What is Modbus?

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Modbus is a serial communication protocol that was developed by Modicon. It was first published in 1979 for use with the company’s programmable logic controllers (PLCs). In basic terms, it is one of the methods used for information transmission over serial lines between electronic devices. The Modbus Master is the device that requests the information while Modbus Slaves supply the information. In a typical Modbus network, there will be one Master and as many as 247 Slaves, with every Slave Address being unique, from 1 to 247.

A Brief History Of Modbus

Before we get into the particulars regarding the use of Modbus, let’s take a look at the brief history of this platform. In the early days of industrial automation, factories required an approach for the first Programmable Logic Controllers (PLCs) to communicate with each other. The first PLC was developed in 1968 by Modicon, as per General Motors’ request. After this started to showcase effectiveness at General Motors, the device was called Modicon 084, and mass production began. This resulted in several new competitors entering the market toward the end of the 1970s, for example, Allen-Bradley was one of the main competitors that started to create such solutions, and PLCs were highly common in factories. However, information was still not being communicated via the PLCs, and there was an arms race to find out who would be the first to innovate their technology so that communication could take place between the devices. Around the same time, Modicon created Modbus while Allen-Bradley released Data Highway. However, many viewed Modbus as the grandfather of the industrial communication protocol field. When it comes to connecting automated electronic devices in industrial settings, this is the

most common method used. When Modbus was released by Modicon, the company did so without their standard licensing protocol being kept. This enabled any developer to incorporate Modbus into their products as it is a universal standard that many devices can support. It is also very easy and straight foward to understand and set up, even by those who do not have an engineering background.

What Is Modbus Used For?

Modbus is an open protocol platform, meaning, manufacturers can build their equipment free of charge without needing to pay royalties. It has become a standard communications protocol in the sector, and it is a common means for connecting industrial electronic devices. Manufacturers across a number of industries use Modbus. It is typically utilized for the purpose of transmitting signals from control and instrumentation devices back to the chief controller or data gathering system. For instance, this could be a system that measures humidity and temperature, and then communicates the results back to a computer.

Understanding How Modbus Works

Modbus is generally transmitted over serial lines between devices. The most straightforward setup involves a single serial cable that is connected to serial ports on two devices; a Slave and a Master. The data will be sent as a series of zeroes and ones called bits. Each bit is sent as a voltage. Zeroes are sent as positive voltages, and ones are sent as negatives. The bits are sent very high quality. A standard transmission speed is typically 9600 baud (bits per second).

The Modbus Organization, Inc.

The Modbus Organization has managed the development and any needed updates to Modbus protocols in an association of users and advocates of the technology ever since Schneider Electric bequeathed the rights to them in 2004. It is an independent, non-profit organization that requires membership to join. Their mission is to build the infrastructure needed for full adoption of Modbus across multiple industries by sharing information and educating users on the best practices for successful implementation.

Modbus Protocols

Several protocols for Modbus exist and are constantly evolving through experimentation and innovation from users within the Modbus Organization. Three are most commonly used, with Modbus TCP being the protocol that the Modbus Organization favors in its development and universal implementation objectives.

Modbus Protocols and IoT

The Modbus Protocols may be older than most people reading this article, but its simplicity and efficiency at powering many sectors of the manufacturing industry is still transitioning along with new advancements and innovations like the Internet of Things. Programmable Logic Controllers (PLC), Industrial Control Systems (ICS), Distributed Control Systems (DCS), and/or Variable Frequency Drivers (VFD) are all frequently seen in factories around the world. They perform actions and transmit data in real-time to manufacture many of the common household items you possess, from vehicles to breakfast cereals, and it is all communicated with Modbus Protocols. Essentially, Modbus, being by now so pervasive and adopted into millions of devices – and not just on the factory floor, but in millions of products from absolute encoders to zero-point thermometers – has already been doing what the Internet of Things (IoT) and IIoT (Industrial Internet of Things) is only now doing. The difference between them is that IoT is faster, more efficient, and more accurate at communicating information, which leads to more productivity, more cost-effectiveness, and more profits.

But this does not mean that Modbus is heading to the trash heap as IoT takes over – not for a while, anyway. Its wide adoption across so many industries all over the world cannot be dispensed with so quickly, or so easily. There are now several software companies providing solutions for Modbus and IoT integration, but only one of them has the experience and reliability to liberate your data with unparalleled connectivity, Open Automation Software.