COVER STORY
The new 10BASE-T1L standard – Has anything changed?
Thomas Brand, Senior Field Applications Engineer, and Thomas Tzscheetzsch, Technical Director EMEA, both at Analog Devices, explain the basics of 10BASE-T1L and discuss the available products for industrial applications
D
ata communication is taking on an ever-greater role not only in the industrial sector but also in process
automation. The previous 4-20mA or fi eldbus applications are reaching their limits due to burgeoning data volumes, and Ethernet is thus crystallising 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 100Mbps or 1000Mbps and thus is a supplement. 10BASE-T1L is becoming standardised, especially in process automation, and has the potential to make sweeping changes in this area. Precisely here, up to now, sensors and actuators have usually been connected via a 4-20mA analogue interface or a fi eldbus. 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, with distances of 200m to 1000m and above being common.
But what exactly is 10BASE-T1L, what
are its advantages, and why is it a new standard?
10BASE-T1L
In the name 10BASE-T1L, 10 references a transmission rate of 10Mbps; BASE refers to baseband signals, which means that only Ethernet signals can be transported over the medium; T is for twisted pair; 1 refers to 1km range; and L is for long range, meaning that segment lengths of 1km and longer are possible. There are still other network technologies, such as 10BASE-2 (thin coaxial cable with a maximum segment length of 185m), 10BASE-5 (thick coaxial cable with a maximum segment length of 500m), 10BASE-F (fi bre optic cable), or 10BASE-36 (broadband coaxial cable
Figure 1: Sample architecture with both conventional and 10BASE-T1L-capable field instruments
with multiple baseband channels and a maximum segment length of 3600m). 10BASE-T1L off ers the possibility of using the existing 2-wire infrastructure to realise line lengths of up to 1000m at a transmission speed of 10Mbps. The physical Ethernet technology is defi ned exclusively in Layer 1 (the bit transmission layer or physical layer) of the Open Systems Interconnection (OSI) model. Above the bit transmission layer, 10BASE-T1L supports common Ethernet protocols such as PROFINET, Modbus, etc., as well as other bus systems, such as BACnet, KNX and LON, commonly used in building management systems; see Table 1.
10BASE-T1L is implemented with the help of a special Ethernet PHY in Layer 1. The Ethernet frames are transmitted between MAC and PHY via the media- independent interface (MII), reduced MII (RMII), or reduced gigabit MII (RGMII). The MAC is defi ned by the Ethernet standard IEEE 802.3 and implemented in the data link layer (Layer 2). The
8 November 2022 | Automation
automationmagazine.co.uk
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