Communication of data between various devices is essential in many aspects of daily living. The proliferation of devices and the dramatic increase in data volumes driven by digitalization and Industry 4.0 are forcing changes in the communication landscape. In this article, get an in-depth look at the 10BASE-T1L standard for industrial 2-wire ethernet, including connectivity, hardware, power, and more.
Introduction
Data communication is taking on an ever-greater role not only in the industrial sector but also in process automation. The previous 4 mA to 20 mA or Fieldbus applications are reaching their limits due to burgeoning data volumes, and Ethernet is thus crystallizing as the communication standard. The standard Ethernet, 4-wire solution has evolved into a 2-wire solution known as 10BASE-T1L, consisting of a single pair of twisted cables or single-pair Ethernet (SPE). Above the physical layer, 10BASE-T1L is compatible with existing Industrial Ethernet technologies with 100 Mbps or 1000 Mbps and thus is a supplement.
10BASE-T1L is becoming standardized especially in process automation and has the potential to effect sweeping changes in this area. Precisely here, up to now, sensors and actuators have usually been connected via a 4 mA to 20 mA analog interface or a Fieldbus. In process automation, unlike in mechanical engineering or plant automation, these sensors and actuators are usually at a distance to the control system or the remote I/O systems. Distances of 200 m to 1000 m and more are common.
What Does 10BASE-T1L Mean?
The name 10BASE-T1L roughly explains its meaning. The Institute of Electrical and Electronics Engineers (IEEE) abbreviations are used here.
The “10” in the medium type references a transmission rate of 10 Mbps. “BASE” refers to baseband signals, which means that only Ethernet signals can be transported over the medium. “T” stands for “twisted pair.” The digit “1” stands for 1 km range. In this case, it is followed by an “L” for “long-range,” meaning that segment lengths of 1 km and more are possible.
With Which Devices and Machines Can 10BASE-T1L Be Used and To What Extent Can the Existing Infrastructure Be Used with It?
10BASE-T1L is designed to replace the 4 mA to 20 mA standardized signal in many, if not most, process automation applications. However, this does not mean that older field instruments connected via 4 mA to 20 mA current loops will have to be replaced with 10BASE-T1L–capable field instruments. These conventional devices can be connected via software configurable I/O (SWIO) modules, while remote I/Os serve as a collection point for connection to the PLC with a 10 Mbps Ethernet uplink.
Software configurable I/O modules have reconfigurable module channels, which allows them to work quickly, easily, and remotely without requiring extensive rewiring. The channels can be configured either as input or output both for currents and voltages, or digital and analog.
In some cases, there is a requirement that both power for the devices and their data be provided via 10BASE-T1L, which is defined as part of the standard. 10BASE-T1L supports two amplitude modes: 2.4 V for cable lengths of up to 1000 m and 1 V for shorter distances up to 200 m. Through the 1.0 V peak-to-peak amplitude mode, this technology can also be used in explosion-protected environments (hazardous areas) and meets the strict maximum energy consumption requirements applicable there.
What Are the Advantages of 10BASE-T1L?
Conventional 4 mA to 20 mA with HART® and fieldbus devices have a limited data bandwidth of just a few kbps. With 10BASE-T1L, speeds of 10 Mbps can be reached. This makes it possible to transmit not only a process value but also additional device parameters such as configuration and parameterization information. In the future, possible software updates for the increasingly complex sensors, as well as fault and network diagnostics such as short circuits on the line to the sensor, will be performed relatively quickly via the data line. Configuration is also easier because gateways and converters are no longer required with 10BASE-T1L. Through the elimination of the gateways, the costs and the complexity of these old installations are greatly reduced, and the data islands created by them are swept away.
In addition, higher powers can be transmitted over the data line. For example, 500 mW in intrinsically safe areas (hazardous areas) and even up to 60 W in non-intrinsically safe areas can be transmitted.
Ethernet standards such as PROFINET, EtherNet/IP, HART-IP, OPC UA, or ModbusTCP, and IoT protocols such as MQTT, can enable the easy and powerful connection of field devices to a cloud.
Does 10BASE-T1L Also Work with Switch Modules?
As with standard Ethernet, with 10BASE-T1L there are bridges that enable coupling of various network segments and devices. Different network topologies can be realized and used to supply power to the connected devices. In process automation, switches are often connected to controllers, HMIs, and the cloud. Switches allow media redundancy in the form of ring topologies for increased availability.
In process automation, the connections to the devices, sensors, and actuators are also called spurs, whereas connections between the switches and running up to the control system fall under the name trunk.
Can I Also Implement the Power Supply to the Devices via the “Two Wires”?
The 10BASE-T1L standard not only offers communication of data from sensors and actuators, but also provides the possibility of supplying them with power via the signal lines. Concretely, 10BASE-T1L can deliver up to 60 W of power in non-intrinsically safe areas. In explosion-protected (intrinsically safe) areas, the power is limited to 500 mW; in this case, the signal amplitude is also reduced from that of standard applications from 2.4 V to 1 V to comply with the strict requirements for maximum energy applicable there. However, as a result, only reduced transmission distances are possible in intrinsically safe areas.
Conclusion
10BASE-T1L provides a relatively robust communication standard for process automation that offers numerous advantages over conventional 4 mA to 20 mA applications, including the possibility of reusing the existing infrastructure.