Scanning where Wi-Fi is weak: offline collection and later upload

Metal racks reflect and absorb radio signals, thick concrete walls stop them, and a cold store or a basement may have no signal at all. A device that needs a live Wi-Fi connection to accept each scan will stall, repeat or lose readings in such places. A reliable count does not depend on the network: scans are stored on the device first and sent later in controlled batches, and the team checks that nothing was lost on the way.

Store first, send later

• Use devices that save every scan in their own memory at the moment of reading, whether or not they are connected, such as mobile terminals.
• Test before the count. In the corner with the weakest signal, switch Wi-Fi off, scan 20 items, switch it on and confirm that all 20 arrive.
• Check that the device is set to hold the data and retry when it cannot connect, not to discard it.
• Check that all devices show the same date and time, because the merged file is sorted by time.
• Tell the workers in advance that "not connected" on the screen does not mean stop. It means the data will be sent later, so they keep scanning.

Work in batches by zone

Divide the count into batches. One batch is one zone, or part of a zone, and one device. Name it with the zone code, the device number and the date, for example B-03_dev4_date. A few hundred lines is a sensible size: big enough to be efficient, small enough that a loss is not a disaster. Name one person per batch who is responsible for the upload and the check, so that nobody assumes someone else did it.

Upload, then check

When a batch is finished, go to a place with signal, such as the office, the area near the router or a mobile hotspot, and follow these steps:

1. Write on the batch sheet the number of lines and the total quantity shown on the device.
2. Upload or export the batch.
3. On the receiving side, check that the number of lines and the total quantity are the same.
4. Only then mark the batch "received" and clear the device. Never clear it before the check.

For illustration, zone C scanned on device 4 shows 312 lines and a quantity total of 4,870. If the file after upload also shows 312 lines and 4,870, all is well. If it shows 308 lines and 4,790, then 4 lines and 80 pieces are missing. The device still holds them, so send again. On a day when uploading keeps failing, the batch can be exported as a CSV file and moved to a laptop or USB drive directly. The check of line count and total is the same.

Duplicates and gaps

• Unless a recount is intended, two devices must not count the same locations in the same period.
• When a device changes hands at a shift change, close the batch and start a new one under a new name. A batch containing two people's records is hard to check later.
• Resending must not create duplicates, so use device, time, location and item as the key. Remove exact duplicates, but only after checking them.
• Compare the list of locations that should be scanned with the locations actually scanned, to find any that are missing, which means an unscanned area.

Backups

At the end of the day, export a CSV file and keep it in two places: the device's storage and a laptop or USB drive. Keep the devices well charged. If a device freezes or restarts in the middle of work, first check that the last few lines scanned are still there, and then carry on. Data that has been saved survives even if a battery runs flat. Put the date and the device number in the name of each backup file, so it is clear which one is the latest.

Summary

Even in a warehouse with poor signal, three habits keep a count steady: store locally, work in batches and reconcile. Smart Inventory collects scan results by location on mobile terminals and delivers the raw scan log, with location, item, quantity and scan time, together with the results.