As part of the move to single pair Ethernet in factory automation, Texas Instruments (TI) has developed a physical layer (PHY) capable of 10Mbit/s Ethernet over 1.7 km over a single twisted pair.
The extended cable reach of the DP83TD510E for single pair Ethernet enables the direct replacement of two wire 4-20mA current loops which can run to several km in length and can be daisy-chained for longer reach. The 802.3cg 10BASE-T1L single-pair Ethernet specification cites a minimum range of 200m for 1V signals, and 1km for 2.4V signals. The TI transceiver has a 1.7km range for both voltages.
“A significant architectural effort on the signal processing block enables the 1.7km in both voltage modes,” said Genevieve Vansteeg, marketing manager at TI.
The use of long range single pair Ethernet for fieldbus networks avoids the need for protocol conversion through gateways, she says.
“The key thing is to be able to move all the additional data faster and further without making the system more complex and meet new requirements such as intrinsic safety,” she said. “This can also be used to look at data trends over time for preventative maintenance and to look at ways to optimise the network.”
The DP83TD510E is designed for use in intrinsically safe Ethernet advanced physical layer (APL) systems. Ethernet-APL is an Ethernet specification based on the IEEE 802.3.cg 10BASE-T1L standard and was developed to streamline implementation of Ethernet networking in process automation systems with intrinsic safety requirements.
A key design consideration of intrinsically safe Ethernet-APL systems – especially systems designed for use in hazardous environments with explosive potential – is the ability to reduce Ethernet PHY power levels and temperature during system failure conditions. With a 45mW power consumption and external termination resistors, the DP83TD510E can reduce inrush current and maintain lower operating temperatures when used in long-distance process automation applications, such as field transmitters.
“Another thing that