Weighing indicators for load cells and force transducers

Weighing indicators for load cells and force transducers display weight exactly where the operation takes place: as DIN-standard front-panel mounted units in control cabinets, or in enclosed housings for wall, table, and column mounting. Featuring keypads, setpoints, and relay outputs for dosing and filling processes, they are available in versions compliant with OIML R76 Class III and MID for legal-for-trade applications.

Weighing indicators for load cells and force transducers for front-panel mounting and housings

The first decision is the design type, and it depends on where the operation will take place.

Front-panel mounting units in DIN formats 96 x 48 and 96 x 96 mm are installed in the control panel and fit existing cutouts. This is the right choice if a control console or cabinet is already available and the scale is part of a larger system. Pay attention to the ingress protection rating: the rating provided refers to the front panel, which is usually IP54. The rear side with the terminals is protected inside the cabinet, which is why front-panel mounting only works in wet areas if there is a corresponding housing behind the panel.

Housed units provide their own protection. Made of polycarbonate, ABS or AISI 304 stainless steel, with cable glands and an ingress protection rating of up to IP68, they can be mounted on walls, columns, or tables. They are necessary wherever there is wash-down, dust accumulation, or no control cabinet nearby: in shipping and receiving, food production, agriculture, and for floor scales in open areas.

Does the indicator need to be legal-for-trade?

As soon as the weight serves as the basis for a price, invoice, or official quantity, the entire scale must undergo conformity assessment, not just a part of it. A certified load cell combined with an arbitrary display unit does not result in a certified scale. The indicator is an explicit component of the system.

You can find the relevant certifications in our data sheets: OIML R76 Class III describes the accuracy class for non-automatic weighing instruments and covers virtually all industrial applications, from floor scales to vessel weighing. The specification of verification intervals—up to 10,000 for our certified devices—limits the permissible resolution during legal-for-trade operation: the certified scale may not display more scale intervals than this, even if the electronics are technically capable of higher resolution. Certification according to OIML R61 in conjunction with WELMEC Guide 8.8 covers automatic gravimetric filling instruments, i.e., dosing applications.

It is important to distinguish between "legal-for-trade capable" and "verified": legal-for-trade capable means the device meets the requirements and can be verified. The initial verification of the assembled scale is performed separately, for which the cell and indicator must be compatible. Check this with us before purchasing to avoid ending up with a scale that works technically but cannot be verified.

For purely internal monitoring, process control, and recipe management without any commercial relation, no certification is required. In that case, resolution, speed, and functional scope are what matter.

Determining readability

Character height determines the reading distance. As a rough guideline, an LED digit can still be read reliably from about 200 times the digit height; at 14 mm, that is just under three meters with good visibility and no backlight. If the value needs to be seen from ten meters away, from a forklift, or from a ramp, you do not need a larger indicator, but rather a remote display driven in parallel.

Red LED displays remain easier to read than LCDs in halls with changing lighting conditions and dust. Additional status LEDs and symbols save the operator from having to interpret numerical values, such as for stand-still indication, zero point, and tare.

Dosing, filling, and recipes

This is where the real difference compared to a simple display unit lies. Using setpoints and relay outputs, the indicator controls coarse and fine feed during filling by itself, without the need for a PLC to intervene. Digital inputs capture zero-setting, taring, and start-stop commands from external buttons.

Versions with multi-program functionality manage up to 99 recipes for single and multi-component dosing. This pays off in feed, construction, and food production, where multiple mixtures are processed alternately, because the operator selects the formula via a step switch or keypad and starts it without having to change parameters. A clock and calendar function, as well as a printer connection, provide the associated receipt.

Connection to the controller

Serial interfaces with Modbus RTU and ASCII are standard; Ethernet TCP/IP allows remote access and configuration from a PC or tablet; fieldbuses are available depending on the version or can be supplied upon request. An analog output is optional on some devices.

If no one needs the value on-site and it is only a matter of transmitting it to the controller, a weighing transmitter in the control cabinet is the more compact and cost-effective solution. For mobile testing and service tasks, handheld devices and wireless systems are ideal.

Matching components

You can find sensors under load cells and force transducers, and complete systems under ready-to-use scales. We calibrate cells in our own laboratory according to ISO 17025.

Price, data sheets, and CAD models are available online for every item. Our engineers will advise you directly on the selection of design, certification, and dosing functions.