Sell by weight with scales

Bitta Retail POS sells items by weight, such as coffee beans or produce, with three ways to capture the weight: a live serial scale connected to the register through the browser's Web Serial interface, manual entry by the cashier, or a weight embedded in a barcode. This page sets up the first two and shows what the cashier does at the register. For weighted barcodes, see Barcode setup.

Prerequisites

• The BAA POS - Admin or BAA POS - Full permission set to edit POS Setup, terminals, profiles and items.
• For a live scale:
  • Google Chrome or Microsoft Edge on the register device. When the browser does not offer Web Serial, the register shows "Web Serial is unavailable. Use manual weight or Chrome/Edge on HTTPS."
  • The register opened over HTTPS, as the message above says.
  • A scale with a serial or USB-serial connection that speaks the Generic Line, NCI or CAS protocol, and its port settings (baud rate, data bits, parity, stop bits, unit).
• For each weighed item, a unit of measure for the weight (for example KG or LB) assigned to the linked Business Central item.

Set up weighed items

1. Search for POS Setup and open the Scales FastTab:
   • Enable Live Scales: terminals whose Scale Mode is Inherit use a live scale. Off by default.
   • Allow Manual Weight: cashiers may type a weight. On by default; an item can still block it.
   • Scale Stable Reading Count (default 3) and Scale Stable Tolerance (default 0.005): how many consecutive stable readings, within this difference, the register needs before it accepts a weight.

2. Search for POS Terminals, select the terminal, and choose Scale Setup. (From the POS administrator role center, Terminal Scale Setup lets you pick the terminal first.) On POS Terminal Scale Setup, set Scale Mode to Inherit (follow POS Setup), Disabled or Web Serial. When the terminal resolves to Web Serial, the Web Serial FastTab appears:

   Field	Default	Values
   Scale Protocol	Generic Line	Generic Line, NCI, CAS
   Scale Baud Rate	9600	Greater than zero
   Scale Weight Unit	Kilogram	Kilogram, Pound
   Scale Data Bits	8	7 or 8
   Scale Parity	None	None, Even, Odd
   Scale Stop Bits	1	1 or 2

Match these to the scale's own settings. Flow control is always off; there is no setting for it.

3. Open the register profile on the POS Register Profile Card and turn on Weighed Item Capture on the Hardware FastTab. The Standard Checkout and Order and Fulfillment templates leave it off, so weighing does not appear on the register until you turn it on. See Setups by store type.

4. Open each weighed item on the POS Item Card. On the Weighing FastTab, turn on Sold by Weight, set Scale UOM Code (required, and it must be a unit of measure of the linked Business Central item), and optionally Default Tare Weight and Block Manual Weight. The item is priced per Scale UOM Code, and the confirmed net weight becomes the line quantity.

Supported protocols

Scale Protocol	Message the scale sends
Generic Line	A 19-character line such as ST,GS,dddddddd,kg ending in carriage return and line feed. ST is stable and US unstable; OL or UL means overload or underload.
NCI	The NCI SCP-12 style. The register asks for a weight with W and carriage return every 300 ms and reads status bits for stability, over-capacity and calibration errors. A negative weight is refused.
CAS	A 22-character message ending in carriage return and line feed, with the status at the start.

The unit in each message must match Scale Weight Unit, otherwise the register shows "The scale reported unit ..., but the terminal expects ...". All parsing happens on the Business Central server, so readings are checked the same way on every device.

Weigh at the register

Weighing starts when the cashier taps or scans a sold-by-weight item, or changes the quantity of a weighed line (which reopens it as a reweigh). The Capture weight dialog shows Gross, Tare (from Default Tare Weight) and Net.

• Live scale: the first time you weigh after opening the register, choose Connect scale. The browser asks you to pick the serial port; browsers allow this only in response to a click, so it cannot happen automatically. The connection then stays open until you choose Disconnect or close the register. The dialog reads the scale continuously, counts stable readings until the Scale Stable Reading Count is reached, and then enables Confirm.
• Manual weight: type the gross weight and choose Use manual weight. It is accepted at once, without a stability wait.

Choose Confirm to add the line. The quantity is the net weight in the item's Scale UOM Code, and the cart line shows a Scale weight, Manual weight or Barcode weight badge. The sale line keeps the Quantity Source, Gross Weight and Tare Weight, and kitchen labels print the weights. See Kitchen tickets and labels.

Common messages

Message	What to do
Web Serial is unavailable. Use manual weight or Chrome/Edge on HTTPS.	Open the register in Chrome or Edge, or use manual weight.
Scale selection was cancelled.	Choose Connect scale again and pick the port.
The scale reading does not match the configured ... protocol.	Check Scale Protocol and the port settings against the scale.
Net weight must be greater than zero.	Place the item on the scale, or check Default Tare Weight.
Manual weight entry is not permitted by POS Setup or the item policy.	Turn on Allow Manual Weight, or clear Block Manual Weight on the item.
The terminal does not have an active Web Serial scale configuration.	Set the terminal's Scale Mode, or turn on Enable Live Scales for inheriting terminals.

For more help, see Troubleshooting.

What's next

Monitor the app and diagnose problems: Audit and telemetry.