Digital scales used load cell sensor and HX711 module

Article in bahasa

This article will discuss a simple measurement system which is one of the tasks subjects Instrumentation namely digital scales. This object's mass measurement system using the sensor load cell, module and Labview HX711 as a viewer. Here is the hardware of the system:

The sensor used is 2 kg load cell and as a reinforcement of the sensor output load cell used HX711 module which is a module voltage amplifier and ADC (Analog to Digital Converter). As a data processor, it is used to display information Arduino and measurement values used LabView. Here is a system block diagram:

Each block explanation are as follows:

1. Load cell which is able to change the weight sensor pressure transducers (force) into an electrical signal. There are three ways to change the value of the load cell pressure (force) received into a measurement value, namely hydraulic load cell, pneumatic load cell and strain gauge load cell. In this digital weighing system used a strain gauge load cell. The output of this sensor in the form of voltage in mV legible order to change the resistance value represents weight of the object.
2. HX711 Module is a module that allows us to read load cell in the measurement of weight. This module serves to amplify the output signal from the sensor and converts analog data into digital data. By connecting it to the microcontroller, we can read the change in resistance of the load cell. After the calibration process we will gain weight measurement with high accuracy.
3. The Arduino as a data processor will read the data output of the module HX711. Because the output of the module is already in the form of gram HX711, this causes fairly mild arduino workload. Results of earlier readings subsequently rounded to the nearest 0.5 and sent to Labview.
4. Labview will recieve data from arduino and will display the data on PC monitor.

The HX711 is a small module offers a lot of convenience. The module has three grades reinforcement, i.e. gain of 32, 64 and 128. However, these digital scales used for a gain of 128 are by connecting the output of the sensor on channel A module. This module uses the interface "two wire" that clock and data to communicate. To facilitate reading data from HX711, it is also provided a library that can be used. The other advantages of this module HX711 is a simple structure, easy to use, the results are stable and reliable, has high sensitivity, and is capable of measuring changes quickly. To obtain more complete information about HX711 modules please see here.

For the interface, you can choose to use the assembled LCD bundled with hardware digital scales. But in this system, I use LabView to display the measurement results of the system. Here is the interface of digital scales using labview:

And this is the VI diagram:

Finally.. to see the system as a whole, please see the following video:

You can get the arduino code and labview diagram in this link. 

Referensi:

Putra, Agfianto Eko. 2015. Basic Sensor and Transducers. Materi Kuliah Instrumentasi. Yogyakarta.

https://learn.sparkfun.com/tutorials/getting-started-with-load-cells
https://cdn.sparkfun.com/datasheets/Sensors/ForceFlex/hx711_english.pdf 
https://www.sparkfun.com/products/13230?_ga=1.24748345.2083688779.1444095746

https://learn.sparkfun.com/tutorials/load-cell-amplifier-hx711-breakout-hookup-guide