Feature: Interconnections


T e launch of Ethernet-APL in 2021 was a game changer for suppliers of fi eld devices in the process industry. T e required features were specifi ed by the involved industrial user groups (FieldComm Group, ODVA, PI and the OPC Foundation), including conformance test specifi cations. T us, at the SPS Fair in November 2023, the fi rst certifi ed products were presented to the public.


Table 1: IEEE SPE defi nitions


due to the experiences with Multi-Pair Ethernet in IT systems.


SPE today IEEE 802.3cg defi nes not only the 10BASE- T1L segment, but also an associated remote powering scheme through Power over Data Line (PoDL) classes 10-15, which complement classes 0-9 that were defi ned in 802.3bu for use with IEEE 802.3bw or IEEE 802.3bp, respectively. T e Ethernet Alliance is referring to


classes 10-15 as “Single-Pair Power over Ethernet (SPoE)”. T e actual power class used to supply a powered device (PD) from power source equipment (PSE) is determined via the serial communication classifi cation protocol (SCCP). It’s an optional feature, defi ned in IEEE 802.3bu and reused for the additional classes defi ned in IEEE 802.3cg. Ethernet-APL does not use SPoE, as


the power levels exceed the intrinsic safety limits. However, for non-hazardous environments, 10BASE-T1L and SPoE provide the fundamental requirements for equipping sensors and actuators with Ethernet communication capabilities and remote power. T e bandwidth of 10Mb/s even allows


for connecting IP cameras, with a typical resolution of 2MP (1920p x 1080p) and a frame rate of 20FPS, which with a typical codec (e.g., H.264) requires a bandwidth of 1.65-4.31Mb/s. Power demands beyond what’s specifi ed in the IEEE 802.3cg can be realised


through a hybrid cable. But, sensor manufacturers are hesitant to incorporate SPE into their devices for various reasons. Most notably, the adoption of SPE by industrial user groups such as PROFIBUS & PROFINET International (PI) and ODVA isn’t yet complete. T e defi nition of preferred non-hybrid connectors is pending, which delays market adoption and maintains high integration costs.


SPE in switches and connectors T e launch of Ethernet-APL fi eld devices was accompanied by the fi rst fi eld switches, which support a compact star topology, one of the two fundamental Ethernet-APL confi gurations. Naturally, the idea to use Ethernet-


APL fi eld devices with SPE switches followed. Ethernet-APL, however, uses a remote powering scheme, which meets the requirements of the port profi le specifi cation in IEC TS 63444. T is scheme does not use the optional SCCP feature, which is why initiatives are now under way to defi ne a combined detection and classifi cation scheme:


BELDEN’S BEETLE


The first SPE switches are compact and cost- efficient.


Belden’s Lumberg Automation Lite Managed SPE Switch (BEETLE) features eight 10BASE-T1L downlink ports supporting all 24V SPoE classes up to class 12 with 8.4W. It comes with an IP40 housing and M8 connectors according to IEC 63171-6.


When it comes to switching capabilities, the BEETLE offers VLAN according to IEEE 802.3Q and prioritisation features QoS/IEEE 802.3D/p and TOS/DSCP. Furthermore, it provides LLDP (IEEE 802.1AB) and RSTP (IEEE 802.1w), unknown multicast filtering, egress interface shaping and ingress storm protection. These can all be configured with the embedded web server.


Moreover, the BEETLE supports OPC UA to allow access to operational and process data from higher-level IT systems/cloud applications.


www.electronicsworld.co.uk July/August 2024 27


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