Ethernet Bypass Switch

Abstract

An ASIC solution is studied and designed to solve a possible communication
interruption due to power failures of automation servers connected in serial topologies.
This installation method is widely employed in industrial Ethernet networks.
However, it presents a disadvantage, a failure in a network’s node isolates the following nodes until maintenance repairs it. The solution studied during this thesis bypasses the damaged node allowing the communication between the rest of the
chain.
The circuit proposed consists on CMOS switches powered up by harvesting
energy from the Ethernet communication lines. An analysis of the transmission
data signals was conducted in order to model the application environment and
determine the requirements for the project. Simulations were performed with
schematics and layout in order to verify the concept. A solution based on an
ASIC was proven to be feasible.
This research was conducted in collaboration with Schneider Electric.

Popular Abstract

Automation servers are tools that execute a plurality of tasks, more precisely
in the task management domain. Being automated means this process does not
require human intervention to function.
These units communicate through Ethernet data signals. Ethernet is the most
popular way for a local area network (LAN) or wide area network (WAN) to
connect to devices and servers that require a connection to the INTERNET[2].
The data signals follow the Ethernet protocol, which presents distinct characteristics on transmission methods, such as speed, amplitude voltage and signal encoding.
One of the most used installation methods for the automation servers is the
star topology. It consists on having every server directly connected to the central
hub. In this manner, the central hub can communicate directly to the desired
device, without passing through intermediates. However, it requires an important
amount of cabling to be placed. In order to reduce costs, industrial applications
employ a different topology.
The common practice in automation buildings is to implement these servers
in a daisy chain topology. This means that they are all connected in series, being
placed one after the other and only physically connected to a directly preceding
or following device.
The installation method mentioned above results in a possible communication
break in case one of the servers in the network chain malfunctions. This is attributed to the fact that if one node in the chain is inoperable, the data signals experience a blockage, compromising the communication between the network hub and the servers.
The goal of this project is to propose a solution able to maintain the link path
between units even if one of them fails. To achieve this, research on the Ethernet
standard specifications has to be performed in order to determine the requirements
that need to be met.
These requirements were defined based on research and experiments conducted
at Schneider Electric, using an already existing device as a reference automation
server.
The proposed solution consists on an integrated circuit which function is to
isolate the damaged node and operate as a bridge between the input and output
signals traversing this point.
We wish to present a chip able to extract energy directly from the communication
wires, therefore not requiring any external power sources. This approach
involves more research since energy harvesting from communication lines is not a
subject that has been broadly explored, even in the Academic domain. A complete
view of the design schematics can be found in figure A.2 in the Appendix section.
The nature of the Ethernet transmission signals and the different modes of operation also impose some extra issues regarding the performance of the integrated
circuit proposed here. For instance, when the system is powered on during the
first installation, if a unit is found to be in failure mode, the default set up of the server would not provide strong signals for the IC to become active and bypass
the signals. Issues such as this one are also addressed in this thesis.

• author: Rau, Lais and Benages, Sergio
• supervisor: Henrik Sjöland
• organization: Department of Electrical and Information Technology
• course: EITM02 20181
• year: 2018
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: integrated circuit, ethernet, power failure, switch, energy harvesting
• publication/series: Master Thesis Written Report
• report number: LU/LTH-EIT 2018-631
• language: English
• id: 8948692
• date added to LUP: 2018-06-18 14:26:38
• date last changed: 2018-06-18 14:26:38