To replace 4 mA to 20 mA or fieldbus communications (Foundation Fieldbus or PROFIBUS PA) with Ethernet-APL in process automation applications, both power and data need to be provided to the sensors and actuators. The distance between field-level devices and control systems in process automation applications has been a significant challenge to existing Industrial Ethernet physical layer technologies being limited to 100 m. With distances of up to 1 km required in process automation applications, combined with the need for very low power and robust field devices suitable for use in Zone 0 (intrinsically safe) applications, a new approach to realize Ethernet physical layer technology for process automation was required. Ethernet-APL is this new approach.
Ethernet-APL is based on 10BASE-T1L physical layer capability of a full-duplex, dc-balanced, point-to-point communication scheme with PAM 3 modulation at a 7.5 MBd symbol rate, 4B3T coding. It supports two amplitude modes, 2.4 V peak up to 1000 m cable and 1.0 V peak at a reduced distance. The 1.0 V peak amplitude mode means that this new physical layer technology can also be used in the environment of explosion-proof systems (Ex) and meet the strict maximum energy restrictions. 10BASE-T1L enables long distance transmission on two-wire technology of both power and data over a shielded, single twisted pair cable.
When it comes to power delivery to field devices, Ethernet-APL can deliver up to 500 mW in Zone 0 applications, compared to that of approximately 36 mW delivered by 4 mA to 20 mA systems today. In nonintrinsically safe applications, up to 60 W of power is possible depending on the cable used. With significantly more power available at the edge of the network, new field devices with enhanced features and functions can be enabled because the power limitations of 4 mA to 20 mA and fieldbus no longer apply. For example, higher performance measurement and enhanced edge processing of data is now possible with this additional power. This will unlock valuable insights about process variables that will now be made accessible via a web server running on the field-level devices (field assets), and which will ultimately drive improvements and optimizations in process flows and asset management.
To exploit the rich dataset containing these valuable new insights, a higher bandwidth communications link is required to deliver the datasets from these new field devices across the process installation to plant-level infrastructure or up to the cloud for processing. Ethernet-APL removes the need for complex, power hungry gateways and enables a converged Ethernet network across the information technology (IT) and operating technology (OT) domains. This converged network delivers a simplified installation, easy device replacement, and faster network commissioning and configuration. This results in faster software updates with simplified root cause analysis and maintenance of field-level devices.