Practical, vendor-neutral how-to guides for ESL deployment. The information here applies to ZKong ESLs sold by Retail Digitals; most of it also applies to other major ESL platforms with minor terminology differences. Updated 2026-05.
Install your first ESL — a 15-minute walkthrough
~5 min read · zero prior experience needed
Before you commit to a store-wide rollout, deploy one ESL on one shelf. The process below is the fastest path from "label in the box" to "label on the shelf showing the right price."
What you need on hand
- One ESL (any series — Quantum, Arrow, Shield, Valley, Blade, or Essence)
- One cloud-platform login (provided when you place your order)
- Smartphone with the configuration app installed (download link in your welcome email)
- Wi-Fi or cellular signal for the smartphone
- ~15 minutes
You do not need a gateway for the first-label test — the smartphone app pairs the ESL directly via Bluetooth, then sends the first content payload. A gateway is only required for ongoing updates after the smartphone walks away.
The steps
- Take the ESL out of the package. The screen will show the factory image (logo or QR code). The label is already powered on; coin-cell batteries ship pre-installed.
- Open the app on your phone, log in with the credentials in your welcome email, and tap "Pair new device."
- Hold the phone within ~3 feet of the ESL. The app scans for nearby labels — the ESL's serial number appears on screen within 10-15 seconds.
- Tap the serial to select. The app asks: "Assign to which SKU?"
- Either scan the product's barcode with the phone camera, or pick the SKU from the list. The platform finds the price + description.
- Tap "Send to label." The screen on the ESL refreshes (a brief flash, then the new content appears) within 2-5 seconds.
- Done. The label is now showing the correct price. Snap it onto the shelf rail.
Once you've done one, you've done them all. Bulk pairing for a full store works the same way but uses the gateway as the relay instead of your phone.
Gateway placement: how many you need and where to mount them
~6 min read · plan before you order
Gateways are the wireless hubs that relay content from the cloud platform to every ESL in the store. Get this right and labels update in seconds; get it wrong and you'll see retry queues and stale prices on the far side of the store.
How to estimate quantity
The rule of thumb most US deployments use:
- Up to 10,000 ESLs and ~10,000 sq ft of selling floor: 1 gateway, mounted centrally.
- 10,000-30,000 ESLs and ~10,000-30,000 sq ft: 2-3 gateways, spread evenly.
- Over 30,000 ESLs: 1 gateway per ~15,000 ESLs as a starting estimate. Always validate with a site survey.
The actual coverage depends on what's between the gateway and the labels. Metal racking, refrigeration units, walk-in freezers, and concrete walls all attenuate the 2.4 GHz signal. A 15,000 sq ft warehouse-style store with low racking can sometimes run on a single gateway; a 5,000 sq ft pharmacy with metal medicine cabinets may need two.
Where to mount
Gateways need power (typical PoE Ethernet or wall AC) and line-of-sight to as many labels as possible. The ideal placement:
- Above the ceiling tiles, dropped 6-12 inches below. Gives near-full-store coverage from one device.
- On structural columns, 8-12 ft above floor. Second-best when ceiling mount isn't possible.
- Avoid mounting: directly above metal HVAC ducts, against exterior walls, inside metal cabinets, or below 7 ft (shoppers will block signal).
Power and network requirements
| Requirement | Typical spec |
|---|---|
| Power | PoE+ (802.3at) or 12V DC adapter — gateway draws ~10W |
| Network | Ethernet — outbound HTTPS to cloud platform on port 443. No inbound port forwarding needed. |
| Bandwidth | Negligible — full-store nightly sync is typically <5 MB |
| Backup connection | Optional — gateways can fall back to LTE modem add-on if Ethernet fails |
Site survey: do you need one?
For deployments under 5,000 ESLs in a single floor < 10,000 sq ft, you can usually skip a formal survey and start with one gateway centrally mounted. For larger or multi-floor stores, request a survey before ordering — it's free and prevents the "we're 200 labels short of full coverage" problem after install.
ESL attachment options: rails, magnets, screws, adhesive
~4 min read
How an ESL physically attaches to your shelves matters more than people expect. The wrong choice creates labels that fall off, get stolen, or don't fit between adjacent SKUs. There are four primary attachment methods. Pick by shelf type, not by preference.
Standard shelf rail clip
Plastic clip that snaps onto the front lip of a wire or solid shelf. The label slides into the clip; clip stays on the shelf when shelf is restocked.
Magnetic mount
Strong rare-earth magnet on the back of the ESL. Attaches to any ferrous metal surface in <2 seconds.
3M VHB adhesive
Pre-applied double-sided foam tape. Permanent attachment. Removal leaves residue.
Screw / wall mount
Two screw holes in the rear plate. Most secure, also most permanent.
For freezers and coolers specifically, use the freezer-rated Shield Series with the rated freezer clip — standard clips become brittle below 0°C and will snap when stocking.
Pairing ESLs to the cloud platform
~5 min read
"Pairing" means associating each physical ESL with a specific SKU in the cloud platform. This is what tells the platform: "send the price for SKU 12345 to label serial number XYZ." It happens once per label.
Two ways to pair
One-by-one (smartphone app): for the first 10-50 labels, this is fastest. Open the app, scan the SKU barcode, scan the ESL serial barcode, tap "pair." The label updates in seconds.
Bulk pairing (CSV upload): for store-wide deployment, you upload a CSV with two columns: esl_serial, sku. The platform pairs all rows in one operation. This is what big chains use.
Where ESL serial numbers live
- Printed as a barcode on the back of every label
- Printed on the box (one row per label inside)
- Available in the platform under "Unassigned devices" once a label first wakes near a gateway
For chains with planograms, you typically pair labels by walking the aisle with a Bluetooth scanner: scan shelf-edge SKU barcode, scan ESL serial, repeat. A two-person team can pair 3,000-4,000 labels per day with this workflow.
Re-pairing when a SKU moves
When a product changes shelf location, you re-pair the label, not move the physical label. Open the platform, find the old pairing, and re-assign to the new SKU. The label updates within seconds via the gateway.
Sending price updates from your POS or ERP
~6 min read
Once labels are paired and gateways are live, the only remaining piece is the price feed: how does the platform know when a price changes?
Three feed methods
See the integrations page for the full breakdown of supported POS / ERP systems. The three methods are:
- Real-time REST API webhook — best when prices change frequently (dynamic pricing, promotional periods, fresh-food markdowns)
- Scheduled CSV / SFTP — best for stable pricing with daily or hourly batch updates
- Manual web UI upload — best for pilots, single-store deployments, or stores doing manual price entry
Test the feed before going live
Always run a "shadow" feed for 1-2 weeks before relying on ESL prices at the register. The platform has a "preview" mode where price changes are received but not pushed to labels — you can compare the platform's price against the register's price for every SKU and catch any data-mapping mistakes before customers see them.
Handling promotional prices
Most POS systems track regular and promotional prices as separate fields. Configure the platform's label template to:
- Show regular price normally
- Show promo price + "WAS $X" overlay during a promo period
- Auto-revert to regular after promo end date
This is set per template, not per label — once configured, all labels of that template behave identically.
Common deployment problems and how to fix them
~5 min read
| Problem | Likely cause | Fix |
|---|---|---|
| Labels in one section never update | Gateway signal blocked by metal racking or freezer wall | Add a second gateway near that section, or relocate the existing gateway to higher ceiling mount. |
| Prices on shelf differ from POS | Stale price feed, wrong SKU pairing, or template logic bug | Check the platform's "feed log" for the SKU. If feed is current, re-verify the ESL-to-SKU pairing. |
| Labels fall off shelves | Wrong attachment for shelf type | Switch to magnet mount on metal shelves, screw mount on high-theft areas, VHB on glass. |
| Some labels have a faint "ghost" of the previous image | Normal e-paper behavior after many partial refreshes | Trigger a full refresh from the platform — solves it within seconds. Schedule weekly full refresh as preventive. |
| Pairing app can't find a label | Label is in deep sleep (no recent gateway contact) | Press the small button on the back to wake the label. |
| One specific label keeps going offline | Battery near end-of-life (after several years) | Replace the coin-cell battery. Platform will flag low-battery labels in advance. |
| Cloud platform shows label as "missing" but it's on the shelf | Label hasn't checked in within the heartbeat interval (typically 24h) | Trigger a "ping" from the platform. If still missing after 5 min, check gateway signal in that area. |
Stuck on a deployment problem not covered here?
Our New York team handles US deployments end-to-end. Reach out with the specifics of your store and stack — we'll either solve it on a call or schedule a site visit.
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