Welding Process Monitoring & Cloud Data Reporting
Background
The project was undertaken by a system integrator and commissioned to us for development, ultimately serving the welding workshop of a Chinese manufacturer. We were responsible for hardware design and embedded software development, aiming to add current/voltage acquisition, welding process identification, threshold alarming and cloud reporting to welding machines without modifying the welding circuit.
Challenges
- The welding circuit cannot be modified: acquisition must be non-invasive and must not affect the welding process itself;
- Strong electromagnetic interference: high currents in the welding machine's internal coils can degrade sampling accuracy;
- Mixed welding machines: supply voltages vary widely, and arc welding and TIG welding are used side by side, requiring automatic identification;
- Long-term unattended operation: the device must run reliably in humid, high-interference environments and recover automatically.
Solution
Non-invasive acquisition without modifying the welding circuit
A Hall current sensor is clamped around the cable to acquire 0~500A welding current, while a closed-loop Hall voltage sensor acquires welding voltage. Both sensors are galvanically isolated between primary and secondary, leaving the welding circuit untouched.
Automatic process identification and threshold alarms
Arc welding and TIG welding are distinguished automatically from the sampled voltage. Current above the configured threshold for 6s triggers an audible and visual alarm; voltage above the 120V threshold for 2s triggers an intermittent alarm. Thresholds are remotely configurable.
Dual data channels: cloud and local
4G with MQTT provides direct cloud connectivity, while an isolated RS485 + Modbus RTU interface connects to local PLCs or gateways. Parameters can be configured remotely and firmware supports OTA upgrades.
Industrial-grade reliability
Wide input AC 100~480V with surge protection and differential/common-mode interference suppression. The device resets and restarts automatically on abnormal operation and reconnects automatically after communication failures.
Application Value
- Welding current and voltage are acquired and reported in real time, providing a basis for quality traceability;
- Welding processes are identified automatically, reducing manual judgement and record-keeping effort;
- Threshold alarms raise immediate on-site awareness of abnormal conditions;
- Remote configuration and OTA reduce long-term maintenance and upgrade costs.
Productization
The RS485 isolation circuit from this project was field-validated and productized as the RS485 Isolated Surge-Protected Castellated SMD Module XT-C-485-HIA-V3/5, now supplied as a standard module for other industrial communication applications.