4 Common Industrial Automation Protocols to Connect Embedded Computers on the Factory Floor


The hype and buzz around industry 4.0 and its newest technology drivers for smart manufacturing is  on the horizon.  Some of the largest industrial manufacturing  applications are at the forefront of tackling major challenges  by leveraging real-time decision making and data analysis through the use of faster, better  technology; This now includes power-efficient  processor performance that is decentralized and less reliant on the direct communication with major data centers or  the infrastructure of the “cloud.” This new shift provides a huge benefit to industrial automation applications that leverage the ability for real-time monitoring, logging or even real-time decision making; a  rapid deployment model in factory infrastructures that utilize automation and robotics. For example, many industrial automation facilities that scale with many large volume manufacturing can leverage robotics to provide better productivity and efficiency  for specific tasks, allowing humans to  focus on other critical  tasks in the operation.

 In addition to newer automation technology, there are some key fundamental industrial computing protocols that  have been standardized for efficient communication topology between industrial computers, sensors, and devices that are implemented into the architecture of  automated industrial controls for manufacturing.  These common protocols are pivotal in understanding  how  industrial equipment in factory floors are connected to a central programmable  logic  controller or “PLC”  that  drives critical communication systems for stable operation and production.


What is the Fieldbus Protocol?

To efficiently control and manage all the devices and sensors required in a complex automated industrial environment, fieldbus was created as the family of communication protocols used. One of the critical requirements for factory operation, such as manufacturing assembly line, is real-time distributed control and hierarchy. For example, a temperature sensor may be used to trigger an alarm when the temperature exceeds a certain threshold; when that alarm is tripped, the signal needs to be transmitted to the appropriate device so action can be taken. If there is any delay in the signaling, the results may be catastrophic. Fieldbus protocols were designed to address some of the unique challenges of connecting multiple devices in an industrial factory. There are various popular fieldbus protocols used today depending on the factory environment and the connectivity requirement.


What is the PROFIBUS Protocol?

Process Field Bus is the most widely adopted fieldbus used in the automated process industry today. There are two variants of the PROFIBUS used today: PROFIBUS DP and PA. The more common used protocol is PROFIBUS DP (Decentralized Peripherals); this is used to communicate between the controller and the various sensors/actuators used for production automation applications. PROFIBUS PA (Process Automation) is mainly used to monitor measuring equipment. Both DP and PA share the same protocol, so they can be used interchangeably. In addition to the real-time control signals, one of the benefits of using PROFIBUS is its extensive diagnostics messages send between devices; this enables the operator to monitor the health status of each device in to real-time for preventative maintenance. PROFIBUS was designed for expandability as the maximum number of connected devices is 126.


What are the EtherCAT, EtherNet/IP, and PROFINET Protocols?

Due to the proliferation of ethernet-based network for communication, newer and modern fieldbus protocols were developed based on ethernet technology: EtherCAT, EtherNet/IP, and PROFINET. These protocols use the same standard ethernet cabling in the data link/networking layer but changes the application layer to be better suited for industrial automation and process control. Two of the main advantages of these ethernet-based fieldbus are: speed and the maximum number of devices. Because these protocols are using the same ethernet physical layers, speeds can go up to 1Gbps, compared to PROFIBUS maximum speed of 12Mbps. For EtherCAT, the maximum number of devices is 65,536, while for both EtherNet/IP and PROFINET it is almost unlimited. Due to its high transmission speed, these protocols offer extremely low cycle time (less than 100 microseconds), which translates into very precise time synchronization (less than 1 microsecond) between all devices . For factory applications that requires close to real-time update and synchronization between the controller and devices, these protocols are used in favor of PROFIBUS or CANopen.


What is the CANopen Protocol?

This protocol was developed primarily for motion control system; the main applications for CANopen is for motor and robotics controllers. CANopen is based on the CANbus protocol, which is primarily used in automotive applications. The advantage of this protocol is it can leverage the existing hardware and cabling used in CANbus. CANopen sits somewhere in between PROFIBUS and the various ethernet-based fieldbus with a maximum speed of 1Mbps and up to 127 devices.