Patent Description:
In-vehicle network (IVN) buses, such as CAN (Controller Area Network), CAN FD (CAN with Flexible Data-Rate), LIN (Local Interconnect Network), FlexRay, Ethernet based network buses, and other types, can be used for communications within vehicles. For example, controller area network (CAN) bus is a message-based communications bus protocol that is often used within automobiles. It will be appreciated that CAN networks also have application outside of the field of automobiles. A CAN bus network may include multiple bus devices, so called nodes or electronic control units (ECUs), such as an engine control module (ECM), a power train control module (PCM), airbags, antilock brakes, cruise control, electric power steering, audio systems, windows, doors, mirror adjustment, battery and recharging systems for hybrid/electric cars, and many more. The CAN bus protocol is used to enable communications between the various bus devices. The data link layer of the CAN protocol is standardized as International Standards Organization (ISO) <NUM>-<NUM>:<NUM>. CAN Flexible Data-Rate or "CAN FD," which is an extension of the standardized CAN data link layer protocol and is meanwhile integrated into the ISO11898-<NUM>:<NUM> standard, can provide higher data rates. The standardized CAN data link layer protocol is being further extended to provide even higher data rates. A further extension, referred to as CAN XL, with a new level scheme allowing even higher data rates is in the definition phase discussed under CiA610 (CAN in Automation) and is moving towards standardization in the form of either a further update of the existing ISO11898 standards or a new standard.

<CIT> relates to fault tolerant communication systems.

<CIT> relates to methods and systems for providing fault isolation in a controller area network.

Example <FIG> shows a communication bus based network <NUM> with a plurality of nodes <NUM>-<NUM> coupled to a common communication bus. The bus system <NUM> comprises a Controller Area Network, CAN, in this example. The plurality of nodes or ECUs (Electronic Control Units) <NUM>-<NUM> are connected to the same CAN bus wires <NUM> comprising a first wire <NUM>, known as CANH, and a second wire <NUM>, known as CANL. The nodes <NUM>-<NUM> may comprise nodes that implement Classical CAN, CAN FD nodes that implement the CAN FD protocol or CAN XL nodes that implement the new CAN XL protocol.

Example <FIG> shows one of the nodes <NUM>-<NUM> in more detail. A node mainly comprises a CAN controller <NUM>, such as a microcontroller, that implements the CAN, CAN FD or CAN XL protocol such as by using an embedded CAN, CAN FD or CAN XL protocol controller <NUM>. The CAN controller <NUM> may be known as a host. The controller <NUM> and, more particularly, the protocol controller <NUM> is connected to the CAN bus <NUM> via a CAN transceiver <NUM>. The CAN controller <NUM> is connected to the CAN transceiver <NUM> through two interface connections called TXD (Transmit Data) <NUM> and RXD (Receive Data) <NUM>. The controller may therefore have a transmit output terminal that couples with a transmit input terminal of the CAN transceiver <NUM>. Likewise, the CAN transceiver <NUM> may have a receive output terminal that couples with a receive input terminal of the CAN controller <NUM>.

The examples described below relate to an apparatus that, in one or more examples, may comprise the CAN transceiver <NUM>. However, it will be appreciated that the functionality of the apparatus described may be provided at least in part by the CAN transceiver <NUM>. It will also be appreciated that while the example embodiments are described in the context of CAN, the apparatus may have wider application to other bus based networks.

The apparatus or transceiver <NUM> includes a transceiver arrangement <NUM> configured to generate differential signalling at the first terminal <NUM> and the second terminal <NUM> according to a communication scheme, i.e. the CAN protocol in this example. The transceiver arrangement <NUM> is also configured to receive differential signalling from the first terminal <NUM> and second terminal <NUM> from the communication bus <NUM> according to the communication scheme. As will be familiar to those skilled in the art, the communication scheme defines one or more details of the voltage, timing and encoding of the signals that are to be transmitted on and received from the bus <NUM>. In the present example, the communication scheme defines at least the voltage to be used to provide said differential signalling.

In more detail, the transceiver arrangement <NUM> may be configured to convert transmit data, comprising a digital bit stream on TXD <NUM>, into analogue, differential, signalling on the bus wires <NUM> using a transmitter module <NUM>. The transceiver arrangement <NUM> may also be used to convert analogue signalling from the bus <NUM> into receive data comprising a digital output signal or bit stream by a receiver module <NUM> for providing to the RXD connection <NUM>. The transmitter module <NUM> is thus configured to convert the transmit data into dominant bit and recessive bit differential signals for the bus <NUM>. The receiver module <NUM> is thus configured to receive the differential signals from the bus <NUM> and determine the presence of either a dominant bit or a recessive bit and generate the receive data based thereon. The transceiver <NUM> comprises a first terminal <NUM> configured to couple the transceiver <NUM> to a first bus wire <NUM> of the communication bus <NUM> and a second terminal <NUM> configured to couple the transceiver <NUM> to the second bus wire <NUM> of the communication bus <NUM>.

In general, the CAN transceiver <NUM> and the transceiver arrangement <NUM> thereof comprises an interface device to the network bus and the CAN controller comprises a controller that is configured to transmit data to and receive data from the network via the interface device.

The CAN transceiver <NUM> is known as such because it has the purpose of acting as a transceiver for the CAN controller <NUM> and, as mentioned, the transceiver arrangement <NUM> provides this functionality. However, it will be appreciated by those skilled in the art that current CAN transceivers <NUM> may comprise other functionality in addition to the transceiver arrangement <NUM>, as will be described in more detail later.

<FIG> shows an example of the differential signals on the bus <NUM>. The axis <NUM> shows voltage of the CANH and CANL wires <NUM>, <NUM>. The axis <NUM> shows time. During a first time period <NUM> a recessive bit (representing logic "<NUM>") is present on the bus <NUM>. Thus, the voltage level of CANH and CANL are both at ~<NUM>. 5V such that there is no differential signal between the CANH and CANL wires. During second time period <NUM>, a transceiver <NUM> of one of the nodes <NUM>-<NUM> drives the CANH wire <NUM> to a high voltage level <NUM> and the CANL wire <NUM> to a low voltage level <NUM> such that a differential voltage signal <NUM> between the CANH and CANL wires, referred to as a dominant voltage (representing logic "<NUM>"), is provided. The high voltage level at <NUM> is typically around <NUM> V, while the low voltage level at <NUM> is typically around <NUM> V. The CAN protocol or, more generally, the communication scheme defines the use of these voltages to represent the data transmitted and received from the bus <NUM>.

Errors or physical faults can occur in the CAN bus system <NUM> that can disrupt communication. For example, a fault may occur in the transceiver <NUM> or the communication bus <NUM>.

In some instances the fault may prevent transmission or receipt of signals over one of the CANH <NUM> and CANL <NUM> wires. Thus, the other of the CANH <NUM> and CANL <NUM> wires may not have a fault. In such a circumstance, it is known for the nodes <NUM>-<NUM> to be configured to change to communicating by transmitting and receiving signals using the single, fault-free, bus wire <NUM>, <NUM> of the bus <NUM> when a fault occurs that prevents the use of the usual differential signals, shown in example <FIG>.

There are numerous methods known to those skilled in the art to identify when such faults occur. The examples that follow relate to how to react when such a fault occurs.

It has been found that in some examples, a transition to the intended single-ended communication mode can be difficult. After one of the nodes <NUM>-<NUM> has detected a fault, the communication mode for that one node is changed to single-ended communication, which means communication takes place on one of the CANH and CANL wires <NUM>, <NUM>. A difficulty may be present in that all nodes should similarly and independently identify the occurrence of the faults and thereby switch to the single-ended communication mode or the change in communication mode needs to be reliably detected by all other nodes <NUM>-<NUM> in the network. It is not easy to ensure that under all possible failures, in any network topology, that all nodes <NUM>-<NUM> always detect the change in the communication mode reliably and transition accordingly to the intended single-ended communication mode at the same time.

The apparatus <NUM> or, in this example, the CAN transceiver <NUM> is configured to act in response to a fault detection signal from a fault determination device <NUM>. In the present example, the fault detection device <NUM> is part of the apparatus <NUM> but that need not be the case. In other examples, the apparatus <NUM> is configured to receive the fault detection signal from a different apparatus, such as the controller <NUM>.

In one or more examples, the fault detection signal is a signal that is internal to the apparatus <NUM> or internal to the node <NUM>-<NUM> of which the apparatus <NUM> forms part. Accordingly, it may not be a signal that is provided to or received from the communication bus <NUM>.

The fault detection signal is indicative of the occurrence of a fault in at least the communication bus <NUM> and one or more connections, including terminals <NUM> and <NUM> between the apparatus <NUM> and the communication bus <NUM>. The operation of the fault determination device <NUM> is not the focus of this application and it may use conventional methods to determine when a fault occurs. However, in summary, the fault detection device <NUM> may be configured to detect faults in one or more of the communication bus, the electrical connections that couple the apparatus <NUM> to the bus <NUM>, the electrical connection(s) that couple that apparatus to the controller <NUM> and the electrical connection(s) in one or more network nodes <NUM>-<NUM>. The possible faults that may have occurred to cause the generation of the fault detection signal are described below. However, the occurrence of the fault, whichever way it is detected, is signalled to the apparatus <NUM> by the fault detection signal.

As a non-exhaustive list, there may be one or more of a fault in the supply of power to the transceiver <NUM>; a fault in an internal bias current in the transceiver <NUM>; a fault in circuitry of the transmitter module <NUM>; a fault in the circuitry of the receiver module <NUM>; or a fault in the input/output buffers to the microcontroller <NUM>, <NUM>.

In other examples, there may be a fault in the wiring harness, that is the unshielded twisted pair of wires comprising CANH <NUM> and CANL <NUM>. As a non-exhaustive list, there may be one or more of an: open wire or intermittent open wire on CANH or CANL; open connection contact or intermittent open connection contact at CANH or CANL; open solder joint contact or intermittent open solder joint contact at CANH or CANL; open or intermittently open solder joint contact at transmit-output terminal to TXD or receive-input from RXD at the microcontroller <NUM>; and open or intermittently open solder joint contact at a transmit-input terminal from TXD <NUM> or receive-output terminal to RXD <NUM> at the transceiver <NUM>.

In other examples, there may comprise a fault in the transceiver <NUM> to microcontroller <NUM> connection <NUM>, <NUM> or a fault in the transceiver <NUM> connection to the wiring harness or bus <NUM>, such as at terminals <NUM>, <NUM> or in the stub that couples to a main part of the bus.

To summarize, the fault detection signal may be indicative of a fault comprising at least one of a physical break in one of said first and second bus wires <NUM>, <NUM> of the communication bus <NUM> and a break in the one or more connections between the apparatus <NUM> and the communication bus <NUM>.

The apparatus <NUM>, in response to the fault detection signal, is configured to transmit a reconfiguration signal for said one or more other network nodes <NUM>-<NUM> coupled to the communication bus <NUM>. The reconfiguration signal may be intended for all nodes coupled to the bus <NUM>. The reconfiguration signal may be intended for all nodes coupled to the bus <NUM> that have the functionality or circuitry configured to detect it.

The reconfiguration signal is provided for transmission via at least one of said first terminal <NUM> and said second terminal <NUM>. The reconfiguration signal may be provided to both terminals <NUM> or <NUM>, i.e. the same signal transmitted to both terminals. In other examples, the reconfiguration signal is provided for transmission via the one of the first bus wire <NUM> and the second bus wire <NUM> that does not have the fault indicated by the fault detection signal. Thus, the fault detection signal may be indicative of which of the first bus wire <NUM> and the second bus wire <NUM> has been affected by the fault or which bus wire <NUM>, <NUM> is in working order. Accordingly, the apparatus <NUM> may be configured to use that information to transmit the reconfiguration signal via the first or the second terminal <NUM>, <NUM> such that it is conveyed by the working bus wire <NUM>, <NUM>.

In one or more examples, the reconfiguration signal is distinguishable by the one or more nodes <NUM>-<NUM> from the differential signalling normally present on the bus <NUM> by one or more signal properties that differ from those defined in the communication scheme or protocol for the differential signalling. In CAN, the CAN protocol defines the bit time and the voltages to provide to the bus wires <NUM>, <NUM>. In the present example, at least part of the reconfiguration signal has a high-voltage-level comprising a voltage higher than that defined in the communication scheme for said differential signalling, which may make the reconfiguration signal readily identifiable by detection circuitry of the one or more nodes <NUM>-<NUM>. Thus, the communication scheme may define one or more voltages to be present on the first bus wire <NUM> or CANH as part of generation of the differential signalling. The high-voltage-level of the reconfiguration signal may be higher than the highest of those one or more voltages defined for the first bus wire <NUM> or CANH. Likewise, the communication scheme may define one or more voltages to be present on the second bus wire <NUM> or CANL as part of generation of the differential signalling. The high-voltage-level of the reconfiguration signal may be higher than the highest of those one or more voltages defined for the second bus wire <NUM> or CANL.

In the present example, the reconfiguration signal is configured to cause the one or more network nodes to provide for switching from use of differential signalling to single-ended signalling using only one of the first bus wire <NUM> and the second bus wire <NUM>. Thus, the reconfiguration signal may provide an instruction that achieves the synchronized switching of the signalling method of the nodes to provide a transition between a bus system <NUM> that uses differential signalling to one that uses single-ended signalling. It will be appreciated that by "synchronized" we mean not strictly at exactly the same time but sufficiently close in time that subsequent single-ended communication will be received successfully by all of the nodes <NUM>-<NUM> that react to the reconfiguration signal. Thus, compared to each node <NUM>-<NUM> being configured to determine independently the switch from differential signalling to single-ended signalling, the use of the reconfiguration signal may, in one or more examples, provide for improved network reliability.

In one or more examples, the reconfiguration signal may be configured to achieve other actions at the one or more other nodes <NUM>-<NUM>.

In the present example, the generation of the reconfiguration signal is provided by a reconfiguration module <NUM> of the apparatus <NUM>. The reconfiguration module <NUM> may be configured to control the transceiver arrangement <NUM> to cause it to transmit the reconfiguration signal to the bus <NUM>, as required.

Each node <NUM>-<NUM>, including the apparatus <NUM>, may thus provide a differential communication mode in which the transceiver arrangement <NUM> is configured to transmit and receive the differential signalling, and a single-ended communication mode in which the transceiver arrangement <NUM> is configured to transmit via a single one (the one without the fault) of the first terminal <NUM> and the second terminal <NUM> relative to a reference voltage, such as ground. The apparatus <NUM> or reconfiguration module <NUM> thereof may thus be configured to switch from the differential communication mode to the single-ended communication mode in response to said fault detection signal. The reconfiguration module <NUM> may be configured to provide corresponding signalling to the transceiver arrangement <NUM> to cause the change in the communication mode.

Example <FIG> summarizes the operation of the apparatus <NUM> or the fault detection module <NUM> thereof. Step <NUM> represents the apparatus <NUM> being configured to transmit signalling and/or receive signalling in the differential communication mode, which may comprise the default mode for such an apparatus <NUM>. Step <NUM> comprises a decision block which comprises determining if the fault detection signal has been received, which may be considered equivalent to detecting if a fault has occurred. If the answer is "no" then the method returns to step <NUM>. If the answer is "yes" then the method proceeds to step <NUM>, which comprises transmitting the reconfiguration signal to all other nodes coupled to the communication bus <NUM>, at least via the working bus wire <NUM>, <NUM>. Step <NUM> represents the nodes <NUM>-<NUM> (i.e. all those nodes other than the node that sent the reconfiguration signal) reconfiguring themselves to adopt the single-ended communication mode. Communication between the nodes <NUM>-<NUM> may then continue with the nodes collectively in the single-ended communication mode.

In one or more examples, the reconfiguration signal may be configured to prompt the other nodes coupled to the communication bus <NUM> to switch to single-ended communication mode but it may be left to the other nodes (or transceivers <NUM> thereof) to determine which of the bus wires <NUM>, <NUM> to use in said single-ended communication mode. In one or more other examples, the reconfiguration signal may contain information that signals to the other nodes <NUM>-<NUM> which of the bus wires <NUM>, <NUM> to use in said single-ended communication mode.

<FIG> show two examples of the form of the reconfiguration signal. Example <FIG> shows the reconfiguration signal having a first signal form <NUM>. Example <FIG> shows the reconfiguration signal having a different, second signal form <NUM>. By using different signal forms, the nodes <NUM>-<NUM> that receive the reconfiguration signal (or, more particularly, the transceivers <NUM> thereof) may be informed of which of the bus wires to use for the single-ended communication. Thus, the first signal form <NUM> may be configured to cause the one or more network nodes <NUM>-<NUM> to reconfigure to a single-ended signalling mode using only said first bus wire <NUM>. The second signal form <NUM> may be configured to cause the one or more network nodes to reconfigure to use a single-ended signalling mode using only said second bus wire <NUM>. It will be appreciated that the signal forms are for example only and they could signal the use of the other bus wire in other embodiments to that set out above.

Examples <FIG> show the voltage of the reconfiguration signal on the vertical axis and time on the horizontal axis.

Looking first at <FIG>, the reconfiguration signal of the first form <NUM> comprises a first period <NUM> in which the apparatus <NUM> provides the reconfiguration signal having a high-voltage-level <NUM>. The first period <NUM> may comprise <NUM> microseconds, as an example only. During a directly subsequent second period <NUM>, the reconfiguration signal is provided with a lower, positive second voltage <NUM>. The second period <NUM> may comprise <NUM> microseconds, as an example only. During a directly subsequent third period <NUM>, the reconfiguration signal is provided at the high-voltage-level <NUM> once again. The third period <NUM> may comprise <NUM> microseconds, as an example only.

Looking now at <FIG>, the reconfiguration signal of the second form <NUM> comprises a first period <NUM> in which the apparatus <NUM> provides the reconfiguration signal having the high-voltage-level <NUM>, same as voltage level <NUM>. The first period <NUM> may comprise <NUM> microseconds, as an example only. Thus, the first period <NUM> is shorter than the first period <NUM>. The duration for which the reconfiguration signal <NUM> is at said high-voltage-level <NUM> may comprise the only distinguishing feature between the first and second forms <NUM>, <NUM> or may be one of a plurality of distinguishing features.

During a directly subsequent second period <NUM>, the reconfiguration signal <NUM> is provided with a lower, positive second voltage <NUM>, which in this example is the same as the second voltage <NUM>. The second period <NUM> may comprise <NUM> microseconds, as an example only. Thus, the second period <NUM> is longer than the second period <NUM>. The duration for which the reconfiguration signal <NUM> is at said second voltage <NUM> may comprise a distinguishing feature of the second form <NUM> of the reconfiguration signal.

During a directly subsequent third period <NUM>, the reconfiguration signal <NUM> is provided at the high-voltage-level <NUM> once again. The third period <NUM> may comprise <NUM> microseconds, as an example only. In this and other examples, the duration of the third period <NUM>, <NUM> may be the same in both signal forms <NUM>, <NUM>.

While the example signal forms of <FIG> are only examples, more generally it can be appreciated that the signal forms comprise a "header" <NUM>, <NUM> and <NUM>, <NUM> that differ in form and convey the information about which bus wire <NUM>, <NUM> to use in the single-ended communication mode. These headers may differ in terms of the duration <NUM>, <NUM> for which the reconfiguration signal is at said high-voltage-level <NUM>, <NUM>. The headers may differ in terms of the duration for which the reconfiguration signal is at a lower voltage level than said high-level-voltage <NUM>, <NUM> between the first period <NUM>, <NUM> at the high-level-voltage and the third period <NUM>, <NUM> at the high-voltage-level <NUM>, <NUM>.

The signal forms <NUM>, <NUM> further comprise a final part <NUM>, <NUM> provided to allow time for the individual nodes <NUM>-<NUM> in the network to reconfigure to the desired communication method. It may thereby be ensured that at the end of the reconfiguration signal (the end of the third period <NUM>, <NUM>), all nodes <NUM>-<NUM> are synchronized and reconfigured to the single-ended communication mode.

In one or more examples, the first part or period <NUM>, <NUM> is configured to communicate the occurrence of the fault to the one or more other nodes. The other nodes, in response to the receipt of the first part <NUM>, <NUM>, may be configured to suspend differential signalling. It will be appreciated that the apparatus may also suspend transmission of differential signalling. The second part <NUM>, <NUM> may comprise a delay before implementation of the single-ended communication. The one or more nodes may be configured to use the delay to perform one or more diagnostic tests and/or to provide time to switch to the single-ended communication mode. The third part <NUM>, <NUM> may communicate the start of the period of single-ended communication. The nodes <NUM>-<NUM> may therefore be configured to begin single-ended communication at a corresponding time, in response to the receipt of the third part <NUM>, <NUM>.

In one or more examples, the high-voltage-level <NUM>, <NUM> and second voltage level <NUM>, <NUM> may be based on supply voltage levels provided to the apparatus <NUM>. Returning to example <FIG>, the apparatus <NUM> typically receives power at two voltage levels. A first power-input terminal <NUM> is configured to receive a first voltage from a first voltage source. The first voltage source may comprise a regulated voltage input at, for example <NUM> V. A second power-input terminal <NUM> is configured to receive a second voltage, greater than the first voltage, from a second voltage source. In an automotive setting, the second voltage source may comprise the vehicle's <NUM> V battery. Thus, the differential signalling provided by the transceiver arrangement <NUM> may be provided with reference to the first voltage and wherein the high-voltage-level is based on or comprises the second voltage, e.g. <NUM> V.

In other examples, the apparatus <NUM> may receive power at a single power input terminal and may include a power converter to provide the different voltage levels required for the reconfiguration signal.

The apparatus <NUM> may be configured to detect receipt of the reconfiguration signal from any of the other nodes <NUM>-<NUM> (or, more particularly, from apparatuses similar to apparatus <NUM> of those other nodes). Thus, the apparatus <NUM> may include reconfiguration signal detection circuitry, which may be part of module <NUM>. The reconfiguration signal detection circuitry may comprise a comparator (not shown) configured to trigger upon receipt of a voltage above a predetermined threshold that would be exceeded by the high-voltage-level <NUM>, <NUM> rather than the normal differential signalling. The reconfiguration signal detection circuitry may include a timer (not shown) for determining the duration of one or more time periods <NUM>, <NUM>, <NUM>, <NUM> based on the occurrence or persistence of the high-voltage-level <NUM>, <NUM>. The determination made by the timer may determine the bus wire used by the nodes <NUM>-<NUM> in the single-ended communication mode.

The apparatus <NUM> may, based on the receipt of the reconfiguration signal from said one or more network nodes <NUM>-<NUM>, provide for switching from use, by said transceiver arrangement <NUM>, of differential signalling to single-ended signalling using only one of said first bus wire <NUM> and second bus wire <NUM>.

We also disclose a method, shown in example <FIG>, performed by a first apparatus <NUM>-<NUM> configured to couple to the first bus wire <NUM> and the second bus wire <NUM> of the communication bus <NUM> and at least one second apparatus <NUM>-<NUM> configured to couple to the first bus wire <NUM> and the second bus wire <NUM> of the communication bus <NUM>. The first apparatus may comprise the transceiver <NUM> of one of the nodes <NUM>-<NUM>. The second apparatus may comprise the transceiver <NUM> of a different one of the nodes <NUM>-<NUM>.

As in the example described above, the first apparatus and the second apparatus each comprising a transceiver <NUM> for communicating with one another via the communication bus <NUM>. Each transceiver <NUM> may be configured to provide differential signalling to the first and second bus wires according to the communication scheme and receive differential signalling from the first and second bus wires according to the communication scheme, wherein the communication scheme defines at least the voltage to be used to provide said differential signalling.

With reference to <FIG>, the method comprises:.

As mentioned previously, the reconfiguration signal is provided for all nodes on the communication bus <NUM>. Thus, in practice, there are typically a plurality of second apparatuses and the method step <NUM> and <NUM> comprise receiving, by the second apparatuses, the reconfiguration signal and collectively switching, by the second apparatuses in response to said receiving of the reconfiguration signal, from transmitting and receiving of the differential signalling to transmitting and receiving single-ended signalling using only one of said first bus wire and the second bus wire.

Further, the transmitting step <NUM> may comprises:.

The apparatus <NUM> and the bus based system <NUM> of which it forms part may have application in a variety of contexts. For example, the system may comprise an Antilock Braking System (ABS), an Electronic Power Steering (EPS) system, or a Heating Ventilation and Air Control (HVAC) system. The apparatus <NUM> may also be applied in body controllers, fuel Pumps, water pumps or oil pumps. Further, the system may comprise an automotive based system or a nonautomotive based system.

Further, although the apparatus <NUM> is disclosed in the context of a CAN based network, the provision of the reconfiguration signal in response to the fault determination signal by the apparatus <NUM> may have application in other network types, such as LIN (Local Interconnect Network), FlexRay, or Ethernet based network buses.

In other examples, the set of instructions/methods illustrated herein and data and instructions associated therewith are stored in respective storage devices, which are implemented as one or more non-transient machine or computerreadable or computer-usable storage media or mediums. Such computerreadable or computer usable storage medium or media is (are) considered to be part of an article (or article of manufacture).

Claim 1:
An apparatus (<NUM>) comprising:
at least a first terminal (<NUM>) configured to couple the apparatus to a first bus wire (<NUM>) of a communication bus (<NUM>) and a second terminal (<NUM>) configured to couple the apparatus to a second bus wire (<NUM>) of the communication bus;
a transceiver arrangement (<NUM>) for communicating with one or more network nodes (<NUM>, <NUM>, <NUM>, <NUM>) via the communication bus, the transceiver arrangement configured to provide differential signalling at the first terminal and the second terminal according to a communication scheme and receive differential signalling from the first terminal and second terminal from the communication bus according to the communication scheme, wherein the communication scheme defines at least a voltage to be used to provide said differential signalling;
the apparatus configured to:
based on a fault detection signal from a fault determination device (<NUM>), the fault detection signal indicative of the occurrence of a fault in at least one of the communication bus and one or more connections between the apparatus and the communication bus, transmit a reconfiguration signal, wherein the reconfiguration signal is provided for transmission via at least one of said first terminal and said second terminal for said one or more network nodes and wherein at least part of the reconfiguration signal has a high-voltage-level comprising a voltage higher than that defined in the communication scheme for said differential signalling; and
wherein said reconfiguration signal is configured to cause the one or more network nodes to provide for switching from use of differential signalling to single-ended signalling using only one of the first bus wire and the second bus wire.