diagnosis