The idea behind a modular load cell kit is straightforward: instead of buying a finished scale, you bring the weighing capability to whatever structure you are already working with. A steel platform, a pallet frame, a tank, a hopper, a silo — if it is rigid and bears a load, it can become a calibrated weighing system.

This guide walks through how to do that in practice, from choosing the right kit and mounting the sensors, to connecting the electronics and calibrating the system. It covers both the GRAM WM (for platforms up to 8,000 kg) and the GTAM MK (for tanks and silos up to 20,000 kg).

If you are still at the stage of understanding how load cells work and what types exist, start with our introduction: Load Cells Explained.

Choosing the right kit for your application

The first decision is which kit fits your application. The two systems are designed for fundamentally different installation contexts.

The GRAM WM is built around four H8C Rebel shear-beam load cells. It is designed for platforms — floor scales, pallet scales, machine bases, workbenches, or any flat rigid structure where a load sits on top. The cells mount directly to the underside of the structure using the supplied screws, and the feet below each cell make levelling straightforward. Available in capacities of 4 × 500 kg, 4 × 1,000 kg, or 4 × 2,000 kg, the system covers total weighing ranges from 2,000 kg up to 8,000 kg.

The GRAM MK uses four dedicated weighing modules designed for process installations — tanks, hoppers, and silos where the structure sits on top of the modules rather than the other way around. The modules include built-in stabilisers that compensate for vibration, and an anti-tip system for structural safety. Available in capacities of 4 × 1,000 kg, 4 × 2,500 kg, or 4 × 5,000 kg, it supports total loads up to 20,000 kg. Both nickel-plated steel and AISI 304 stainless steel versions are available for food or chemical environments.

Both kits include the same Xtrem digital module and IP67-rated stainless steel junction box, and both support cable or Wi-Fi connectivity.

What comes in the box

Both kits ship as complete systems. Understanding what each component does before you start makes the installation faster and avoids common wiring mistakes.

The four load cells or weighing modules are the sensors. Each one measures the portion of the total load resting on that corner. The Xtrem module combines all four readings into a single, accurate weight value.

The junction box (IP67 stainless steel, 189 × 78 × 43 mm) is where the four sensor cables meet before connecting to the Xtrem module. It handles the signal routing between cells and module. Its IP67 rating means it can be hosed down or installed in wet environments without risk.

The Xtrem digital module (140 × 67 × 33 mm) is the brain of the system. It converts the raw sensor signals into a digital weight reading, stores all calibration data internally, and handles communication to indicators, PCs, or the network. This is important: if the module is ever replaced or swapped to another installation, the calibration data goes with it.

Step 1: Preparing the structure

For the GRAM WM, the platform needs to be rigid, flat, and load-bearing only through the four cell mounting points. This last point is critical: if any part of the structure is resting on the floor, a wall, a pipe, or anything other than the four load cells, that contact point will carry part of the load and the measurement will be wrong. The platform must be entirely supported by the four cells — nothing else touches.

Recommended structures: welded steel frames, thick steel plate, or robust wooden platforms. Avoid anything that flexes significantly under load, as deformation in the structure introduces measurement error independent of the sensors.

For the GRAM MK, the preparation is in the foundation. The four module base plates must sit on a flat, level concrete or steel surface. Any tilt at the base transfers as a side load into the modules, reducing accuracy and potentially stressing the sensors over time. If the surface is uneven, shim or grout before installing.

In both cases, check that no pipes, cables, hoses, or guide rails are mechanically connected to the structure being weighed. Anything that creates a fixed connection between the weighed structure and the surrounding environment will carry part of the load away from the sensors.

Step 2: Mounting the sensors

GRAM WM Xtrem cells mount at the four corners of the platform underside. Position them symmetrically — equal distance from the edges on all sides. Use the supplied screw sets (included as a set of four for each cell). Mount on a flat surface; if the mounting surface is uneven, the cell body will be stressed before any load is applied. Tighten to contact and add a quarter turn — do not overtighten, as this preloads the sensor.

The load must act vertically downward through the cell. The H8C Rebel is a shear-beam sensor and handles incidental side loads well, but the primary load direction must be vertical. Once mounted, check that the platform sits level. The adjustable feet on the GRAM WM cells allow fine levelling at each corner.

GRAM MK modules mount differently. The tank or silo leg sits on top of the module, which sits on the foundation. Each module has defined upper and lower contact surfaces — the load path must be clean and vertical through both interfaces. Bolt the lower plate to the foundation, then place the upper saddle in contact with the structure leg. Do not weld the structure to the modules. The anti-tip cable connects the module to the structure leg and prevents tipping under eccentric loading, but it carries no weighing load — keep it loose enough that it only engages if the structure shifts.

Fit the stabilisers between adjacent modules after all four are in position. These connect the modules laterally and reduce the effect of vibration from filling, agitation, or nearby machinery on the weight reading.

Step 3: Wiring the junction box

Run the four sensor cables to the junction box. Each cable is labelled or identifiable by position. Connect them to the corresponding terminals inside the box following the wiring diagram included with the kit. The junction box IP67 seal must be properly closed after wiring — check that the cable glands are tightened and the lid gasket is seated correctly.

From the junction box, a single cable runs to the Xtrem digital module. Connect this to the module input. Power the Xtrem module either from 230V/50 Hz mains or at 7.5V DC — or draw power from a compatible indicator if one is connected.

For data output, the Xtrem module communicates via RS-232 as standard. Optional Wi-Fi connectivity can be added, enabling data transmission to any device on the local IP network simultaneously with the cable connection. Transmission speed is configurable from 9,600 to 115,200 baud.

Indicator compatibility note: The GRAM Z8 and GRAM Z8i Weighing Terminals and the GRAM K3 and GRAM K3i indicators are compatible with Xtrem digital equipment (both cable and Wi-Fi versions). When selecting a weighing terminal or indicator to pair with either kit, make sure it is explicitly marked as Xtrem-compatible.

Step 4: Calibration

Both kits use the Calready system, which means the sensors are factory-calibrated and the Xtrem module stores all calibration data. In practice, this means you can connect the system and get a meaningful weight reading immediately — without needing calibration weights on site.

However, for applications requiring verified accuracy, a conventional span calibration using reference weights is recommended after installation. This accounts for the specific mechanical conditions of your installation — the structural stiffness, the exact position of the cells, any residual preload from assembly. The Xtrem PC software and iOS/Android app (both free) include a guided calibration procedure with Adjust Zero and Adjust Span functions visible directly in the interface.

For the GRAM MK in particular, electronic calibration without weights remains possible after initial setup — useful for re-calibrating after maintenance without needing to move large reference loads to the installation site.

The Xtrem module’s internal resolution is 500,000 divisions, with a speed of 12 samples per second and a linearity error below 0.0001%. External resolution depends on the capacity variant selected. The system supports up to two measurement ranges and two measurement steps, configurable via the software.

Step 5: Data connection and software setup

Once the system is weighing correctly, connect it to your data environment. The Xtrem module supports RS-232 and optional Wi-Fi. The free Xtrem PC software connects via cable and provides live weight display, calibration tools, and data logging. The free iOS/Android app connects via Wi-Fi and offers the same core functions for mobile access.

For integration into automation or PLC systems, the RS-232 output transmits weight data continuously at the configured baud rate. The digital module stores all calibration and adjustment parameters internally, so the data connection only carries live weight values — there is no configuration dependency on the connected system.

Common installation mistakes and how to avoid them

Parasitic load paths. The single most common cause of inaccurate readings is a mechanical connection between the weighed structure and something fixed — a pipe, a cable tray, a conveyor belt, or a support bracket that was left in contact during installation. Before commissioning, physically check that nothing touches the weighed structure except the four sensors.

Uneven mounting surfaces. Shear-beam cells and weighing modules both require flat mounting. A 1 mm step under a cell corner introduces a permanent mechanical offset and can cause the cell to read differently under the same load at different positions.

Overtightening mounting screws. Excessive torque on the cell mounting screws introduces mechanical stress into the sensor body before any load is applied. Follow the torque specification in the installation sheet, or tighten to contact plus a quarter turn.

Ignoring the 75–80% capacity rule. Each cell or module has a defined nominal capacity. For safe long-term operation, the total working load should not exceed 75–80% of the combined nominal capacity. For a 4 × 1,000 kg system (4,000 kg total), the practical safe working load is around 3,000–3,200 kg. Operating above this range does not necessarily cause immediate failure, but it shortens sensor life and increases non-linearity at the top of the range.

Wrong indicator model.Ensure you are using a compatible device. The GRAM Z8 and GRAM Z8i Weighing Terminals and the GRAM K3 and GRAM K3i indicators are compatible with the Xtrem digital module.

Sensor replacement and maintenance

One advantage of both systems is that sensors can be replaced without dismantling the entire installation. For the GRAM MK, the module design allows the sensor element to be swapped while the support structure remains in place. Since calibration data is stored in the Xtrem digital module rather than the individual sensors, replacing a faulty cell does not require a full recalibration from scratch — though a verification calibration is recommended after any sensor change.

The junction box IP67 rating means routine cleaning, including pressure washing in appropriate installations, does not require special protection of the electronics. Check cable glands and the lid gasket periodically in environments with vibration or thermal cycling.

What this kind of system makes possible

Once installed and connected, both kits deliver continuous digital weight data to whatever system you connect them to — PC, indicator, smartphone, or PLC. The Xtrem module supports simultaneous cable and Wi-Fi transmission, so data can go to a local display and a remote monitoring system at the same time.

For practical applications: a GRAM WM under a pallet station feeds real-time weight data to a warehouse management system. A GRAM MK under a mixing tank enables precise batching by weight rather than volume. In both cases, the kit provides the measurement infrastructure — what you do with the data depends on how you integrate it.

Need help selecting the right configuration?

If you are unsure which kit, capacity, or indicator combination fits your application, our team can help you work through the requirements. Contact us here.

For the conceptual background on load cell types, measurement principles, and system architecture, see: Load Cells Explained.