Mastering the Black Channel

Feb. 29, 2024
Discover what network technologies are best suited to address the need of functional-safety communications in the era of Industry 4.0.

This video is part of the TechXchange: Time for Time-Sensitive Networking.

What you’ll learn:

  • What are the black and white channels?
  • Safety communications solutions for industrial automation.
  • Network technology guidelines for safety of converged networks. 
  • How to provide communication through the black channel, which is more cost-effective and versatile for interconnectivity. 
  • How time-sensitive networking fits into the mix.


The pursuit of seamless and uninterrupted automated operations is paramount for forward-looking companies on their digital transformation journey, especially when it comes to functional-safety communications. 

Typically designed as isolated networks, safety communications solutions add to the very complexity that industrial automation specialists prefer to avoid, particularly as systems become more complex and interconnected to create smart factories. Using a robust network technology that can support safety applications in converged frameworks can be a game-changer.

Safety communications safeguard both equipment and users by detecting abnormal situations, preventing hazards, and triggering safety measures—when necessary—as well as provide a mechanism to guarantee continuous connectivity. Thus, they’re a must for industrial environments and many other applications, such as railway systems.

Typically, industrial automation specialists have been driving reliability in safety communications by setting up purpose-built, redundant networks. These comply with specific safety regulations, e.g., IEC 61508 SIL standards, and don’t support the transfer of any other type of traffic. In these instances, the channel is well defined and known as a “white channel.”

The Perks of Joining the Dark Side

While this solution is highly effective, it contributes to expanding wiring requirements, ultimately increasing capital and running costs while making network infrastructures and architectures more intricate.

What’s more, that approach could be challenging to implement for complex safety situations, such as systems that interact with robotic safety zones or with multiple detection safety devices. Finally, siloing safety communication directly clashes with the concept of highly interconnected facilities as required by digital manufacturing applications.

Recently, “black channel” approaches have become more popular to overcome these issues and eliminate the need for separate, safety-specific networks. Within such a framework, machine safety communications coexist on the same wire with non-safe data, e.g., cyclic and acyclic traffic.

This can occur with an overlaid protocol that adds an extra safety layer between the last layer of the OSI model and the application, in line with IEC 62280 standard. As the data being sent from one safety device to another is secured and transmitted by an unknown communication channel, mechanisms to identify and eliminate possible errors are set in place, ensuring the integrity of data-transmission operations. Ultimately, the black channel can enable more cost-effective, versatile, and flexible convergent architectures that support interconnectivity.

It's Not Black Magic

To further improve the effectiveness of black channel setups, it’s highly beneficial to leverage a network technology that can offer deterministic performance. When it comes to industrial Ethernet, this means favoring solutions that include time-sensitive networking (TSN), which improves the determinism of standard Ethernet.

Not withstanding, offering maximum bandwidth, such as 1 Gb, helps users make sure that their convergence networks can transfer large volumes of data. An example of such a network technology is CC-Link IE TSN open industrial gigabit Ethernet with TSN functions.

Finally, when implementing networks that can support black channel methods, it’s important to select solutions that maximize openness, interoperability, coexistence, and accessibility. In effect, any proprietary safety option can limit machine builders, automation system integrators, and end users in the choice of suitable hardware, software, and other tools.

A key industrial automation solution that can address these challenges and drive the implementation of black channel methods for effective and convergent safety communications are specialized PLCs that offer multiple safety module options. They provide the performance and integrity levels of safety PLCs without the need for a separate controller.

Specifically, specialists are now enabled to create applications that comply with ISO 13849-1 PL e and IEC 61508 SIL 3 standards. The safety modules currently available include options for TSN and common industrial protocol (CIP) safety black channel communications.

Ideally, programmers will find that market solution is able to support two different yet coexisting protocols, while delivering deterministic performance, thanks to key TSN functions. PLC modules can help companies set up the safety communication solutions that best address their need while leaving room for future modifications.

Compliance with TSN protocols allows for communication with a broad and ever-expanding number of compatible industrial-automation components from a variety of vendors, driving flexibility and interconnectivity. Ultimately, by specifying robust PLCs and modules, companies can drive the setup of effective, reliable safety communications based on black channel principles.

Check out more videos/articles in the TechXchange: Time for Time-Sensitive Networking.

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