Control & Automation Digital Weight Transmitters – PLC & SCADA Weight Integration
Digital weight transmitters for control and automation applications convert the analogue millivolt signal from one or more load cells into a standardised output — 4–20 mA, Modbus RTU, Profibus DP, EtherNet/IP, or RS-485 — that feeds directly into a PLC, SCADA, DCS, or process controller. Unlike a weight indicator with a local display, a digital weight transmitter is designed purely for system integration: it sits in a control panel or on a DIN rail, delivers a clean, noise-immune weight signal to the control system, and can be configured and calibrated remotely via software or fieldbus communication without physical access to the device.
In process control and automation environments, the accuracy and reliability of the weight signal is critical — it drives valve positions, conveyor speeds, batching sequences, alarm states, and production records. Digital transmitters eliminate the signal degradation and interference that can affect long analogue cable runs from load cells to control panels, and their onboard digital filtering and corner correction functions ensure the PLC receives a stable, accurate weight value even in electrically noisy industrial environments. Multi-channel models allow signals from multiple load cells or vessels to be monitored simultaneously from a single device, simplifying panel design and reducing wiring complexity.
Our range covers single and multi-channel transmitters with the most common industrial communication protocols, including models with ATEX certification for hazardous area process control installations in Zone 1, Zone 2, Zone 21, and Zone 22. Whether you are integrating a new tank weighing system into an existing Siemens, Allen-Bradley, or Schneider PLC architecture, or upgrading an older analogue installation to digital fieldbus communication, our technical team can advise on the correct transmitter specification for your load cell configuration, protocol requirements, and control system.
Key Features
- 4–20 mA analogue output for direct, protocol-agnostic integration with any PLC or DCS input card
- Modbus RTU (RS-485) for digital weight data, tare, and setpoint communication with compatible PLCs
- Profibus DP and EtherNet/IP for integration with Siemens, Allen-Bradley, and other major automation platforms
- DIN-rail and panel-mount formats for clean, compact control panel installation
- Onboard digital filtering and corner correction for stable, accurate weight signals in noisy environments
- Remote configuration and calibration via PC software or fieldbus — no physical access required
- Multi-channel models for simultaneous monitoring of multiple vessels or load cell groups
- ATEX-certified models for Zone 1, 2, 21, and 22 hazardous area process control
- Wide load cell excitation range compatible with all standard analogue load cells
Common Applications
- Tank and silo weight integration with PLC-controlled process systems
- Automated batching and dosing — weight-triggered valve, pump, and conveyor control
- Loss-in-weight and gain-in-weight feed rate monitoring and control
- Multi-vessel inventory monitoring from a single SCADA screen
- Reactor and process vessel weighing in chemical and pharmaceutical automation
- Conveyor and hopper weighing integrated with production line PLCs
- Hazardous area process weighing in ATEX-classified zones
All transmitters are sourced from leading manufacturers and are compatible with our full range of load cells, mounting modules, and junction boxes. Contact our technical team for advice on protocol selection, load cell compatibility, and PLC integration support for your specific control system.
Frequently Asked Questions
What is the difference between a 4–20 mA output and a Modbus output for PLC integration?
A 4–20 mA analogue output represents the weight as a proportional current signal — simple, noise-immune, and compatible with virtually every PLC analogue input card without any special configuration. It is the most universally compatible method but carries only a single value (the weight reading) and requires the PLC to scale the current to engineering units. A Modbus RTU output is a digital communication protocol that allows the PLC to read multiple parameters from the transmitter — weight, tare, gross, status flags — and to write commands such as tare and zero back to the transmitter. Modbus is preferred for more complex integrations where bidirectional communication or multiple data values are required.
Which PLCs are compatible with these transmitters?
Our transmitters support the most widely used industrial communication protocols — 4–20 mA, Modbus RTU (RS-485), Profibus DP, and EtherNet/IP — which are natively supported by all major PLC platforms including Siemens S7 and TIA Portal, Allen-Bradley ControlLogix and CompactLogix, Schneider Modicon, Mitsubishi MELSEC, and Omron. The correct transmitter model depends on which protocol your PLC uses and which input cards are available — contact our team with your PLC make, model, and available communication modules for a specific recommendation.
Can a digital weight transmitter handle signals from multiple load cells?
Yes. Most transmitters in our range include an internal summing function that accepts signals from multiple load cells — typically up to 8 — connected via an equalisation junction box, and outputs a single combined weight signal to the PLC. Multi-channel models are also available for applications where signals from multiple vessels or load cell groups need to be monitored simultaneously from a single device and reported as separate weight values to the control system.
How is a digital weight transmitter calibrated without physical access?
Most modern digital weight transmitters support theoretical (or parameter-based) calibration, where the load cell sensitivity (mV/V), capacity, and number of cells are entered via PC configuration software or fieldbus communication — no test weights are required. This is particularly valuable for large tanks and silos where applying physical test weights is impractical. Deadweight calibration (using known test weights) is also supported for applications where the highest accuracy is required. Both methods can typically be performed remotely via the fieldbus connection from the control room.
Are ATEX-certified transmitters available for hazardous area process control?
Yes. We supply ATEX-certified digital weight transmitters approved for Zone 1, Zone 2 (gas and vapour hazards) and Zone 21, Zone 22 (combustible dust hazards). These are required for process weighing and automation in chemical plants, pharmaceutical facilities, fuel storage, and grain handling environments where flammable atmospheres may be present. Contact our technical team before specifying equipment to confirm the correct zone classification, equipment category, and communication protocol for your installation.
