The Benefits of Using Modbus RTU Over TCP for Industrial Automation

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In today's fast-paced industrial automation landscape, reliable and efficient communication between devices is crucial for smooth operation and optimal productivity. When it comes to choosing a protocol that can meet these demanding requirements, Modbus RTU over TCP stands out as an excellent choice.

What Is Modbus?

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Modbus (Manufacturers' Address-Bus) is an open industrial automation bus protocol used extensively in programmable logic controllers (PLCs), remote terminal units (RTUs), and other field devices for process control. It was originally developed by Schneider Electric's Automation division as a simpler alternative to the more complex Modbus-Plus and FierceBus protocols.

Why Choose Modbus RTU Over TCP?

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Modbus RTU over serial lines or twisted pair cables has been widely used in industrial applications due to its robustness, simplicity, and low cost. However, with the increasing need for greater distances between devices while maintaining high data rates, Modus/TCP emerged as a viable alternative.

Key advantages of using Modbus RTU over TCP include:

1. Reliability: Unlike Ethernet-based protocols like EtherNet/IP or Profibus-IP which are vulnerable to electromagnetic interference (EMI), Modbus RTU operates at the physical layer and is therefore immune from such disturbances.

2. Low Latency: Because it runs on top of reliable serial interfaces, Modus/TCP offers lower latency compared with IP-based protocols that must contend with Layer 3 routing overheads.

Modem Options for Long-Range Communication

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For applications requiring long-range communication beyond the reach of traditional twisted pair or fiber optic cables, wireless options become necessary. In this context, two popular choices are:

1. 900MHz Industrial Ethernet Wireless Radio Modems: These modems offer high data rates (up to 500K baud) while maintaining excellent range and punch through capabilities compared with more commonly used WiFi frequencies like 2.4GHz.

Example Use Cases

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Here are some real-world scenarios where Modbus RTU over TCP could be deployed:

1. SCADA Systems: Supervisory Control And Data Acquisition (SCADA) systems often require reliable, long-range communication between remote substations and central control centers.

2. Industrial Process Automation: In continuous process industries like oil & gas or chemical plants, real-time monitoring and control demands are high; Modbus RTU over TCP meets these requirements effectively.

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In conclusion, when choosing a protocol for industrial automation applications that require reliable long-range communication while maintaining low latency, Modbus RTU over TCP stands out as an excellent choice. Its robustness, simplicity, low cost combined with the availability of suitable modem options make it ideal for use in demanding SCADA and process control environments.

References

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For more information on programming a S7-1200 Profinet integrated port to a Modbus TCP/RTU gateway or other related topics, refer to these forums:

* Accessing MODBUS RTU device through gateway from MODBUS TCP in S7-1200.

* S7-1200 Problems trying to communicate with modbus RTU device trough .

Modbus rtu over tcp