Progress is also being made on Ethernet networking in process plants with explosive atmospheres, although this area remains the domain of highly specialized experts due to its extremely complex requirements. R. STAHL, a leading global supplier of explosion-protected components and systems, has therefore spent more than ten years focusing on solutions for ex-protected Ethernet-based process plant digitalization. This special manufacturer’s existing portfolio, which is being continuously developed and enhanced, includes network components and equipment that require a consistent Ethernet infrastructure in Zone 1 and Zone 2 or in Class I, Div. 1 and 2: For safe data transmission in hazardous areas, media converters and switches for optical cables can be used for transfer rates of 100 Mbit/s and distances of up to 30 km.
The “op is” type of protection for inherently safe optical radiation according to IEC 60079-28 ensures that ignitable optical energy potential in the fiber optics will not exceed a dangerous level, even under fault conditions. This means that extensions, modifications, and maintenance work can be performed during ongoing operation and under hazardous conditions, just like “i” intrinsic safety according to IEC 60079-11. Alternatively, “op pr” fiber optic installations, which are similar to the “e” type of protection, are also available. With “Ex op pr”-certified splice boxes, R. STAHL enables convenient patching of protected optical radiation in Zone 1.
If CAT copper cables are used in hazardous areas, many users are currently still set on using increased safety type of protection “e”. Since the use of standard Ethernet components in Zone 1 is not possible without any additional equipment, R. STAHL offers certified “Ex e” terminals for up to 1 GBit/s. For intrinsically safe sensor/actuator networking with the control system, the explosion protection specialist offers the IS1+ Remote I/O system – a proven in use multitalented communication system that works with PROFINET, PROFIBUS DP, Modbus TCP and EtherNet/IP. The connection in Zone 1 is established using “op is” fibre optics. In Zone 2, users also have the option to use more cost-effective CAT-5 copper cable with “ec” type of protection for transmission paths measuring up to 100 m.
The digital data from connected HART field devices is transmitted parallel to the process control via the Ethernet network in the second channel and can be evaluated using either the “classic” method using FDT/DTM or the “modern” method using OPC UA mechanisms. To drive the development of internationally accepted intrinsically safe Ethernet concepts, R. STAHL actively participates in the Ethernet Advanced Physical Layer (APL) project and the Intrinsically Safe Ethernet Working Group. While the Ethernet-APL project is designing an intrinsically 2-wire-based Ethernet solution for transfer rates of 10 MBit/s and transfer paths up to 1000 m that also includes an intrinsically safe field device supply, the Intrinsically Safe Ethernet Working Group is creating a standard for intrinsically safe 4-wire Ethernet transmission at a speed of 100 MBit/s.
Specifications and initial products are expected to be released in 2021. What’s more, as an active member of NAMUR Open Architecture (NOA) and the Open Process AutomationTM Forum (OPAF), R. STAHL is making an active contribution to the continued development and standardization of digitalization concepts.