This industrial crane scale is one of the long-running projects ECK has been involved in, covering embedded electronics, wireless communication, cost reduction and technology upgrades.

The work was not limited to developing an electronic board. The aim was to help build the client’s technical team, organize the development process and take part in creating the company’s first products.

One of the first projects was an industrial crane scale with a capacity of up to 10 tons, high weighing resolution and wireless communication.

The device went through many evolutions over the years and became a product with a long commercial life.

Crane scale: development and evolution

The scale was specified for a capacity of 10,000 kg with 10,000 divisions, which corresponds to a division of roughly 1 kg.

This requirement placed high demands on the combination of load cell, acquisition circuit, mechanics and electronic processing.

During testing, it was even necessary to work with increments of around 500 grams, an extremely small value compared to the scale’s total capacity of 10 tons.

Achieving stability and repeatability under these conditions required attention to electrical noise, acquisition resolution, mechanical stability, external interference and the characteristics of the load cell itself.

The load cell problem

Another major challenge lay in the scale’s own mechanics.

Most load cells available at the time were designed to work mainly in compression. A crane scale, however, required a solution suited to tension operation.

Several mechanical alternatives were studied, but they did not deliver the expected performance.

The solution came when an HBM load cell suitable for this type of application became available.

It was a sealed, high-precision cell that made it possible to achieve the performance the product required.

Load cell signal acquisition

The first versions used acquisition and digitization hardware also supplied by HBM.

This solution offered the performance needed to develop and validate the product, but it represented a significant share of the scale’s final cost.

As the project evolved, alternatives for the load cell digitization circuit were studied.

Later, the system was replaced by a lower-cost solution that preserved the performance the application needed.

This kind of evolution is common in industrial products: first you prove the solution technically, then you work on optimizing the architecture and the production cost.

Wi-Fi in an industrial product in 2002

One of the project’s differentiators was Wi-Fi communication, something still rare in industrial equipment at the time.

A Rabbit module was used to implement this connectivity.

The link allowed the scale to send data to other systems and to be operated remotely.

Data could be sent in XML format, making it easier to integrate with supervisory and production management systems, including SAP-based environments.

Communication in high-interference environments

The industrial application brought another important challenge.

Some scales were installed in plants with many induction furnaces, equipment capable of producing high levels of electromagnetic interference.

Under these conditions, the wireless link had to be carefully designed.

Antenna placement, communication architecture, electronics immunity and the device’s behavior under interference all became part of the development.

The goal was not just to keep the link working, but to make sure the radio systems did not compromise the device’s main function: measuring weight.

Remote control at 434 MHz

The product also used communication in the 434 MHz band for some remote control functions.

The first solutions had limitations in range and interference immunity in the industrial environment.

As the project evolved, the link was improved by using an SRWF-1021 multichannel spread spectrum transceiver, better suited to the conditions found in the application.

This change made the wireless link more robust and was part of the product’s continuous evolution.

Metrological certification

Certification was also an important stage of development.

Since this was a high-capacity, high-resolution scale that included radio communication systems, it had to be shown that external interference, or interference from its own electronics, could not improperly change the weighing result.

The tests for approval by Inmetro, Brazil’s metrology authority, required special attention precisely because they combined metrology with electronic features and wireless communication that were still uncommon in this type of equipment.

Display readable from a distance

The application also required the operator to be able to read the weight from a considerable distance.

For this, a display with high-brightness, wide-viewing-angle LEDs was developed, suited to the industrial environment.

The goal was to ensure good readability even when operator and scale were a significant distance apart.

Product evolution

Over the years, different parts of the architecture were revisited.

The changes included:

• improvement of the load cell acquisition system;
• component replacement to reduce costs;
• evolution of the 434 MHz link;
• use of Wi-Fi communication;
• integration with external systems through structured data;
• replacement of the processor with an ARM Cortex-M3 based solution;
• refinements based on field experience with the product.

The purpose of these changes was not simply to modernize the electronics, but to maintain the product’s performance and reliability while reducing its manufacturing cost.

Engineering consulting and team development

In this project, ECK’s role went beyond electronic development.

The work, which began in 2002, also involved helping train and organize Weightech’s engineering team.

ECK took part in architecture analysis, problem solving, component selection, testing and the product’s technology evolution.

This interaction between the client’s in-house team and the consultancy meant the knowledge gained stayed within the company and could be applied to the products that followed.

A product with more than two decades of evolution

The crane scale became a long-lived commercial product for Weightech.

Since development began in 2002, the architecture has gone through several updates, keeping pace with the evolution of electronic components, communication technologies and the need to reduce costs.

More than two decades later, the product is still on the market.

This history shows an important trait of an industrial electronic project: good development does not end with the first prototype.

It has to allow for production, certification, maintenance, cost reduction and technology evolution over the years.

See also how ECK works on electronic product development.