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LionPOS

Scale, drawer & customer display

What you’ll find here

Section titled “What you’ll find here”
  • Pair each “peripheral” device (cash drawer, scale, label printer, customer display).
  • Test each from the device card.
  • Read the activity log when something misbehaves.

I. Cash drawer

Section titled “I. Cash drawer”

The cash drawer opens automatically when a cashier closes a sale and the printer finishes the receipt. The pulse travels through the receipt printer (most drawers piggyback on the printer’s RJ12 port).

IfDo
Drawer doesn’t open after a saleCheck the receipt printer is paired and reachable. The pulse goes printer → drawer.
Drawer opens during shift close onlyThat’s expected — the drawer also opens when the shift auto-closes.
Drawer opens randomlyMis-wired RJ12 — only the pulse pin should be connected.

For shift cash counts, see Work shifts — the Close flow requires typing the counted cash and the system reconciles against the expected amount.

II. Scale

Section titled “II. Scale”

Used for weighed products (produce, meat, cheese). Pair via USB / serial.

FieldValue
Namee.g. “Backroom scale”.
ConnectionUSB device path or serial COM3 / /dev/ttyUSB0.
Baud rateMatch your scale (commonly 9600 or 4800).
ProtocolCAS, Mettler, Generic 12-byte — depends on your scale brand.
Read unitkg / g / lb.

To use: in the POS workspace, pick a product that has “Track by weight” enabled. The POS reads the scale on every add-to-cart. The weight appears in the cart panel.

Most stores without a scale should leave scale products off the menu; mis-typed weights are the #1 cause of stock drift in weighed-item categories.

III. Label printer

Section titled “III. Label printer”

The label printer prints barcode shelf labels. Pair via USB or LAN depending on the model.

Workflow:

  1. POS workspace → More → Barcode labels (or Items → Products → Print labels).
  2. Pick products → the system generates a Code128 barcode from the client submit id (not the numeric orders.id — see Code128 rule).
  3. The label printer prints the slip with the product name + price + barcode.

If you sell to customers who rely on EAN-13, see the Code128 vs EAN-13 rule before changing the barcode format.

IV. Customer display

Section titled “IV. Customer display”

The customer display is a secondary screen that shows the running cart total, payment amount, and change due. Pair via the POS bridge running on the lane PC.

Most customer displays are USB-driven LCD panels (e.g. Epson DM-D, generic 20x2 VFD). The bridge reads the model from USB and pushes the cart snapshot on every cart change.

If your display shows the wrong amount after a discount, check that applied discounts propagate through the cart line items, not just the status pill.

V. Test from the device card

Section titled “V. Test from the device card”

Each device card has a Test button:

  • Cash drawer — pulses the open signal. The drawer pops open.
  • Scale — reads the current weight and shows it in the card.
  • Label printer — prints a 1-line test slip.
  • Customer display — pushes “TEST” to the screen.

If any of these fail, the POS bridge is the first place to look — see POS bridge & ECR Hub.

VI. Common pitfalls

Section titled “VI. Common pitfalls”

Cash drawer opens during a refund. Expected. The drawer also pulses for refunds.

Scale weight reads 0. The serial port is right but the baud rate is wrong. Try 9600 first; check the scale’s spec sheet.

Label prints the wrong barcode. You’re using a product that was created from a numeric orders.id legacy path. Reprint via the Code128 lane flow — see POS — technical.

Customer display freezes. Restart Vendor Desktop. The WebSocket session is one-to-one with the bridge; a stale session blocks new pushes.

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