INDUSTRY 4.0 u ANALOG DEVICES
Table 1. Overview of the OSI model with the protocols and bus systems found in it OSI Model Layer
BACnet Host Layers
7 | Application 6 | Presentation 5 | Session 4 | Transport
Media Layers
3 | Network 2 | Data Link 1 | Physical
BACnet application layer — —
UDP (BACnet/IP), TCP (BACnet/SC)
BACnet network layer Modbus Modbus KNX TCP IP, ARP, RARP ISO 8802 (IEEE 802.3) Shielded or unshielded single twisted pair (IEEE 802.3cg) Sample architecture with both conventional and 10BASE-T1L-capable field instruments]
via the media-independent interface (MII), reduced MII (RMII), or reduced gigabit MII (RGMII). The MAC is defined by the Ethernet standard IEEE 802.3 and implemented in the data link layer (Layer 2). The PHY forms the physical interface and is responsible for coding and decoding the data between the transmission medium and the digital system.
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 4mA to 20mA standardised signal in many, if not most, process automation applications. However, this does not mean that older field instruments connected via 4mA to 20mA 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 10Mbps Ethernet uplink. Software configurable I/O modules have reconfigurable module channels which allows
24 June 2023 Irish Manufacturing
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 analogue. 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. Figure 1 shows an example of a mix of conventional field instruments connected via a 4mA to 20mA current loop and new 10BASE-T1L- capable field instruments. 10BASE-T1L supports two amplitude modes:
2.4V for cable lengths of up to 1000m and 1V for shorter distances up to 200m. Through the 1.0V 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. An industry consortium has specified the advanced physical layer (APL), which builds on the 10BASE-T1L standard, defining intrinsically safe operation for process automation. Ethernet-APL likewise enables the transition to seamless process automation installations with field-to-cloud connections, including areas with potentially explosive atmospheres for installations in
the food and beverage, pharmaceutical, and oil and gas industries. Furthermore, APL also defines the power provisioning classes over the single twisted pair lines.
No concrete transmission medium (cable) is defined with 10BASE-T1L. Only the requirements for return loss and insertion loss of the cables are specified. Fieldbus Type A cables are the cables of choice. This allows the reuse of existing PROFIBUS or Foundation Fieldbus cabling. 10BASE-T1L works with a balanced pair of conductors over a cable length of up to 1000m without any problems. However, in noisy industrial environments, a shielded cable like Type A cable is required – using connectors, screw terminals, or punch-down blocks. Some 10BASE-T1L switch chips have integrated diagnostics functions that check the signal quality over the cables. 10BASE-T1L is thus a very robust communication technology - even a mix-up of the wires does not pose a problem.
WHAT ARE THE ADVANTAGES OF 10BASE-T1L? Conventional 4mA to 20mA with HART and fieldbus devices have a limited data bandwidth of just a few kbps. With 10BASE-T1L, speeds of
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