The Problem with Protocol Standards and the Solution

Profinet, EtherNet/IP, EtherCAT, CC-Link, Mudbus, OPC UA are common in industrial automation. SNMP, REST, SMTP, POP, HTTP, FTP, ODBC, OLE-DB and OPC UA (again) are protocols common in the IT space. Over standard Ethernet, these protocols can co-exist and share the bandwidth available to them. With gigabit bandwidth being the latest standard, things will work relatively well. 

 

However, when applications require a higher level of determinism and reliability, users are forced to isolate communications to separate networks, typically the OT (operations technology) network and the IT network. Doing so raises costs due to more complex architectures to create and maintain, and communications become more limited as devices are no longer available for all uses. 

 

Multiple protocols will always exist. They were developed for different purposes and are sometimes specific to vendors. Many vendor protocols have been made available to the world as international standards, managed by non-profit organizations, to better enable industry and global adoption. Examples include PI International, ODVA, CLPA (CC-Link Partner Association) and the OPC Foundation. The fact is, protocols will need to coexist going forward as each delivers a unique set of features and benefits, and there will likely never be one all-encompassing solution.

 

A great example of a common problem faced when isolating networks is the loss of SNMP (simple network management protocol) management from IT to OT networks. SNMP enables IT networks to connect with and interrogate devices on a network. A simple ping can measure response time to a device. SNMP can query operating parameters, firmware revisions and more, dependent on the features supported by the device vendor. SNMP has become ubiquitous since its inception in 1988. 

 

But with standard Ethernet, there is no way to prioritize one protocol over another and hence, the desire for a deterministic (time sensitive and optimized performance communication scenario) requires a planned and known communications strategy. Previously, that has only been possible with an isolated network and managed communications.

 

In 2016, a new set of Ethernet standards were released, including features for TSN (time sensitive networking). The new standard includes several features that are key to industrial automation. They include: 

 

The ability to take one protocol, with time sensitive operation, and let that coexist with other less time-critical protocols is a game changer for industry. We are still early in the adoption cycle of TSN and one company, Mitsubishi Electric, has adopted the TSN standards and is delivering products in conjunction with a number of device vendors. This new ecosystem of TSN solutions is enabling a new generation of machines to come to market.

 

Industrial machines often have motion control requirements for applications when a time critical function has to be performed over a device communications network. Usually, there is only one real-time and critical function to be performed, meaning that using one TSN-based protocol is a reasonable thing to consider. With TSN, the less critical communications for machine status, operator interface and data access functions can now co-exist on the same network with the motion control communications. 

 

This means that network architectures can now be simplified while device access for control, management and data collection can be maximized. The result is the ability to use a single network that is more cost effective and enhances the ability for troubleshooting. This is possible by using network switches with TSN support, which enable the functional isolation of network legs to maximize bandwidth while still enabling access to all devices for management or information purposes.

 

Vendor products with Ethernet TSN support have been on the market since 2018 and are paving the way for a new class of higher performance and more information-centric machines to be built. A directory of these products can be found on the CLPA (CC-Link Partner Association) website at www.CC-Link.org is the non-profit, global organization that manages adopters of the CC-Link IE TSN protocol that supports Ethernet time sensitive networking.