What is a weighing indicator and How Do They Work?
WHAT IS A WEIGHING INDICATOR?
A weighing indicator is an external device that displays the weight of an object on a digital display. Also known as a digital weighing indicator or weighing scale display, they are a common scale component used in industrial and commercial weighing applications around the world.
Weighing indicator typically consist of a large, easy-to-read display, simple navigational buttons or a keypad, a power cord (and/or internal batteries), a communication port (such as serial RS-232), and an optional stand or panel mounting hardware.
Some weight indicators also have built-in features such as process control, data storage, statistical analysis, and networking capabilities. This allows you to collect and analyze weight data for quality control purposes or to track production trends over time.
HOW DO WEIGHING INDICATOR WORK?
Digital weighing indicator that work with analog load cells send an electrical current through the load cell and monitor the signal that comes back. They then convert that electrical signal into a digital number.
Digital weighing indicator that work with digital load cells receive weight information from a digital load cell or digital weight sensor, which they then display on the indicator. This signal is then transmitted either wirelessly or through a communication cable like RS-232 or RS-485.
WHAT ARE THE DIFFERENT TYPES OF WEIGHT INDICATORS?
There are four main types of weight indicators: digital indicators, intrinsically safe indicators, remote display indicators, and signal conditioning transmitters. Let's explore each one in further detail.
1. Digital indicators
A digital indicator is the most common type of weight indicator. It receives power from an AC power cord, AC adapter, or batteries and connects to a scale base via a load cell cable. Many digital indicators have internal batteries, which allow them to be used in portable applications or to continue displaying weight information in the event of a power outage.
2. Remote display indicators
A remote display weight indicator is similar to a digital indicator in that it displays weight information, although the displayed characters are usually very large. They are often used in connection with a digital indicator. The digital indicator sends weight data to the remote display, typically via a communication cable like RS-232.
Remote display indicators are used in weighing applications where the operator needs to be able to see the weight on the scale even when they are not next to the digital indicator. A very common application for remote displays is truck scales where the remote display is located outside while the digital indicator is inside a scale house. This way, the truck driver can verify that the scale is at “0” before they drive onto the scale for weighing.
3. Intrinsically safe indicators
An intrinsically safe weight indicator is specially designed for use in hazardous environments. These indicators are certified by a third-party testing agency (e.g., CFMus, ATEX, IECEx, etc.) to meet rigid safety standards. This ensures they will not ignite any combustible materials or create any sparks that could trigger an explosion. Many intrinsically safe indicators are also NTEP certified and can be used in legal for trade scale systems.
4. Signal conditioning transmitters
A signal conditioning transmitter (also known as a PLC weighing module) is a type of weight indicator that is designed for use with PLCs, PCs, and other automation devices. These devices are typically DIN-rail mountable within a cabinet or control panel, where they receive load cell signals and convert them into a standard analog output, a serial communication output, or a specific network protocol that can be read by the host system. This allows the weight data to be seamlessly integrated into existing process control or data acquisition systems.
COMMON USES FOR A WEIGHING INDICATOR
weighing indicator are used in a wide variety of weighing applications, including:
Industrial weight scale systems
Floor scales
Pallet jack scales
Counting scales
Checkweighers
Hanging crane scale systems
Drum scales
Scale conversion kits