BUS NODE AND PLUGGAGE CONNECTOR FOR A COMMUNICATION BUS SYSTEM WITH BUS TERMINATION MEANS - Patent application

Abstract

The present invention relates to a communication bus system using at least one twisted pair cable as physical medium. Such a communication bus system requires a bus termination at least at an end bus node 100, CU3. Often a communication bus system comprises several identical bus nodes connected to a communication bus B1. The present invention proposes bus nodes CU1-CU3 with an interface circuit IF to the communication bus B1, which interface circuit IF has a bus termination circuit arrangement BT with at least one connection arrangement CC1-CC6 to at least one component J1-J3. In this way it is easy to activate or deactivate the bus termination for a single bus node by manually plugging in a component during the manufacturing process.

Description

[Technical Field]

[0001] The present invention relates to the technical field of networking electronic components in vehicles, particularly commercial vehicles. Vehicles are increasingly equipped with electronic components capable of exchanging messages with each other. Various communication networks have been developed for this purpose. The most frequently used communication protocol in vehicles is the CAN bus communication protocol. CAN bus, which stands for "Controller Area Network," was first seen in vehicles as early as 1991. The CAN bus communication protocol was standardized in 1994 and is numbered ISO 11898. Since then, other variations of the bus system have been standardized. A very prominent example is the so-called vehicle bus, based on the SAE standard J1939 published by the Society of Automotive Engineers (now known as "SAE International"). [Background technology]

[0002] CAN bus wiring typically uses unshielded twisted pair cable as the physical transmission medium, although some manufacturers prefer to use shielded twisted pair cable.

[0003] The CAN bus topology corresponds to a linear bus wire to which multiple bus nodes can be attached. The maximum data rate is 500 kbit / s for the traditional CAN bus and 5 Mbit / s for the CAN-FD (extended payload field) version. ISO 11898 specifies a maximum of 32 CAN nodes connected to the bus wire. ISO standard 11898 specifies that the CAN bus cable is a single twisted-pair cable with a characteristic impedance of 120 Ω. The standard further specifies that both ends of the bus must be terminated with a resistance equal to the characteristic impedance of the cable. Communication over the CAN bus wire requires termination of the bus wire to avoid signal reflections at the cable ends, according to ISO standard ISO 11898-5:2007. The most common bus termination techniques are standard termination and split termination. Standard termination is in the form of a single resistor, while split termination corresponds to two resistors in series with a capacitor connecting the point between them to ground.

[0004] Figure 1 illustrates an example of a standard termination technique. Three bus nodes ECU1-ECU3 are connected to a CAN bus B1. Two twisted-pair bus wires are labeled CH and CL, corresponding to CAN-High and CAN-Low. At both ends of the linear bus wire B1, a twisted-pair cable is terminated by soldering resistor R1 to the bus wires CH and CL. Resistor R1 should have a resistance of 120 Ω, corresponding to the 120 Ω bus cable impedance. Resistor R1 is located internal to bus nodes ECU1 and ECU3. For illustrative purposes, resistor R1 is shown as being integrated into the bus cable. Figure 1 also illustrates the basic architecture of a bus node. References H1-H3 represent the host controllers of each bus node. References CCT1-CCT3 represent the CAN controllers of each bus node ECU1-ECU3. References CT1-CT3 represent the CAN transceivers of each bus node ECU1-ECU3.

[0005] Any Electronic Control Unit (ECU) that wishes to participate in CAN communication needs a CAN interface, which includes a CAN controller and a CAN transceiver. The CAN controller performs the communication functions specified by the CAN protocol and provides significant support to the host. The CAN transceiver connects the CAN controller to the physical transmission medium.

[0006] Figure 2 illustrates the basic split termination technique. The CAN bus is located on the left side of the drawing. Two connection points to the two bus wires, CH and CL, are visible on the left. The CAN transceiver is shown on the right side of the drawing and is labeled CT1. Split termination uses two resistors, R2 and R3, equal to half the characteristic impedance of the cable, i.e., 60 Ω. A capacitor, C1, is also placed between the series connection of the two resistors, R2 and R3, and ground. The capacitance of capacitor C1 is typically 4.7 nF. While the split termination technique uses more components, it offers the added benefit of forming a low-pass filter, preventing high-frequency interference on the bus wire, B1, from passing through the CAN transceiver, CT1.

[0007] More sophisticated bus termination techniques are known, for example from US Pat. No. 5,629,999 and US Pat. No. 5,629,999, which improve the robustness of CAN communication against faults.

[0008] Modern vehicles have a variety of electronic components capable of communicating via internal communication buses, including but not limited to the CAN bus. These include ECUs, sensor units, actuator units, and communication units. Examples of ECUs include engine control units, brake control units, transmission control units, ADAS control units (advanced driver assistance systems), safety system control units such as airbag control units and seatbelt reinforcement control units, and air conditioning control units. Examples of actuator units include electric motors, solenoid valves, electric pumps, electric compressors, and electric heaters. Examples of sensor units include camera units, radar units, lidar units, ultrasonic units, thermal transducers, rotation sensors, voltage measurement units, current measurement units, inertial measurement units, magnetic field measurement units, and optical sensors.

[0009] The components are not connected to a single communication bus, but to multiple communication buses interconnected using gateway units. Sometimes the electronic control unit ECU has a private CAN bus to which all actuators and / or sensors are connected.

[0010] An example of such an ECU is an electronically controlled air suspension system ECU, a so-called ECAS-ECU. Such systems are deployed in commercial vehicles and also in other vehicles such as automobiles.

[0011] FIG. 3 shows a commercial vehicle 10 with three axles: a front axle, a rear axle, and a lift axle. It may be a towing vehicle or other type of utility vehicle. Other examples include utility vehicles used in agriculture, construction vehicles, or campers. Finally, it should be noted that this list is not exhaustive. The term "commercial vehicle" is used here for illustrative purposes only. The present invention can also be used in other vehicles. Thus, passenger cars can be equipped with the subject matter of the present invention as well. Other vehicles include buses, construction machinery, harvesting machines, motorcycles, robots, aircraft, and drones. However, it can also be a trailer vehicle, for example a trailer vehicle used in agriculture or a trailer vehicle attached to a construction vehicle. Large caravans, leisure trailers, and sports trailers are also suitable.

[0012] The vehicle 10 typically has a drive unit equivalent to an internal combustion engine. Of course, other types of drive units can also be incorporated into the towing vehicle. Another example is an electric motor combined with a battery or a fuel cell. Of course, a braking system is also included. In the case of a commercial vehicle, a braking system with service brakes and retarder brakes can be provided. These components are not shown in FIG. 3.

[0013] FIG. 3 illustrates the ECAS system of a commercial vehicle 10. The ECAS-ECU is designated by the reference numeral 100. The remaining components CU1-CU3 are ECAS actuators controlled by the ECAS-ECU 100. These ECAS actuators are so-called ECAS-SPA (Electronically Controlled Air Suspension Smart Pneumatic Actuator) devices. These ECAS actuators CU1-CU3 also have control capabilities and are connected to one or more sensor units that provide feedback on the control process. The main function of the ECAS actuators CU1-CU3 is to increase or decrease the pressure in the air spring bellows FB1-FB6, which are respectively attached to the sides of each axle of the vehicle 10. FIG. 3 illustrates a vehicle with three axles: a front axle VA, a rear axle HA, and a lift axle LA. A pressure accumulator PR is attached to the vehicle 10 to supply compressed air to the vehicle's pneumatic system. The ECAS system is also a pneumatic system and must be connected to the pressure accumulator PR. The pressure lines that conduct compressed air to the ECAS actuators CU1-CU3 are designated by the symbol CAL. Each ECAS actuator CU1-CU3 includes one or more solenoid valves, a host controller, and a bus interface to the ECAS-ECU 100's private CAN bus B1. The ECAS-ECU 100 is connected to a vehicle CAN bus conforming to SAE-J1939 and communicates with other ECUs via the vehicle CAN bus or another vehicle communication bus. The ECAS system uses the ECAS actuators to control the vehicle's suspension characteristics.

[0014] ECAS systems have been used in automobiles since the early 1980s. Sometimes, relatively large steady axle load differences occur on the rear axles of automobiles between empty and full load conditions. These cause problems for the design of steel springs in empty and partial load conditions. The suspension characteristics deteriorate. ECAS systems are used to solve these problems. The main advantages are: a) The full spring deflection can be utilized to compensate for dynamic axle load changes; a) Steady axle load changes are compensated for by pressure changes; C) Improved driving comfort, d) The wheels always stay in close contact with the road, which leads to improved braking and steering behavior and significantly increases tire life. is.

[0015] Suspension control must be performed for each axle or air spring bellow, and the ECAS system has multiple, i.e., two or more, equal ECAS actuators (as modulators, slaves) and one ECAS-ECU (as control device, master).

[0016] 3, there is one ECAS-ECU 100 and three equivalent ECAS actuators CU1-CU3 (one per axle). All four ECAS devices are connected to the same CAN bus B1, but only the first ECAS device 100 and the last ECAS device CU3 must use bus termination in accordance with ISO standard ISO 11898-5:2007.

[0017] Switchable split termination can be realized with the aid of software: from US Pat. No. 5,623,599 a software-controllable CAN bus termination component is known, which allows a bus node to be correctly connected to a CAN bus in a terminated and non-terminated position.

[0018] In the software configuration, a digital output of one microcontroller is used to enable CAN termination. The drawback is that a software failure can interrupt the entire CAN communication for all devices. Furthermore, software-controlled termination is impractical during the CAN identifier learning procedure, which requires CAN termination, because CAN termination can only be performed after each bus node knows its assigned CAN identifier ID (a chicken-and-egg causality dilemma). If a shielded CAN bus cable is required, additional pins are required.

[0019] In the case of switchable termination by hardware means, the split termination resistors R2 and R3 must be integrated into the bus node socket, plug connector or bus cable wiring harness. For split termination, a third pin is required to connect the resistors R2 and R3 to the grounding capacitor C1 to achieve an RC low-pass filter that only affects noise, via a virtual zero. The drawbacks of this design are the increased mechanical complexity in manufacturing, with regard to watertightness, double-occupancy crimp terminals, corrosion protection of solder joints, mechanical stresses and, especially, the costs associated with the third pin. Again, if a shielded CAN bus cable is required, an additional pin is required.

[0020] The midpoint of the split termination is a so-called virtual zero, which means that the voltage at that point is zero due to the need for signal cancellation on the CAN-High and CAN-Low bus wires. The split termination resistors R2, R3 and capacitor C1 form an RC low-pass filter that attenuates only noise signals but does not attenuate the differential CAN bus signal due to the virtual zero.

[0021] There are also several economic constraints for the mass production of such equivalent bus nodes. To produce them cheaply and reduce the level of complexity, equivalent bus nodes should preferably be identical in their manufacturing process. However, the question arises as to how this can be achieved, since CAN termination is only applied to the last device in a series of equivalent devices in a bus node. The last device is defined as the device that is physically farthest from the domain ECU in terms of the wiring harness. For functional safety reasons during the CAN-ID learning procedure, it makes sense to use a hardware solution to configure the bus nodes that should use the bus termination.

[0022] The usual implementation places resistors R2 and R3 between the CAN-High and CAN-Low input pins at the bus node socket. However, in the case of split termination, a third connection to the virtual zero is also required. Therefore, due to the importance of the virtual zero, a simple two-pin solution is not possible. Otherwise, the RC low-pass would affect not only noise but also the differential CAN bus signals. [Prior art documents] [Patent documents]

[0023] [Patent Document 1] U.S. Patent Registration No. 10785066 [Patent Document 2] German Patent Publication No. 102018220073 [Patent Document 3] European Patent Publication No. 2166717 Summary of the Invention [Problem to be solved by the invention]

[0024] Therefore, the object of the present invention is to design a CAN bus termination with a hardware configuration approach that overcomes the above-mentioned drawbacks. In particular, this solution should meet the requirements for mass production of identical bus nodes with the same configuration. Furthermore, for this purpose, only a minimum number of additional pins should be provided in the connector. Manufacturing costs should be minimized. Double-occupancy crimp terminals are not permitted. [Means for solving the problem]

[0025] This object is achieved by a bus node for a communication bus system according to claim 1 and by a plug connector for connecting a communication bus to a socket of the bus node according to claims 14 and 15. The dependent claims contain advantageous developments and improvements of the invention based on the following description of these measures.

[0026] In a general embodiment of the invention, a bus node comprises an interface circuit to a communication bus that requires a bus termination at least at an end of the communication bus, the interface circuit comprising bus termination circuitry, and the bus termination circuitry further comprising at least a connection arrangement for at least one component.

[0027] At its extreme, the invention allows for a bus termination solution in the form of standard or split termination using only two pins without external resistors. If these pins are shorted via a jumper in the wiring harness, the bus termination is enabled, otherwise it is disabled. If these pins are not shorted, the bus termination is disabled, otherwise it is enabled. Furthermore, if a shielded bus cable is used to shield the bus wiring harness, one pin can be internally connected to the so-called bus shield.

[0028] The present invention can be used with different types of communication buses, including but not limited to a CAN bus.

[0029] In one preferred embodiment, the component comprises at least one jumper. The advantage of this proposal is that it is cheap, easy to handle during manufacturing and very reliable, since it allows the jumper to be designed with a gasket so that the contact clamp into which the jumper is inserted is sealed against dirt and moisture, making corrosion not an issue. When a jumper is not inserted into a connection arrangement, the contact clamp is easily protected from dirt and moisture by inserting a blind plug into the corresponding opening.

[0030] With regard to communication buses in the automotive field, it is common for the communication bus to comprise at least one single twisted pair cable as the physical medium, since these are lightweight and relatively inexpensive cables. It is highly advantageous that i) both wires are tightly connected to each other by uniform twisting, minimizing impedance deviations through the wires, and, more importantly, ii) the wires can be more easily installed and twisted so that both wires are the same length to reduce distortion in the cable. It is particularly for these twisted pair cables that the solution according to the present invention is advantageous.

[0031] In one enhanced embodiment, the connection arrangement comprises a single jumper and a contact clamp for bus termination switching means, which enables or disables the termination of at least one twisted pair cable when the single jumper is inserted or removed therefrom. This embodiment allows for a solution that adds only two pins to the connection arrangement. The jumper contacts these two pins when inserted and positioned within the contact clamp. This solution of adding only two pins is appropriate when it is necessary to use a bus connector with minimal size and low cost. Another advantage relates to the long-term reliability of the connector. When a connector has a minimal number of pins, the risk of corrosion and poor contact is reduced. For connectors of the same size, these pins have a greater thickness, which improves contact quality and mechanical stability.

[0032] It is advantageous to provide at least one electronic switch in the bus termination switching means, which is controlled by the voltage drop occurring when a single jumper is inserted into or removed from its corresponding contact clamp. Such an electronic switch can be provided either separately in the electronic circuit or integrated in an integrated circuit. Different types of electronic switches are available, which allows for great flexibility in the design of the electronic circuit of the bus termination switching means.

[0033] In particular, transistors are used as electronic switches. Many different types of transistors can be used as required. Regarding the "active low" configuration of the bus termination switching means using N-channel enhancement-mode MOSFET transistors, it is advantageous for the bus termination switching means to further comprise an inverter whose input is connected to a pull-up resistor, at which a high potential is present. The inverter inverts the potential at its input, causing a low potential at its gate electrode, so that the N-MOSFET transistor is held in a non-conductive state. When the pin connected to the gate of the N-MOSFET transistor goes to a low potential, i.e., when a high potential is present at the gate due to the inverter, the MOSFET transistor is switched into a conductive state, thereby enabling the bus termination. The inverter converts the low potential at its output into a high potential, so that the transistor is in a conductive state. The pull-up resistor has the effect that the bus termination remains disabled unless a jumper is inserted into the contact clamp (normally-off configuration).

[0034] For the active low configuration, the first contact clamp is advantageously connected to the input of the inverter, and the second contact clamp is advantageously connected to ground either directly or via a resistor, with a pull-up resistor also being connected to the conductor path connecting the first contact clamp to the input of the inverter.

[0035] This solution has the additional advantage that the second contact clamp is electrically connected to the shield of the twisted pair cable. If a shielded bus cable is used, only a single pin needs to be added to the connector configuration. A high resistance resistor (preferably 11 kΩ) is placed between the first contact clamp and ground. Preferably, this type of resistor should be sized to withstand the long-term erroneous current flow resulting from a reverse polarity fault.

[0036] Another embodiment of the present invention relates to an "active high" configuration of the bus termination switching means, in which the at least one electronic switch is also a transistor, in particular an N-channel enhancement-mode MOSFET transistor, the gate electrode of which is connected to a pull-down resistor and a first contact clamp for a single jumper, and the second contact clamp for a single jumper is connected to a voltage source. The advantage of this configuration is that no inverters need to be introduced into the circuit design.

[0037] A variant of the invention that does not require an electronic switch is also proposed, which comprises contact clamps for two jumpers in the connection configuration described above, the first jumper connecting a first bus wire of the twisted pair cable to a first end of the termination circuit when inserted into or removed from its corresponding contact clamp, and the second jumper connecting a second bus wire of the twisted pair cable to a second end of the termination circuit when inserted into or removed from its corresponding contact clamp.

[0038] All of these different variations and embodiments are suitable for the two most common bus termination techniques: standard termination and split termination.

[0039] To achieve the termination, the termination circuit advantageously comprises either a single termination resistor for standard termination, or a split termination configuration consisting of two termination resistors connected in series and a coupling capacitor connected to ground and the series connection of the two termination resistors.

[0040] The proposed invention can advantageously be used in a bus node further comprising an electronic unit configured to perform control of the vehicle's actuators and / or an electronic unit configured to perform data collection of the vehicle's sensor units.

[0041] One example of an advantageous use of the invention is an electronic unit adapted to perform the control of at least one solenoid valve of an electronically controlled air suspension system ECAS of a vehicle.

[0042] Likewise, the electronic unit is configured to carry out data acquisition of sensors, in particular distance sensors or pressure sensors, of the vehicle's electronically controlled air suspension system ECAS.

[0043] Another embodiment of the invention relates to a plug-in connector for connecting a communication bus to a socket of a bus node according to the invention. The plug-in connector comprises contact clamps for two jumpers and contact clamps for the twisted pair wires of the communication bus, such that when a first jumper is plugged in, the first jumper connects a first twisted pair wire of the communication bus with a first end of a termination circuit in the bus node, and when a second jumper is plugged in, the second jumper connects a second twisted pair wire of the communication bus with a second end of a termination circuit in the bus node. Such a plug-in connector is suitable for networks configured to provide a connection configuration for two jumpers.

[0044] Similarly, another embodiment of the invention is a plug-in connector for connecting a communication bus to a socket of a bus node according to the invention, the plug-in connector comprising contact clamps for a single jumper and contact clamps for the twisted pair wires of the communication bus, characterized in that when the plug-in connector is plugged into said socket of said bus node, the first contact clamp for the single jumper is connected to a control line of the bus termination circuitry and the second contact clamp is connected to a supply voltage line or a ground line. This embodiment is adapted to use the single jumper solution according to the invention.

[0045] An extended solution for a single jumper plug connector comprises the second contact clamp being further connected to the shield of the twisted pair cable, this solution is suitable for terminating shielded twisted pair cables and requires only one additional pin on the cable connector.

[0046] In the following, an embodiment of the invention is illustrated in the drawings and will be described in detail with reference to the drawings. [Brief explanation of the drawings]

[0047] [Figure 1] Block diagram of a method for interconnecting electronic components using a CAN bus [Figure 2] Circuit diagram for implementing split termination in a CAN node [Figure 3] Schematic of a commercial vehicle with three axles [Figure 4] Schematic diagram of the use of this split termination implementation for the end node of a CAN bus in a commercial vehicle as shown in FIG. [Figure 5] Schematic diagram of a switchable CAN bus termination solution based on a simple component in the form of a single jumper to achieve active low [Figure 6] Schematic diagram of a switchable CAN bus termination solution based on a simple component in the form of a single jumper to achieve active high [Figure 7]Schematic diagram of a second proposed switchable CAN bus termination solution based on two components in the form of jumpers [Figure 8] Schematic diagram of the interconnection of three identical bus nodes using a CAN bus cable, with two jumpers inserted only at the end bus node, so that bus termination is only active at the end bus node DETAILED DESCRIPTION OF THE INVENTION

[0048] This description will clarify the basis of the present disclosure, and it will be appreciated that those skilled in the art will be able to devise various configurations that, although not explicitly described herein, embody the basis of the present disclosure and are intended to be protected within their scope.

[0049] 4 illustrates the connection between the ECAS-ECU 100 and the three ECAS units CU1 to CU3, as well as the CAN bus B1. The ECAS-ECU 100 and the terminal ECAS unit CU3 are provided with a bus termination circuit in the form of split termination, with termination resistors R2 and R3 and a coupling capacitor C1 between them.

[0050] Efficient mass production of identical ECAS units CU1-CU3 requires identical circuit designs. To address this, the present invention provides each ECAS unit CU1-CU3 with a termination circuit, either in the form of standard termination or split termination. This termination circuit is part of a broader bus termination circuit configuration that is expanded by supporting circuitry to place simple components that can enable or disable bus termination in each ECAS unit CU1-CU3. Such simple components represent hardware solutions. Examples of these are simple jumpers and switches, such as DIP switches. However, DIP switches are not as reliable as jumpers, especially in terms of protection against moisture, dirt, and mechanical vibrations. Jumpers are inserted into their corresponding contact clamps and remain there for the product's lifetime. Another, more sophisticated example of a component is photoelectric material. Such devices are known in the form of electrically programmable EPROM memories. After individual ECAS units are installed during mass production of vehicles, for ECAS units requiring bus termination, technicians manually erase the EPROM memory using an ultraviolet lamp. The bus termination circuitry can be designed so that the termination is normally off and is only switched on after erasing the EPROM memory, or vice versa.

[0051] FIG. 5 illustrates a first detailed embodiment of the present invention, which relates to a solution using a single jumper as a component. IF denotes a CAN bus interface circuit. A CAN bus interface typically consists of a CAN transceiver and a CAN controller. Only the CAN transceiver CT1 is shown here. However, this CAN transceiver CT1 is shown connected to an internal bus IB, which connects the CAN transceiver CT1 to a CAN controller chip (not shown), which may be a standalone chip or integrated into the ECAS device's host controller. The twisted wire pair of the CAN bus B1 is shown on the left. The bus shield is labeled BS. This is a conventional one- or two-layer metallic shield, commonly known as a braided wire or metal foil. The bus cable terminates in a plug connector PL, which is equipped with a number of contact pins. The CAN-High bus wire CH is crimped to the first pin of the plug connector PL at contact point CC1. The CAN-Low bus wire CL is crimped onto the second pin of the plug connector PL at contact point CC2. Furthermore, this plug connector PL is equipped with two additional pins: one associated with contact clamp CC3 and the other with contact clamp CC4. For assembly purposes, a jumper J1 is inserted into the contact clamps CC3 and CC4. A socket S1 into which the plug connector PL is inserted is attached to the ECAS device CU1-CU3. The socket S1 has corresponding contact clamps CC1-CC4 into which the contact pins of the plug connector PL are inserted. The interface circuit IF further comprises a bus termination circuit arrangement BT. This arrangement comprises a termination circuit ST, a bus termination switching means BTS, and further individual components. The most important components are the contact clamps CC1-CC3 in the socket S1. CC1 and CC2 are connected to the internal bus wires leading to the CAN bus transceiver CT1. These bus wires are also connected to the termination circuit ST already presented above, which comprises the two resistors R2, R3 and the coupling capacitor C1 of the split termination, to which a bus termination switching means BTS has been added.These include two transistors T1 and T2 and an inverter IL. These transistors T1 and T2 are illustrated as N-channel enhancement-mode MOSFET transistors. The output of the inverter IL is connected to the gate electrodes of transistors T1 and T2. The drain electrode of transistor T1 is connected to resistor R2. The drain electrode of transistor T2 is connected to resistor R3. The source electrodes of transistors T1 and T2 are both connected to capacitor C1. The input of the inverter IL is forward connected to diode D1, which is connected to contact clamp CC3. A high-resistance pull-up resistor R4 is connected to the power supply voltage and precedes diode D1. Resistor R5 is connected to contact clamp CC4 and to ground.

[0052] This bus termination circuit configuration BT is a so-called "BT normally-off" circuit design, and its function is as follows. When the plug-in connector PL is inserted into the socket S1, unless the jumper J1 is inserted, the following occurs: the bus wires CH and CL are connected to the CAN transceiver CT1 and the termination circuit ST. Because the resistance of the pull-up resistor R4 is 11 kΩ, which is low compared to the high resistance of the inverter IL, the potential at the input of the inverter IL remains high, and split termination is not enabled. Because the potential at the input of the inverter IL is high, the potential at its output is low, so that the transistor is held non-conductive via its gate electrode. Now, if the jumper J1 is inserted between the contact clamps CC3 and CC4 of the plug-in connector PL, the resistance of the resistor R5 to ground is low, e.g., 1 kΩ, resulting in a large voltage drop across the pull-up resistor R4. Thus, the potential at the input of the inverter IL is low, causing a high potential at its output, which in turn switches the transistors T1 and T2 into a conductive state, thereby enabling and operating the termination circuit ST. The diode D1 only serves as a protection diode against accidental reverse polarity contact. Therefore, this diode D1 is not necessary for the bus termination circuit configuration BT to function. The manufacturer can decide which ECAS units CU1 to CU3 they want to enable bus termination for. As explained previously, bus termination must be enabled at least at the end of the CAN bus B1. In the example of Figures 3 and 4, bus termination is enabled only in the ECAS unit CU3. Therefore, jumper J1 is inserted only in the ECAS unit CU3. It should be noted that for the ECAS-ECU 100, bus termination is always enabled, so a jumper configuration method is not necessary. This can be easily achieved by hardwiring.

[0053] In one embodiment, the voltage source 30 corresponds to a "clamp 30" corresponding to a battery voltage in the automotive field. In another embodiment, the voltage source corresponds to a "clamp 15" corresponding to a switched battery voltage in the automotive field, for example, after pressing the start button.

[0054] Due to the high-resistance resistor R5 (preferably 11 kΩ) between the contact clamp CC4 and ground, the pin of the contact clamp CC4 can also be used to contact the CAN bus shield BS. Although the CAN bus shield BS is not always necessary, some customers prefer to have it because it improves noise immunity. This is another advantage of this circuit design. This type of resistor must be sized so that it can withstand long-term erroneous currents due to the inadvertent occurrence of a reverse polarity fault. Furthermore, the pull-up resistor does not necessarily have to be implemented in the form of a single physical component. It can also be realized by a separate circuit consisting of several passive and active electronic components. For example, this is advantageous for achieving lower steady-state currents.

[0055] FIG. 6 illustrates a proposed circuit design for a so-called "active-high" configuration. The same reference numerals represent the same components as in FIG. 5. The difference is that the inverter IL is not required. However, excluding the inverter IL requires regulating the power supply voltage. Resistor R6 replaces pull-up resistor R4 but is connected to ground potential, thus acting as a pull-down resistor. Ground potential is often referred to as "clamp 31" in the automotive field. Resistor R7 replaces pull-down resistor R5 and is connected to power supply voltage 30. Resistor R7 has a resistance of 11 kΩ, and resistor R6 has a resistance of, for example, 100 kΩ. When jumper J1 is not inserted, the potential of the gate electrodes of transistors T1 and T2 remains "low," thereby keeping transistors T1 and T2 in a non-conductive state due to the pull-down resistor. When jumper J1 is inserted, pull-up resistor R7 supplies a high potential to the gate electrodes, switching transistors T1 and T2 into a conducting state and thereby enabling the split termination. Thus, the "active high" configuration according to Figure 6 provides the same "BT normally off" functionality as the "active low" configuration of Figure 5.

[0056] Similarly, the circuit design can be configured to provide a "BT normally-on" function. This can be easily achieved by replacing enhancement-mode MOSFET transistors with depletion-mode MOSFET transistors. Alternatively, different circuit designs can be implemented using bipolar transistors or other forms of electronic switches, including so-called "bilateral switches."

[0057] FIG. 7 illustrates another embodiment using two jumpers as components. Again, the same reference numerals represent the same components as in FIG. 5. This two-jumper solution has the advantage that no bus termination switching means are required in the interface circuit IF. This termination circuit ST remains in the interface circuit IF, but is manually contacted, thereby eliminating the need for electronic control. The bus termination switching means in the form of two transistors and an inverter can be omitted, thus making the electronic circuit design less expensive. As long as no jumpers are inserted in the plug socket PL, the ECAS device remains without bus termination. The first jumper J2 is inserted into contact clamps CC5 and CC7. In this way, the bus wire CH is connected to the branch of resistor R2 of the split termination circuit ST. The second jumper J2 is inserted into contact clamps CC6 and CC8. In this way, the bus wire CL is connected to the branch of resistor R3 of the split termination circuit ST. This solution has the advantage that the cost of the bus termination circuitry BT is significantly reduced, while on the other hand the costs for the plug-in connector PL2 and the socket S2 increase, thus providing greater flexibility in choosing the circuit design according to need.

[0058] In another embodiment of the present invention, the hardware configuration solution described above can be combined with the software-controlled termination enablement method by implementing a wired-OR characteristic (either jumper-based enablement or software-controlled enablement) or a wired-AND characteristic, where software-controlled enablement is performed only if the enablement is confirmed by the hardware-based configuration, or vice versa (two-factor confirmation), and bus termination enablement / disablement is only valid.

[0059] FIG. 8 illustrates a typical practical implementation of connecting equivalent bus nodes to a CAN bus. As previously explained, this CAN bus topology corresponds to a linear bus topology. This can be achieved by using a single linear bus cable B1 to which the end bus nodes 100 and CU3 are connected, as shown in FIG. 4, and separate cable branches for the intervening bus nodes CU1 and CU2. These cable branches are physically connected to the linear bus cable B1. Instead of using this type of wire harness, which is not easy to manufacture, it is more practical to use the CAN bus cable connection shown in FIG. 8. In practice, two cables are attached to the plug connectors for the ECAS units CU1 and CU2. For the ECAS unit CU1, a first cable comes from the ECAS-ECU 100, and a second cable extends the bus wires to the ECAS unit CU2. For the plug connector for the ECAS unit CU2, a first cable comes from the ECAS unit CU1, and a second cable extends the bus wires to the ECAS unit CU3. With respect to the ECAS device CU3, only one cable is attached to the plug connector coming from the ECAS device CU3. Therefore, because the ECAS device CU3 is the end device, two pins of the plug connector PL, which are provided for further extending the bus wires, remain free. Because these two pins are unused, they can be used for a bus termination configuration by inserting two jumpers, as illustrated in FIG. 7 and also in FIG. 8. The different pins of the plug connector PL of the ECAS device CU3 are labeled with the same reference numerals as those used in FIG. 7. Note that while FIG. 8 illustrates pins CC1 and CC2 as being on the left side, these pins are actually located on the left side where pins CC5-CC7 are also located. In this regard, this drawing has been simplified for illustrative purposes.

[0060] 5-7 show jumpers J1-J3 in the form of rigid wires. However, it should be noted that jumpers made from flexible wires can also be used. Here, a single jumper exits a connector and returns to the same connector. In another embodiment, a two-connector solution is used to connect bus nodes. In that case, a jumper exits a first connector and returns to a second connector.

[0061] All examples and conditional language described herein are intended to be understood as not being limited to such specifically recited examples. For example, those skilled in the art will appreciate that the block diagrams presented herein represent conceptual diagrams of example circuits. Similarly, it will be appreciated that the illustrated flowcharts, state diagrams, pseudocode, and the like are various variations for representing processes substantially stored on a computer-readable medium and therefore executable by a computer or processor.

[0062] The present disclosure is not limited to the embodiments described herein. Various adaptations and modifications of the present disclosure are possible and will occur to those skilled in the art based on their technical capabilities. In particular, the application of the present invention is not limited to equivalent ECAS devices. Other equivalent devices exist in multiple forms on vehicles. Vehicles typically have multiple brake actuators for different wheels, e.g., to realize electric parking brakes that are also electronically controlled via a CAN bus. Furthermore, the present invention is not limited to applications via a CAN bus. Multiple communication bus systems that utilize a physical medium in the form of twisted pair cables are readily available on the market, where bus termination is also an issue. The present invention can also be used with these communication bus systems. Furthermore, the present invention can also be used with communication bus systems outside the automotive field, such as field bus systems for machine control, process control, and plant control. The present invention may also include the following aspects: 1. A bus node having an interface circuit (IF) for a communication bus (B1), which requires a bus termination at least at the end of the communication bus (B1); This interface circuit (IF) has a bus termination circuit configuration (BT), At the bus node, A bus node characterized in that the bus termination circuit configuration (BT) comprises at least one connection configuration (CC1 to CC6) for at least one component (J1 to J3). 2. In the bus node described in 1 above, A bus node in which the components (J1 to J3) include at least one jumper (J1 to J3). 3. In the bus node described in 1. or 2. above, A bus node in which said communication bus (B1) comprises at least one single twisted pair cable as a physical medium. 4. In the bus node described in 3 above, A bus node, wherein the connection configuration (CC1 to CC6) comprises a single jumper (J1) and contact clamps (CC3, CC4) for a bus termination switching means (BTS), the bus termination switching means (BTS) enabling or disabling the termination of the at least one twisted pair cable when the single jumper (J1) is inserted or removed therefrom. 5. In the bus node described in 4. above, The bus node includes a bus termination switching means (BTS) having at least one electronic switch (T1, T2) controlled by the voltage drop that occurs when the single jumper (J1) is inserted into or removed from its corresponding contact clamp (CC3, CC4). 6. In the bus node described in 5 above, For an active low configuration of said bus termination switching means (BTS), said at least one electronic switch (T1, T2) is a transistor, in particular an N-channel enhancement mode MOSFET transistor, and said bus termination switching means (BTS) further comprises an inverter (IL) controlling at least one transistor, the input of which is connected to a pull-up resistor (R4) connected to the bus node. 7. In the bus node described in 6. above, A bus node in which the first contact clamp (CC3) is connected to the input of the inverter (IL) and the second contact clamp (CC4) is connected to ground either directly or via a resistor (R5). 8. In the bus node described in 7. above, The bus node, wherein said second contact clamp (CC4) is also electrically connected to the shield (BS) of said twisted pair cable. 9. In the bus node described in 5. above, For an active high configuration of the bus termination switching means (BTS), the at least one electronic switch (T1, T2) is a transistor, in particular an N-channel enhancement mode MOSFET transistor, the control electrode of the transistor being connected to a pull-down resistor (R6) and to a first contact clamp (CC3) for a single jumper (J1), the second contact clamp (CC4) for the single jumper (J1) being connected to a voltage source (30) at the bus node. 10. In the bus node described in 3. above, A bus node, wherein the connection configuration comprises contact clamps (CC5, CC6, CC7, CC8) for two jumpers (J2, J3), wherein a first jumper (J2) connects a first bus wire (CH) of the twisted pair cable to a first end of a termination circuit (ST) when the first jumper (J2) is plugged into or unplugged from its corresponding contact clamp (CC5, CC7), and a second jumper (J3) connects a second bus wire (CL) of the twisted pair cable to a second end of the termination circuit (ST) when the second jumper (J3) is plugged into or unplugged from its corresponding contact clamp (CC7, CC8). 11. In the bus node according to any one of items 4 to 10 above, A bus node in which the termination circuit (ST) comprises a single termination resistor (R1) or a split termination circuit configuration consisting of two termination resistors (R2, R3) connected in series and one coupling capacitor (C1), the coupling capacitor (C1) being connected to ground and to the series connection of the two termination resistors (R2, R3). 12. In the bus node according to any one of 1. to 11. above, The bus node comprises an electronic unit configured to perform control of actuators of the vehicle (10) and / or an electronic unit configured to perform data collection of sensor units of the vehicle (10). 13. In the bus node described in 12. above, The bus node, wherein the electronic unit is configured to perform the control of at least one solenoid valve of an electronically controlled air suspension system ECAS of the vehicle (10). 14. A plug connector (PL) for connecting a communication bus (B1) to a socket (S1) of a bus node (ECU, CU1 to CU3) according to any one of 1. to 3. above, This plug-in connector (P1) is provided with contact clamps (CC5, CC6, CC7, CC8) for two jumpers (J2, J3) and contact clamps (CC1, CC2) for the twisted pair wire of the communication bus (B1), and the first jumper (J2), when plugged in, connects the first twisted pair wire (CH) of the communication bus (B1) to one end of the termination circuit (ST) of the bus node, and the second jumper (J3), when plugged in, connects the second twisted pair wire (CL) of the communication bus (B1) to the other end of the termination circuit (ST) in the bus node (ECU, CU1 to CU3). 15. A plug connector (PL) for connecting a communication bus (B1) to a socket (S1) of a bus node (ECU, CU1 to CU3) according to any one of 4 to 9 above, This plug-in connector (P1) is provided with contact clamps (CC3, CC4) for a single jumper (J1) and contact clamps (CC1, CC2) for the twisted pair wires of the communication bus (B1), and when this plug-in connector (PL) is plugged into the socket (S1) of the bus node (ECU, CU1 to CU3), the first contact clamp (CC3) is connected to the control line of the bus termination circuit configuration (BT) and the second contact clamp (CC4) is connected to the power supply voltage line or the ground line. 16. In the plug connector (PL) described in 15 above, The second contact clamp (CC4) is further connected to the shield (BS) of the twisted pair wire cable. [Explanation of symbols]

[0063] 10 vehicles 100 ECAS-ECU B1 communication bus BS Bus Shield BT bus termination circuit configuration BTS bus termination switching means ECU1 to ECU3 Electronic Control Unit D1 Diode CAL pressure line CC1~CC8 Connector Clamp CH CAN-High bus wire CL CAN-Low bus wire CT1~CT3 CAN transceivers CTR1~CTR3 CAN controllers CU1~CU3 Solenoid valve control units C1 capacitor FB1~FB6 Air Spring Bellow HA rear axle H1~H3 Host IB Internal communication bus IF interface circuit IL inverter J1~J3 jumpers LA Lift Axle PR pressure accumulator PL1, PL2 plug connector R1 terminating resistor R2,R3 split terminating resistor R4 pull-up resistor R5 pull-down resistor R6 pull-down resistor R7 pull-up resistor S1 Insertion Socket ST split end T1, T2 transistors VA front axle

Claims

1. A bus node comprising an interface circuit (IF) for a communication bus (B1), which requires a bus termination at least at an end point of the communication bus (B1); The interface circuit (IF) has a bus termination circuit configuration (BT), At the bus node, The bus termination circuit arrangement (BT) comprises at least one connection arrangement (CC1-CC8) for at least one component (J1-J3), said communication bus (B1) comprises at least one single twisted pair cable as a physical medium, said connection arrangement comprising contact clamps (CC5, CC6, CC7, CC8) for two jumpers (J2, J3), a first jumper (J2) being adapted to connect a first bus wire (CH) of the twisted pair cable to a contact clamp (CC5, CC7) of the termination circuit (ST) when the first jumper (J2) is inserted into or removed from its corresponding contact clamp (CC5, CC7). a bus node connected to the first end, and having a second jumper (J3) connected to a second end of the twisted pair cable when the second jumper (J3) is inserted into or removed from the corresponding contact clamp (CC7, CC8), connecting a second bus wire (CL) of the twisted pair cable to a second end of the termination circuit (ST), the termination circuit (ST) comprising a single termination resistor (R1) or a split termination circuit configuration consisting of two termination resistors (R2, R3) connected in series and a coupling capacitor (C1), the coupling capacitor (C1) being connected to ground and the series connection of the two termination resistors (R2, R3).

2. 2. The bus node according to claim 1, A bus node wherein said components (J1-J3) comprise at least one jumper (J1-J3).

3. 2. The bus node according to claim 1, A bus node, wherein the connection arrangement (CC1 to CC6) comprises a single jumper (J1) and contact clamps (CC3, CC4) for a bus termination switching means (BTS), the bus termination switching means (BTS) enabling or disabling the termination of the at least one twisted pair cable when the single jumper (J1) is inserted or removed therefrom.

4. 4. The bus node according to claim 3, The bus node, wherein the bus termination switching means (BTS) comprises at least one electronic switch (T1, T2) controlled by the voltage drop occurring when the single jumper (J1) is inserted into or removed from its corresponding contact clamp (CC3, CC4).

5. 5. The bus node according to claim 4, For an active low configuration of the bus termination switching means (BTS), the at least one electronic switch (T1, T2) is a transistor, in particular an N-channel enhancement mode MOSFET transistor, and the bus termination switching means (BTS) further comprises an inverter (IL) controlling the at least one transistor, the input of which is connected to a pull-up resistor (R4) at the bus node.

6. 6. The bus node according to claim 5, A bus node in which the first contact clamp (CC3) is connected to the input of the inverter (IL) and the second contact clamp (CC4) is connected to ground either directly or via a resistor (R5).

7. 7. The bus node according to claim 6, A bus node in which said second contact clamp (CC4) is also electrically connected to the shield (BS) of said twisted pair cable.

8. 5. The bus node according to claim 4, For an active high configuration of said bus termination switching means (BTS), said at least one electronic switch (T1, T2) is a transistor, in particular an N-channel enhancement mode MOSFET transistor, the control electrode of the transistor being connected to a pull-down resistor (R6) and to a first contact clamp (CC3) for a single jumper (J1), and a second contact clamp (CC4) for the single jumper (J1) being connected to a voltage source (30) at the bus node.

9. A bus node according to any one of claims 1 to 8, The bus node comprises an electronic unit configured to perform control of actuators of the vehicle (10) and / or an electronic unit configured to perform data collection of sensor units of the vehicle (10).

10. 10. The bus node according to claim 9, A bus node, wherein said electronic unit is configured to perform the control of at least one solenoid valve of an electronically controlled air suspension system ECAS of a vehicle (10).

11. A plug-in connector (PL) for connecting a communication bus (B1) to a socket (S1) of a bus node (ECU, CU1 to CU3) according to claim 1 or 2, The plug-in connector (P1) comprises contact clamps (CC5, CC6, CC7, CC8) for two jumpers (J2, J3) and contact clamps (CC1, CC2) for the twisted pair wires of the communication bus (B1), wherein the first jumper (J2), when plugged in, connects the first twisted pair wires (CH) of the communication bus (B1) to one end of the termination circuit (ST) of the bus node, and the second jumper (J3), when plugged in, connects the second twisted pair wires (CL) of the communication bus (B1) to the other end of the termination circuit (ST) in the bus node (ECU, CU1 to CU3).

12. A plug-in connector (PL) for connecting a communication bus (B1) to a socket (S1) of a bus node (ECU, CU1 to CU3) according to any one of claims 3 to 8, This plug-in connector (P1) comprises contact clamps (CC3, CC4) for a single jumper (J1) and contact clamps (CC1, CC2) for the twisted pair wires of the communication bus (B1), characterized in that when this plug-in connector (PL) is plugged into the socket (S1) of the bus node (ECU, CU1 to CU3), the first contact clamp (CC3) is connected to the control line of the bus termination circuit configuration (BT) and the second contact clamp (CC4) is connected to the power supply voltage line or the ground line.

13. 13. A plug-in connector (PL) according to claim 12, The plug-in connector wherein the second contact clamp (CC4) is further connected to the shield (BS) of the twisted pair wire cable.

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