It's good that your scale displays the weight on its screen, but the real leap in productivity comes when that weight automatically travels to your PLC, SCADA, or ERP: no manual entry, no errors, and in real time. In this guide, we explain how a scale integrates with your system, the role of Modbus, and the Moxa gateways we use at DeProdeCa.
Why integrate the scale with the PLC or ERP?
- Zero typing errors: the weight enters your system automatically.
- Traceability: each weighing is recorded with product, batch, date, and time.
- Automation: the PLC can start conveyors, valves, or dosing based on weight.
- Real-time data: instant stock, production, and shipping control.
The challenge: the scale speaks "serial," your system speaks "network"
Most weight indicators communicate via RS232 or RS485 serial ports. In contrast, modern PLCs and ERPs operate over an Ethernet network. This is where a "translator" is needed to connect both worlds.
The protocols: Modbus RTU and Modbus TCP
- Modbus RTU: the industrial standard over serial (RS485). Many indicators have it as standard.
- Modbus TCP: the Ethernet version, which your PLC or SCADA usually "understands."
The goal is for the weight to exit the indicator via Modbus RTU (serial) and reach your system via Modbus TCP (Ethernet).
The solution we use: Moxa gateways (serial to Ethernet)
At DeProdeCa, we connect our clients' scales to their PLCs and ERPs using Moxa gateways, which are highly reliable industrial serial to Ethernet converters. The Moxa takes the serial signal from the indicator (RS232/RS485, Modbus RTU) and publishes it on the network as Modbus TCP, so any PLC, SCADA, or ERP can read it as another device.
Advantages of this solution:
- Works with almost any scale or indicator with a serial port, even if it doesn't have its own Ethernet.
- Allows the weight to be transmitted remotely over the factory network.
- Robust and industrial equipment, designed to work 24/7.
- Easy to integrate into existing installations, without changing the scale.
Typical integration architecture
A typical setup looks like this:
Scale (load cells) → Weight indicator (RS485, Modbus RTU) → Moxa Gateway → Ethernet Network (Modbus TCP) → PLC / SCADA / ERP
Other integration methods
- Indicator with native Ethernet: some indicators already include Modbus TCP and connect directly to the network.
- Analog output (4-20 mA or 0-10 V): useful if the PLC prefers to read the weight as an analog signal.
- Digital inputs and outputs: for start, stop commands, or threshold signals between the indicator and PLC.
Do you want to send weight data to your PLC or ERP?
At DeProdeCa, we integrate scales and indicators with PLCs, SCADA, and ERPs using Modbus and Moxa gateways. We analyze your installation, select the appropriate indicator and converter, and get it up and running, with our own technical service (SAT).