IO-Link Safety: What It Is and Isn’t

Comparing “IO-Link” and “Safety” to “IO-Link Safety”

There are many I/O blocks that have “IO-Link” and “Safety” in their descriptions, which can cause some confusion about which safety features they include. Here’s an overview of different safety-named blocks and how they compare to IO-Link Safety.

Safety Network Blocks

These blocks have I/O ports that use Pin 4 and Pin 2 as OSSD signals (safety ports). OSSD—output switching signal devices—send 24-volt signals over two wires to confirm that a device is operating in a safe condition. If 0 volts are detected in either signal, besides their safety-checking 0-volt pulses, it’s read as a safety event that signals the machine to go into a safe state. Safety network blocks are only for standard (non-network) safety devices. These blocks communicate directly back to a Safety Controller over safety protocols like CIP Safety, PROFIsafe, etc. These blocks typically can monitor between 8-16 standard safety devices. There is no intelligence built into the safety devices.

Safety Network Blocks with IO-Link

Blocks in this category usually have a mixture of I/O ports on them. The ports can range from standard I/O to standard IO-Link communication, and in addition, include ports that use Pin 4 and Pin 2 as OSSD signals (safety ports). These blocks communicate over the safety protocols with only a few ports to connect standard (non-network) safety devices. There is some versatility with these blocks since you can wire standard sensors, IO-Link devices, and safety devices to it. The drawback is, you will always run short of the port style you need and, in the end, use more blocks to cover either the safety or IO-Link needs of the application. There is no intelligence built into the safety devices.

Safety over IO-Link Blocks

In this system/architecture, there are standard IO-Link Masters communicating to the Safety PLCs/Controllers over standard protocols like EtherNet/IP, PROFINET, etc. Connected to the IO-Link Ports of these Masters are Safety over IO-Link devices, currently limited to only Safety over IO-Link hubs. The Safety PLCs/Controllers communicate via safety protocols like PROFIsafe to the standard IO-Link Master, and then using the IO-Link communication channel, they bridge the gap to the Safety over the IO-Link hub via the “black channel.” These Safety over IO-Link hub’s ports use Pin 4 and Pin 2 as OSSD signals (safety ports), so standard (non-network) safety devices can be connected. This system provided a “gap filler” while IO-Link Safety was being developed. In this system/architecture, the standard IO-Link Masters allowed standard IO-Link devices and Safety over IO-Link hubs to be connected to any ports. This brought even more versatility to an application and the beginnings of the benefits of IO-Link. Still, there is no intelligence built into the safety devices.

IO-Link Safety

IO-Link Safety adds a safety communication layer to IO-Link. The difference between this and Safety over IO-Link is that this safety layer applies to both the IO-Link Master and IO-Link Safety devices. Within a CIP Safety or PROFIsafe network, the safety communication protocol has top priority over standard EtherNet/IP or PRIFONET data if both are existing on the same physical network. The same is true for IO-Link Safety: both standard and safety IO-Link protocols can exist on the same physical cable between the IO-Link Master ports and IO-Link Safety devices, with IO-Link Safety carrying the top priority. For a deep dive into the IO-Link Safety protocol, I suggest visiting the IO-Link Consortium’s website at io-link.com. In this system/architecture, you have IO-Link Safety Masters, which communicate to the Safety PLCs/Controllers over safety protocols like CIP Safety, PROFIsafe, etc. The ports on the Masters can utilize Pin 4 and Pin 2 as OSSD signals (safety ports), so standard (non-network) safety devices can be connected. Pin 4 can also be used to carry standard IO-Link and IO-Link Safety communication to standard IO-Link devices and IO-Link Safety devices, respectively. This allows for the most versatile safety solution in the market–IO-Link Safety Masters that can accept standard (non-network) safety devices, standard IO-Link devices, and IO-Link Safety devices. Intelligence in the IO-Link Safety devices is now available.

Benefits of IO-Link Safety

    • IO-Link Safety devices are fieldbus neutral: you just need to specify the IO-Link Safety Master to match the Safety PLCs/Controllers protocol.
    • IO-Link Safety Master port versatility: standard (non-network) safety devices, standard IO-Link devices, and IO-Link Safety devices can be connected.
    • Parameter storage: standard IO-Link and IO-Link Safety device’s parameters can be stored for ease of device replacement.
    • Smart IO-Link Safety device data: more data available, like internal temperature, humidity, number of cycles, power consumption, diagnostics, etc.
    • Simplified wiring: IO-Link Safety devices are still connected to the IO-Link Master port with a standard 3 to 4 conductor cable.
    • IIoT fit: IO-Link Safety gives more visibility to upper-level systems like SCADA, allowing safety device-level monitoring.

I am looking forward to seeing how quickly IO-Link Safety will be accepted, with how IO-Link numbers have skyrocketed over the last few years. The future looks great for IO-Link with IO-Link Safety, IO-Link Wireless and in the future, Single-Pair Ethernet (SPE). With all these new capabilities, what application can’t IO-Link support?

How TSN boosts efficiency by setting priorities for network bandwidth

As manufacturers move toward Industry 4.0 and the Industrial Internet of Things (IIoT), common communication platforms are needed to achieve the next level of efficiency boost. Using common communication platforms, like Time-Sensitive Networking (TSN), significantly reduces the burden of separate networks for IT and OT without compromising the separate requirements from both areas of the plant/enterprise.

TSN is the mother of all network protocols. It makes it possible to share the network bandwidth wisely by allocating rules of time sensitivity. For example, industrial motion control related communication, safety communication, general automation control communication (I/O), IT software communications, video surveillance communication, or Industrial vision system communication would need to be configured based on their time sensitivity priority so that the network of switches and communication gateways can effectively manage all the traffic without compromising service offerings.

If you are unfamiliar with TSN, you aren’t alone. Manufacturers are currently in the early adopter phase. User groups of all major industrial networking protocols such as ODVA (CIP and EtherNet/IP), PNO (for PROFINET and PROFISAFE), and CLPA (for CC-Link IE) are working toward incorporating TSN abilities in their respective network protocols. CC-Link IE Field has already released some of the products related to CC-Link IE Field TSN.

With TSN implementation, the current set of industrial protocols do not go away. If a machine uses today’s industrial protocols, it can continue to use that. TSN implementation has some gateway modules that would allow communicating the standard protocols while adding TSN to the facility.

While it would be optimal to have one universal protocol of communication across the plant floor, that is an unlikely scenario. Instead, we will continue to see TSN flavors of different protocols as each protocol has its own benefits of things it does the best. TSN allows for this co-existence of protocols on the same network.

 

What Exactly is Safety Over IO-Link?

Users of IO-Link have long been in search of a solution for implementing the demands for functional safety using IO-Link. As a first step, the only possibility was to turn the actuators off using a separate power supply (Port class “B”, Pins 2, 5), which powers down the entire module. Today there is a better answer: Safety hub with IO-Link!

Automation Pyramid.png

This integrated safety concept is the logical continuation of the IO-Link philosophy. It is the only globally available technology to build on the proven IO-Link standards and profisafe. This means it uses the essential IO-Link benefits such as simple data transport and information exchange, high flexibility and universal applicability for safety signals as well. Safety over IO-Link combines automation and safety and represents efficient safety concepts in one system. Best of all, the functionality of the overall system remains unchanged. Safety is provided nearly as an add-on.

In the center of this safety concept is the new safety hub, which is connected to an available port on an IO-Link master. The safety components are connected to it using M12 standard cable. The safety profisafe signals are then tunneled to the controller through an IO-Link master. This has the advantage of allowing existing infrastructure to still be used without any changes. Parameters are configured centrally through the user interface of the controller.

Safety Hub

The safety hub has four 2-channel safe inputs for collecting safety signals, two safe outputs for turning off safety actuators, and two multi-channel ports for connecting things like safety interlocks which require both input and output signals to be processed simultaneously. The system is TÜV- and PNO-certified and can be used up to PLe/SIL 3. Safety components from all manufacturers can be connected to the safe I/O module.

Like IO-Link in general, Safety over IO-Link is characterized by simple system construction, time-and cost-saving wiring using M12 connectors, reduction in control cabinet volume and leaner system concepts. Virtually any network topology can be simply scaled with Safety over IO-Link, whereby the relative share of automation and safety can be varied as desired. Safety over IO-Link also means unlimited flexibility. Thanks to varying port configuration and simple configuration systems, it can be changed even at the last minute. All of this helps reduce costs. Additional savings come from the simple duplication of (PLC-) projects, prewiring of machine segments and short downtimes made possible by ease of component replacement.

Capture

To learn more about Safety over IO-Link, visit www.balluff.com.