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Repeaters, Bridges and Gateways

CAN Repeaters

Repeaters are used to establish the physical coupling of two or more segments of a CAN bus system. They can be used to implement tree or star topologies as well as long spur lines. In addition, network segments can be electrically decoupled using a galvanically isolated repeater.

The lines coupled by the repeater are independent electric segments that can be optimally terminated in terms of signals. In this way topologies can be implemented that are not possible with a pure line of the bus due to electrical reflections.

The division of a CAN system into several subsystems connected via CAN repeaters also allows the maximum number of bus subscribers defined by the transceiver output capacities to be increased.

As messages are not addressed in CAN, the repeater logic has to translate the signals of the segment received into the other signals in each case and ensure that the input signals are not back-coupled. In terms of signals, the repeater corresponds to a line with relevant delay time. It cannot therefore be used to extend a CAN system.

Using repeaters does not influence the real-time behavior of a system, because in terms of transmission behavior it corresponds to a network that only consists of lines.

Another area of application of repeaters is the coupling of different physical CAN layers, e.g. by means of high/low-speed repeaters or optical repeaters.

The repeaters offered by IXXAT have an additional monitoring function. Connected network segments that are disturbed by permanent dominant levels, are detected and automatically disconnected, thus enabling the remaining network to continue functioning normally. After the fault has been eliminated, the operation of a disconnected segment is detected and the segment can automatically be reconnected to the network.

IXXAT also offers the repeater technology for licensed integration in customer hardware.

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Conventional bus structure
Signaling distance between two furthest nodes (1/9) is 220 metres

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Extended structure with spur line
Signaling distance between two furthest nodes (1/6 or 6/9) is 140 metres

CAN Bridges and Gateways

CAN bridges and CAN gateways are infrastructure components with which complex network structures can be implemented.

CAN bridges can connect CAN networks of different bit rates or protocols with each other. They are based on the store-(modify)-forward principle, where CAN messages are received by a sub-network and then transmitted in the other sub-network.

Translation and filter rules can also be used, by means of which, for example, a protocol adaptation can be carried out between the sub-networks. A bridge can therefore also provide simple gateway functions.

Compared to the CAN repeater, the CANbridge enables the enlargement of the maximum network size, so that the sub-systems work fully self-sufficiently with regard to bus arbitration. CAN sub-networks connected by bridges are independent of each other in terms of their real-time behavior and are to be regarded as independent networks.

CAN-bridges are suited to creating hierarchical networks by transferring only the information to the connected sub-network via bridges which are relevant for the sub-network. The bridge function can be executed with the aid of other transmission systems. For example, the CAN-Ethernet-CAN bridge is connected via two Ethernet-TCP/IP gateways which enable connection to remote CAN networks.

As an extension to the CAN bridges, CAN gateways enable access to CAN networks via other communication systems. The protocols of the connected bus systems are mapped in the other communication model in each case.

In this way, for example, devices with only one serial port can be connected to CAN/CANopen networks via CAN/CANopen-RS232 gateways. Gateways can also provide remote accesses to CAN networks. The CAN-TCP/IP gateway, for example, thus enables worldwide access to the CAN network, e.g. for diagnosis and service purposes.

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Connection of CAN networks with the CANbridge

Overview of IXXAT CAN topology products

Click on the name of the product for more information:

CAN Repeaters CAN Bridges CAN Gateways

CAN@net II/Generic


CAN@net II/Generic



CANblue II