Behind the smoothly running factory, there are conversations that go unheard. Machines talk to each other all the time: sensors report to controllers, controllers command actuators, and screens in the control room display everything. This silent language has a name, and one of the oldest yet most enduring is Modbus.
For many automation technicians in Indonesia, understanding communication protocols like this often distinguishes between merely being able to program a PLC and truly being able to build a fully connected system.
Modbus: an irreplaceable legacy protocol
Modbus was introduced by Modicon in 1979, long before the term Internet of Things became popular. Yet, it is still used everywhere today. The reason is simple: it is open, lightweight, and easy to implement. There are two forms that are most commonly encountered. Modbus RTU runs over RS-485 serial cables, reliable for long distances in electrically noisy factory environments. Modbus TCP/IP runs over Ethernet networks, faster and easier to integrate with modern information systems. Understanding when to use which is a fundamental skill that is often underestimated.
From PLC to HMI and SCADA screens
The PLC is the brain that executes logic in the field, but humans need a window to monitor it. This is where HMI plays a role, displaying machine status on a touchscreen near the production line. Taking it a step further, SCADA collects data from multiple PLCs simultaneously, providing a comprehensive view of the entire factory from a single control room. The integration of PLCs to HMI and then to SCADA transforms a stack of separate devices into a single system that can be monitored and controlled. Without a neat communication protocol, all those layers would just be islands that do not communicate with each other.
Industry 4.0 needs more skilled hands
Through the Making Indonesia 4.0 roadmap, the government encourages national manufacturing to adopt automation and data connectivity. However, advanced machines are useless without people who understand how to connect them. The demand for technicians who master both PLCs and industrial communication continues to rise, while formal curricula often lag behind field practices. As a result, many young engineers learn through trial and error on their own, even though the foundation could be laid out from the start.
As long as factories rely on machines that must be interconnected, the ability to make them “talk” to each other will remain a sought-after skill. This silent language of the factory can indeed be learned, and that is where its value lies.
References:
- Modbus Organization – Modbus Application Protocol Specification → modbus.org
- Schneider Electric – Modicon PLC and Modbus communication guides → se.com
- Kementerian Perindustrian RI – Making Indonesia 4.0 → kemenperin.go.id