serial-nci-scale

Serial NCI Scale

An API to query a Serial Scale which supports the NCI protocal (SCP-12, NCI 3825, NCI 3835). Tested against the Salter Brecknell PS-USB scale. Depends on the Web Serial API.

Getting Started

Page Hosting the library must be served over HTTPS. Demo is available at https://chris-rudmin.github.io/serial-nci-scale/

Installation

npm install serial-nci-scale --save

Instance Methods

• getWeight() - Returns a promise which resolves with scale weight data. Required to be called from user action
• getStatus() - Returns a promise which resolves with scale status data. Required to be called from user action
• zero() - Returns a promise which resolves when the scale is zeroed. Required to be called from user action
• startPolling() - Starts polling the scale for weight data every 250ms. Required to be called from user action
• stopPolling() - Stops polling the scale
• disconnect() - Returns a promise which resolves once disconnected. Closes the read and write streams and frees the serial port

Example

import SerialNCIScale from 'serial-nci-scale';

const scale = new SerialNCIScale();
const { weight, units, status } = await scale.getWeight();

Events

The serial-nci-scale instance is an EventTarget and can be listened to for custom events. Scale data is contained the in the detail property.

• weight - Dispatched for every weight read
• status - Dispatched for every status read
• settled - Dispatched when the scale is no longer in motion and if the weight is different than the last settled weight

Supported Browsers

Currently only Chrome 89+ supports the Web Serial API. Earlier versions of Chrome can use the API if it is enabled in chrome://flags