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Scales

Admin

Brother POS supports USB scales for weighing products sold by weight at the register. Scales connect via the Web Serial API, which means the POS communicates with the scale directly through the browser -- no drivers or middleware needed. Scale integration is an optional feature controlled by a feature flag.

Hardware Settings

Prerequisites​

Before setting up a scale:

  1. Enable the Scale feature flag under Settings > Edit Settings > Hardware & System tab.
  2. Use Google Chrome or Microsoft Edge as your browser. The Web Serial API is not supported in Firefox or Safari.
  3. Have a USB scale that outputs weight data over a serial connection.

Supported Scales​

Brother POS works with USB scales that provide serial output. Most digital POS scales support this.

ScaleConnectionNotes
CAS SW seriesUSBCommon in dispensaries. Reliable serial output.
My Weigh iBalanceUSBCompact, good for small products.
Ohaus ValorUSBIndustrial-grade, very accurate.
Any serial-output USB scaleUSBMust output weight readings over serial/COM port.
Scale Accuracy

For cannabis sales, use a scale with at least 0.1g precision. Many dispensary scales offer 0.01g precision, which is preferred for compliance.

How It Works​

  1. The cashier selects a weight-based product in the POS.
  2. The POS prompts to read the weight from the scale.
  3. The cashier places the product on the scale.
  4. Brother POS reads the weight via the Web Serial API.
  5. The weight is used to calculate the price (price per gram x weight).
  6. The product is added to the cart with the measured weight and calculated price.

Setting Up the Scale​

Step 1: Connect the Scale​

  1. Plug the USB scale into an available USB port on your POS device.
  2. Power on the scale.
  3. Allow it to calibrate (most scales auto-calibrate on power-up).

Step 2: Enable Scale in Brother POS​

  1. Log in to the Admin Panel.
  2. Navigate to Settings > Edit Settings > Hardware & System tab.
  3. Toggle Enable Scale to On.
  4. Click Save.

Step 3: Pair the Scale in the POS​

The first time you use the scale, the browser will ask for permission to connect:

  1. Open the POS register at storename.brotherpos.ca/pos.
  2. Add a weight-based product to the cart (or use the scale function in the product detail view).
  3. The browser displays a "Select a serial port" dialog.
  4. Choose the USB serial device that corresponds to your scale.
  5. Click Connect.

The browser remembers this selection, so you will not need to re-pair the scale on future visits (unless you clear browser data or use a different browser).

Browser Permissions

If the serial port dialog does not appear, your browser may be blocking the Web Serial API. Check that:

  • You are using Chrome or Edge (not Firefox or Safari).
  • The site is served over HTTPS (required for Web Serial API).
  • No browser extensions are blocking serial port access.

Baud Rate Auto-Detection​

The Web Serial API requires a baud rate to communicate with the scale. Different scales use different baud rates.

Automatic Detection​

Brother POS attempts to auto-detect the correct baud rate by trying common rates:

Baud RateCommon On
9600Most scales (default)
4800Some older CAS models
2400Some basic scales
1200Older or specialized models

The auto-detection process:

  1. Brother POS tries each baud rate in sequence.
  2. It passively listens for valid weight data frames -- it does not send any command to the scale.
  3. When a valid response is received, that baud rate is saved for future use.

Manual Baud Rate Setting​

If auto-detection fails:

  1. Check your scale's manual for the correct baud rate.
  2. In the POS scale settings, manually select the baud rate.
  3. Test the connection by placing a known weight on the scale.
Finding the Baud Rate

If you cannot find the baud rate in your scale's manual, try the most common value first: 9600. This works with the majority of POS scales.

Using the Scale at the Register​

Weighing a Product​

  1. Tap a weight-based product in the POS (products configured to sell by weight).
  2. The weight input panel appears.
  3. Place the product on the scale.
  4. Tap Read Scale to capture the weight from the connected scale.
  5. The weight appears in the input field.
  6. Tap Add to Cart.

The price is calculated automatically: Price = Price Per Gram x Weight.

Manual Weight Entry​

If the scale is unavailable, disconnected, or malfunctioning, cashiers can enter the weight manually:

  1. Tap the weight-based product.
  2. Instead of tapping Read Scale, type the weight directly into the weight field using the on-screen numpad.
  3. Tap Add to Cart.
Manual Fallback

Manual weight entry is always available, even when a scale is connected. This ensures that a scale malfunction never blocks sales.

Taring the Scale​

Before weighing a product:

  1. Place the container (bag, jar, etc.) on the scale.
  2. Press the Tare button on the physical scale to zero out the container weight.
  3. Add the product to the container.
  4. Read the weight in Brother POS.

Brother POS reads whatever weight the scale reports. Taring must be done on the physical scale itself.

Weight Presets vs. Scale​

For common pre-packaged weights (1g, 3.5g, 7g, 14g, 28g), you can use weight presets instead of the scale:

  1. Enable weight presets in Settings > Edit Settings > Products & Inventory tab.
  2. Configure presets under Cannabis > Weight Presets.
  3. When adding a weight-based product, cashiers see preset buttons alongside the scale option.
  4. Tapping a preset sets the weight without using the scale.

This is faster for pre-packaged products. Use the scale only when a customer orders a custom weight that does not match a preset.

See Weight Presets for configuration.

Troubleshooting​

"No Serial Port Found" Error​

  1. Check the USB connection -- Is the scale plugged in and powered on?
  2. Check the browser -- Are you using Chrome or Edge?
  3. Check HTTPS -- The Web Serial API requires a secure (HTTPS) connection.
  4. Try re-pairing -- Clear the serial port permission in browser settings and try connecting again.

Scale Reads 0.00g With Product On It​

  1. Check the scale display -- Does the physical scale show a weight? If not, the scale itself has an issue.
  2. Check the baud rate -- An incorrect baud rate can cause the POS to misread the data. Try auto-detect or manually set the baud rate.
  3. Check the serial cable -- Some USB-to-serial adapters can cause issues. Try a different adapter or direct USB connection.

Weight Readings Are Inconsistent​

  1. Place the scale on a flat, stable surface away from vibrations or drafts.
  2. Calibrate the scale using a known weight (see the scale's manual for calibration instructions).
  3. Wait for the scale reading to stabilize before tapping "Read Scale." Most scales have a stability indicator.

Scale Works in Text Editor but Not in POS​

If the scale outputs readable data in a terminal program but not in Brother POS:

  1. The data format may not match what Brother POS expects. Brother POS expects a standard weight output format.
  2. Check the scale's output mode -- it should be in "continuous" or "request" mode, not "print on demand."
  3. Contact support with your scale model for compatibility assistance.

Common Questions​

Can I use a Bluetooth scale? The Web Serial API primarily supports USB serial connections. Some Bluetooth serial profiles may work, but USB is the reliable option. Use a USB scale for the best experience.

Do I need a scale at every register? Only at registers where weight-based products are sold. If all your cannabis is pre-packaged, weight presets may be sufficient and no scale is needed.

What happens if the scale disconnects mid-sale? The cashier can enter the weight manually to complete the sale. The manual fallback ensures no sale is blocked by a hardware issue.

Can the scale auto-read when I place a product on it? No. The cashier must tap Read Scale to capture the weight. This is intentional -- it prevents accidental weight readings and ensures the cashier verifies the weight before adding it to the cart.

What's Next?​