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Connect Scales to Square Point of Sale

Connect and troubleshoot your supported CAS PD-2 USB scale with Square Point of Sale.

Before you get started:

Note: The CAS PD-2 USB scale is not supported with Square for Retail, Square for Restaurants, and Square Appointments apps.

National Measurement Institute Certified Sticker

Square has produced a sticker indicating the scale connection to our Point of Sale has been certified by the National Measurement Institute (NMI). When you purchase a USB scale or the cables through Square Shop, you will have been supplied a sticker with the NMI certification number.

You must clearly place this sticker on the device running the Square Point of Sale app (i.e. Square Stand, Android tablet/smartphone or Square Terminal). The sticker helps NMI field inspectors identify that Square has fulfilled all compliance regulations for the certification from the National Measurement Institute. Contact Square Support if you need a complimentary replacement sticker.

Supported Hardware

The CAS PD-2 USB scale is compatible with:

Hardware Compatibility
Square Stand* ✔️
Square Terminal with Hub ✔️
Square Register ✖️
Android with Square Reader ✔️
iOS with Square Reader ✖️

*Note: The CAS PD-2 USB scale is compatible with Square Stand for the following iPads at this time: 9.7” iPad (2017, 2018), iPad Pro 9.7”, or iPad Air (1, 2). Not sure which iPad model you have? Identify your iPad.

For a list of all compatible hardware by device, check out our supported third-party hardware accessories.

Connect Your USB Scale

What you need for Square Stand

For Square Stand, a successful connection requires the following:

  • Micro USB to USB-A cable
  • Null modem adapter/null modem cable
  • Serial to HID adapter
  • National Measurement Institute certified sticker

Connect your Square Stand

To connect the CAS PD-2 scale to your Square Stand:

  1. Plug the 9-pin male end of the serial-to-HID adapter into the null modem adapter/null modem cable. Then plug the male end of the null modem adapter/null modem cable into the port on your scale. To keep the adapter firmly connected, twist the security screws into place.
  2. Plug the micro-USB end of the cable into the adapter, and plug the USB-A side of the cable into the USB accessory hub on Square Stand.
  3. To check the connection, open the Square Point of Sale app and tap the three horizontal lines.
  4. Tap Settings > Hardware > Scales.
  5. The connected scale should appear in the app menu as USB Scale.

What you need for Square Terminal and Android

For Square Terminal* and Android**, a successful connection requires the following:

  • D-sub to USB-A cable
  • Null modem adapter/null modem cable
  • National Measurement Institute certified sticker

*Square Terminal also requires the Hub for Square Terminal.
**Requires either a micro USB on the go (OTG) adapter or USB-C OTG adapter depending on the port on your Android device.

Connect to Square Terminal

  1. To connect the CAS PD-2 scale to your Square Terminal:
  2. Plug the 9-pin male end of the D-sub cable into the female end of the null modem adapter/null modem cable. Then plug the male end of the null modem adapter/null modem cable into the port on your scale. To keep the adapter firmly connected, twist the security screws into place.
  3. Insert the USB-A male end of the D-sub cable into the Hub for Square Terminal.
  4. To check the connection, open the Square Point of Sale app and tap the three horizontal lines.
  5. Tap Settings > Hardware > Scales.
  6. The connected scale should appear in the app menu as USB Scale.

Connect to Android

To connect the CAS PD-2 scale to your Android device:

  1. Plug the 9-pin male end of the D-sub cable into the female end of the null modem adapter/null modem cable then the male end of the null modem adapter/null modem cable into the port on your scale. To keep the adapter firmly connected, twist the security screws into place.
  2. Insert the USB-A male end of the D-sub cable into the female end of the OTG adapter.
  3. Insert the male end of the OTG adapter into the USB port on your Android device.
  4. To check the connection, open the Square Point of Sale app and tap the three horizontal lines.
  5. Tap Settings > Hardware > Scales.
  6. The connected scale should appear in the app menu as USB Scale.

Unpair Scale

To unpair your scale:

  1. Open the Square Point of Sale app and tap the three horizontal lines. From Square Register, tap the down arrow.
  2. Tap Settings > Hardware > Scales.
  3. You’ll see your connected scale — tap Disconnect to unpair.

Note: The Square Point of Sale app can only connect to one scale at a time.

Troubleshoot Your USB Scale

  • Confirm you’re using the CAS PD-2 USB Scale with supported iPads with Square Stand, Square Terminal, or an Android smartphone or tablet.

  • Make sure your Square app is up to date. The latest version of the Square app for Android is required to connect to the scale.

  • Ensure you’ve correctly set up Items to sell by weight.

  • Check that you have a secure connection between your scale, cables, adapters, and any additional connected accessories.

  • Make sure you’re using the correct cables for your scale. The cable is included in the scale but if you need a replacement, purchase a Square Stand USB cable and Square Terminal or Android USB cable via Square Shop.

Note: The CAS PD-2 USB scale needs to be in ECR-5 mode to work properly.

To ensure your CAS PD-2 scale is set up in the right ECR (Extended Control Register) mode:

  1. With the scale turned off, hold the T key and turn the scale on.

  2. When Ecr SEt appears, release the T key.

  3. The display will show tyPE X, where X is the current type setting. Use the * key to select type 5.

  4. Press the 0 key to save.

  5. Turn the scale off then back on again.

Label Printing Scales

Square supports the ability to scan UPC-A and EAN-13 barcodes printed from standalone label printing scales, such as the CAS CL5500R-30 Label Printing Scale. We do not currently support the ability to connect a label printing scale directly with your Square hardware in order to program labels or integrating with catalog capabilities. Note: This compatibility is only available for iOS devices at this time.

These barcode labels are issued with both item SKU information as well as the total weight or price of an item. When items with these types of barcodes are scanned, the item’s weight and price information are automatically captured without the need for manual calculation.

The format for UPC-A and EAN-13 barcodes is 0-2AAAAA-BBBBB.

The first five digits of the barcode (i.e. AAAAA) is an item code that matches the SKU entered in for an item on the point of sale. For example, if your item code is 00123, this portion of the barcode will also read 00123.

The last five digits of the barcode (i.e. BBBBB) represents the total price of an item in cents. So, an item that is $12.34 would read as 01234. This value is used to calculate weight, with the minimum value being $0.01 and the maximum value being $999.99.

Note: The first digit will be 0 for EAN-13, but for UPC-A, the 0 is not required. The second digit will always be 2.

For any questions or troubleshooting enquiries regarding your third-party hardware, please contact CAS directly.

Learn more about scanning barcodes from label printing scales.

Learn more about: Square Hardware

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