Modbus is a serial and Ethernet communication protocol widely used in industrial automation for data exchange between master and slave devices, such as PLCs, sensors, actuators, frequency inverters, SCADA systems, and test equipment.
Created in 1979, it remains today as an open and robust standard, ideal for simple, stable, and highly interoperable networks.
🔌 Most Used Types of Modbus
| Version | Physical Interface | Main Characteristics |
|---|---|---|
| Modbus RTU | RS-485 or RS-232 | Fast and compact binary serial communication |
| Modbus ASCII | RS-232/RS-485 | Text-based serial communication, more readable |
| Modbus TCP/IP | Ethernet | Modern version over IP networks, ideal for integration with SCADA or ERP systems |
⚙️ Protocol Characteristics
- 📡 Master-slave communication (or client-server in TCP)
- 🎯 Read/write operations on coils, registers, digital and analog inputs
- 🧱 Simple structure: short binary commands with CRC for integrity check
- 🔁 Support for multiple devices (up to 247 in RTU)
- 🔧 Easy implementation in microcontrollers, PLCs, industrial PCs, and embedded systems
🧩 Typical Applications
- Control and monitoring of industrial sensors and actuators
- Supervision of HVAC systems, lighting, energy, and fluids
- Communication with inverters, meters, smart relays
- Automation of test benches with control of sources, loads, I/O, and equipment
- Integration with SCADA, MES systems, and maintenance software
🔧 How AJOLLY Testing Supports Your Project with Modbus
AJOLLY Testing designs and implements testing, acquisition, and automation solutions with full support for Modbus RTU and TCP, integrating industrial equipment, embedded systems, and test platforms.
🛠️ Application Development with Modbus:
- Master or slave communication via LabVIEW, C#, Python, TestStand, Arduino, or PLCs
- Support for specific libraries and industrial automation drivers
- Creation of Modbus device simulators for firmware testing
- Validation of communication under different load, noise, or timeout conditions
🧪 Functional and Compliance Testing
- Automation of tests on devices with Modbus RTU or TCP interface
- Verification of commands, responses, CRC, framing error, and integrity
- Creation of parameterized test scripts with technical tolerances and limits
- Automatic generation of reports with logs and KPIs (response time, failure rate, communication integrity)
🔗 Integration with Larger Systems
- Data logging in SQL database or remote servers via Modbus TCP
- Field device control via real-time tests
- Export of results to MES, ERP systems, or custom dashboards
- Support for production traceability with serial number and detailed logs
With AJOLLY Testing, you can automate the validation of any equipment using Modbus, ensuring reliability, reproducibility, and robust technical documentation — from engineering to production.