In the field of industrial automation, the continuous development of automation networks has filled us with yearning for “one network to the end”, expecting to comprehensively and detailedly read the information of each component in the network and conduct fault diagnosis through one network. However, the current technical conditions and economic costs have brought many challenges to this “expectation”. Taking the commonly used PROFInet as an example, if the goal is to achieve a one-stop network, then from each limit switch and photoelectric switch to each motor driver, all need to integrate PROFInet ports and protocols. This point seems somewhat impractical both technically and economically.
From a technical perspective, taking the S7-1515 series as an example, it can support up to 256 PROFInet slave stations at most. In large-scale automation scenarios, the total number of various switches, sensors, drivers, etc. far exceeds this figure of 256. From an economic perspective, if ordinary sensors and switches are all integrated with PROFInet interfaces, it means that the cost will increase significantly and the appearance size will also need to be redesigned.
The sudden emergence of the IO-Link protocol
As early as 2008, the IO Link protocol was incorporated into the IEC 61131-9 standard and officially became an open communication protocol in the field of industrial automation. It adopts a two-wire communication method to transmit the status information and diagnostic information on simple sensors to the IO Link master station. Then, the IO Link master station is converted to the upper-layer industrial network protocol, such as PROFInet, EtherCAT, etc. In this way, the goal of “one network to the end” can be achieved both technically and economically.
In 2022, IO Link Safety made its official debut at the SPS exhibition in Nuremberg, Germany, incorporating functional Safety into the scope of IO Link. As a result, sensors, switches, actuators, etc. related to functional safety on the equipment can be integrated into the automation network through the IO Link Safety protocol. The IO Link Safety protocol complies with the IEC 61139-2 (Industrial Networks – Single Point Digital Communication Interface – Part 2: Functional Safety Extensions) standard and can meet the safety level requirements of EN ISO 13849-1 PLe and IEC 61508/62061 SIL 3.
The pain points of traditional secure network architectures
Before the launch of IO Link Safety, we usually connected safety-related sensors, switches and actuators to a fieldbus/network site (IP67 or IP20), from which simple status information (ON/OFF) of each device was transmitted upwards or each actuator was controlled (ON/OFF). From the perspective of communication, it has not reached the field layer of sensors and actuators. Therefore, many diagnostic information at the field layer cannot be obtained by the controller, such as the temperature of the safety switch, the supply voltage of the safety light curtain, and the remaining action cycle life of the actuator.
The advantages of IO-Link Safety
With the IO Link Safety protocol, manufacturers of Safety sensors and safety actuators can easily integrate the IO Link Safety protocol into safety components using the two-wire principle. These Safety components can be easily connected to the automated network, such as PROFInet, EtherCAT, etc., after being connected to the IO Link Safety Master site via simple 2-wire cables. Such a network architecture will not overly occupy the number of sites of the upper-layer network protocol – only the IO Link Safety Master site will be occupied, and it will not significantly increase the price and cost of the original safety components.
IO-Link Safety can bring more optimized communication and security guarantees for industrial automation. It solves the pain points of the traditional security network architecture, realizes the effective integration of technology, economy and functional safety, and is an important step for the industrial automation field to move towards “one network to the end” and intelligent and safe development. As a well-known brand in the field of Safety automation, PILZ’s hardware products for the IO Link Safety protocol will be launched successively this year, including the IO Link Safety Master master station. Advanced Safety light curtains with IO Link Safety interfaces and PITgatebox button units integrated with IO Link Safety interfaces, etc. Let’s look forward to them!
