DE19515194C2 - Communication network - Google Patents

Description

The invention relates to a communication network for control of a vehicle. DE 41 10 372 A1 relates to a multiplex Transmission system for vehicles, which consists of several Data transmission networks composed over a Network nodes are connected to each other. About this Network nodes can receive information from a Network into the other.

DE 41 26 449 A1 describes a control or Control system for vehicles, in which two networks used across a number of interfaces communicate with each other. transmission lines low speed and High speed transmission lines can be used become.

DE 44 01 785 A1 describes an integrated one Wiring system for an integrated Communication device for a vehicle control system. On first protocol is used to generate signals at a first Transfer speed, and a second protocol is used to send signals at a second speed to transfer. There are a variety of Communication interface units for communicating with Terminal control units according to a variety of Communication protocols provided. each Communication interface unit uses one  different communication protocol for communicating with certain vehicle systems at a speed that are different from other communication interface units different. A predetermined pattern is used to the communication interface units alternately operate.

DE 42 27 577 C1 relates to a method for bidirectional signal transmission. Here is one bidirectional signal transmission after the master-slave Principle between one control unit (master) and several electronic modules (slave). The The master signal is voltage-coded and the slave signals are current coded and the master signal becomes continuous sent with a fixed timing and the slave signals are sent correlated to the time clock of the master.

Fig. 9 is a block diagram to show a communication network for a conventional electronic control device. In the figure, reference numerals 31 , 32 , 33 and 34 denote electronic control devices (hereinafter referred to as ECUs), and reference numerals 311 , 321 , 331 and 341 denote CPUs, each of which is installed in each of the ECUs 31 , 32 , 33 and 34 is. The ECU 31 functions as a main computer for engaging the mutual communication initiative of the ECUs. Reference numerals 312 , 322 , 332 and 342 denote transmission-only interfaces, each of which is installed in each of the ECUs 31 , 32 , 33 , 34 , and reference numerals 313 , 323 , 333 and 343 denote reception-only interfaces, of which each is installed in each of the ECUs 31 , 32 , 33 , 34 . Each of the CPUs 311 , 321 , 331 , 341 is provided with an output port Tx and an input port Rx.

Numeral 40 denotes a communication line made of a wire or an optical fiber for connecting the ECUs 31 , 32 , 33 , 34 . The communication line 40 serves as a bus bar, which is shared for the ECUs 31 , 32 , 33 , 34 . The communication network has a bus structure.

Operation of the communication network described above is as follows.

When the ECU 31 as the main computer requests data for the ECU 32 , a data request signal is transmitted from the transmission-only interface 312 via the communication line to the reception-only interface 323 of the ECU 32 . When the ECU 32 receives the data request signal, the read-out data is transmitted from the transmission-only interface 322 via the communication line 40 to the reception-only interface 313 of the ECU 31 . In this case, the ECUs 33 and 34 also receive the data request signal from the ECU 31 . However, the data request signal contains such information that communication is made only for the ECU 32 . Accordingly, only the ECU 32 operates to send the signal back, and the ECUs 33 and 34 do not operate to send the signal back.

Since the communication network with the ECUs has the construction described above, the ECU 33 and ECU 34 , which are not necessarily involved in the communication, receive communication data via the communication line 40 , even in the case where the ECU 31 is involved the ECU 32 communicated, and therefore there was a malfunction of erroneous operation of the ECU 33 and the ECU 34 . Furthermore, the communication line between the ECU 33 and the ECU 34 , which was not involved in the communication, was seized for use, and it was impossible to use the communication line.

There is also a requirement to standardize the Methods of communicating among the ECUs. However with the different techniques of conventional technology Communication of the ECUs are not used. Accordingly  had to have a variety of communication networks for different methods of communication are provided, when used for each of the ECUs. Accordingly the wiring system was particularly complicated for that Communication network of the ECU on a vehicle is appropriate, and cost to manufacture the Communication network were increased.

Furthermore, there was a problem in that when the Communication data to an ECU to control an engine Vehicle that was not in communication involved that the ECU could work erroneously, so that's a difficulty driving the vehicle was caused.

The object of the invention is a communication network to provide, in which a faulty operation of ECUs in a communication network prevented during communication becomes.

This task is solved with a communication network according to Claim 1. There are independent between the respective ECUs Communication lines formed, with first and second communication method depending on one Switching state of the isolating or switching device used become. Use these different communication methods different command formats.

Further advantageous embodiments and improvements of Invention are specified in the subclaims. below the invention is based on its embodiments Reference to the drawing explained in more detail. In the Show drawing:

Fig. 1 is a block diagram to show a first embodiment of the present invention;

Fig. 2 shows a timing for showing communication data in the first embodiment of the present invention;

FIGS. 3a and 3b are diagrams showing the communication method with the first embodiment of the present invention;

Fig. 4 is a block diagram showing the second embodiment of the present invention;

Fig. 5 is a timing chart showing the communication data in the second embodiment of the present invention;

Fig. 6 is a block diagram showing a third embodiment of the present invention;

Fig. 7 is a block diagram showing a fourth embodiment of the present invention;

Fig. 8 is a block diagram showing a fifth embodiment of the present invention;

Fig. 9 is a block diagram of a conventional communication network goats.

Preferred embodiments of the present invention are described below with reference to the drawings described.

Fig. 1 is a block diagram to show the first embodiment of the present invention, and Fig. 2 is a timing chart to show communication data which is sequentially transmitted or received by each ECU. In Figs. 1 and 2, reference numeral 1 denotes an ECU including as a vehicle control means of a switching device 104 which is controlled by a control signal which is output from an output port Po. The ECU1 serves as a main computer for controlling communication. As a typical ECU mounted on a vehicle, there are a control device for controlling the start of the engine, a control device for controlling the fuel injection amount, a control device for preventing theft of the vehicle, a device for preventing theft of an audio device that is provided in the vehicle, or the like.

Reference numerals 32 , 33 and 34 denote ECUs as vehicle control devices which are similar to those shown in FIG. 9. A CPU 101 is installed in the ECU 1 , which is provided with an output port Tx, an input port Rx and an output port Po for outputting a control signal which controls a switching circuit 104 . The CPU can calculate data for transmission and output thereof and calculate received data as a digital code. The ECU 1 is further provided with a transmission-only interface 102 as a communication device and a reception-only interface as a communication interface. The reference numerals 41 and 42 denote communication lines as bus bars. The switching device 104 serves to connect and interrupt the communication line 42 . The switching device 104 is included in the ECU 1 . A letter B in Fig. 1 denotes branch portions from which each transmission-only interface and each reception-only interface are branched off.

The communication system used in the network shown in Fig. 1 is an asynchronous half-duplex communication system. Accordingly, the communication lines 41 , 42 are shared for transmitting and receiving data. Furthermore, each of the ECUs can serve as a main computer (a communication control device).

The operation of the communication network is as follows described.

First, a control signal is output from the output port Po of the CPU 101 in the ECU 1 . When the switch 104 is in a closed state (indicated by a letter J in FIG. 2), the communication line 42 is connected to the ECU1. Data ( 1 ) 200 is transmitted through the output port Tx of the CPU 101 in the ECU 1 . Then, the data (1) 200 at the input port Rx is received by each CPU in the ECUs 1 , 32 , 33 , 34 .

When data (2) 201 is transmitted through the gate Tx of the CPU 321 of the ECU 32 in response to the data (1) 200 , the data (2) 201 is transmitted through the gate Rx of each of the CPUs in the ECUs 1 , 31 , 33 , 34 received.

When the switching circuit 104 is in an open state (which is denoted by a letter K in FIG. 2) by receiving a control signal output through the gate Pu of the CPU 201 in the ECU 1 , the communication line 40 is in a disconnected state from the ECU 1 . Accordingly, when data (3) 202 is transmitted through the gate Tx of the CPU 201 in the ECU, the data (3) 202 is received only through the gate Rx in each CPU of the ECUs 1 , 32 and the data (3) 202 becomes not received by each CPU of the Ecus 33 , 34 through the Rx gate.

When data (4) 203 is transmitted through the gate Tx of the CPU 321 in the ECU 32 in response to the data (3) 202 , the data (4) 203 is received and only through the gate Rx of each CPU of the ECUs 32 , 1 the data (4) 203 is not received by each CPU of the ECUs 33 , 34 through the gate Rx.

In the event that the switch circuit 104 is in an open state and the data (5) 204 is transmitted through the gate Tx of the CPU 331 in the ECU 33 , the data (5) 204 through the gate Rx of each CPU of the ECUs 33 , 34 received. However, data ( 5 ) 204 is not received by the gate Rx of each CPU in the ECUs 1 , 32 .

Further, when data (6) 205 is transferred through the gate Tx of the CPU 341 in the ECU 34 in response to the data on the data ( 5 ) 204, the data (6) 205 is transferred through the gate Rx of each CPU of the ECUs 33 , 34 received. However, the data (6) 205 is not received by each CPU of the ECU 1 , 32 through the gate Rx.

As described above, when the switching circuit 104 is opened to perform communication only between the ECUs 1 , 32 , the communication data from the ECUs 1 , 32 are not transmitted to the ECUs 33 , 34 . Accordingly, the ECUs 33 , 34 are not affected by communication data from the ECUs 1 , 32 .

Furthermore, if the communication is performed only between the ECUs 33 , 34 , no communication data is transmitted from the ECUs 33 , 34 to the ECUs 1 , 32 . Accordingly, the ECUs 1 , 32 are not affected by the communication data from the ECUs 33 , 34 . Namely, communication between a group of ECUs 1 , 32 and a group of ECUs 33 , 34 is prevented.

Furthermore, since an independent communication line is formed between the ECUs 1 , 32 while communicating with each other, it is possible to use different communication at the same time.

Use of various communication methods in the first embodiment will be described below. For example, when the switching circuit 104 in the ECU 1 is in a closed state, namely, the communication line 42 is in a connection state, a 1-bit command response type communication method can be used as a communication method that is shared among each CPU, such as shown in Fig. 3a. On the other hand, when the switch circuit 104 is in an open state, namely, the communication line 42 is in a disconnected state, a 3-bit command response communication method can be used as a communication method only between the ECU 1 and the ECU 32 , as shown in Fig. 3b , In this case, the CPU 101 in the ECU 1 and the CPU 321 in the ECU 32 are each configured to respond to both communication methods of the 1-bit command response type and the 3-command response type.

In the first embodiment, since the switching circuit 104 is installed in the ECU 1 , assembling the ECU to a vehicle can be easy.

The second embodiment of the present invention will describe below.

FIG. 4 is a block diagram illustrating the second embodiment, and FIG. 5 is a timing chart for illustrating the communication data transmitted and received by each of the ECUs in a time sequential manner.

Reference numerals 51 , 52 , 53 and 54 denote ECUs as control means for controlling a vehicle or communication means, and reference numerals 511 , 521 , 531 and 541 denote CPUs. Reference numerals 512 , 522 , 532 and 542 denote transmission-only interfaces as a transmission device; reference numerals 513 , 523 , 533 and 543 denote receive-only interfaces as a receiving device, and reference numerals 60 , 61 , 62 and 63 denote communication lines as first and second bus bars. The communication line has a duplex communication line structure, wherein a set of the communication network with two communication lines is only available for transmission and only for reception. Reference numerals 514 , 515 , 516 and 517 denote switches as switching devices and changing devices. Each of the CPUs 511 , 521 , 531 , 41 is provided with an output port Tx and an input port Rx. The CPU 511 is also provided with an output port Po.

In the first embodiment mentioned above, that half-duplex asynchronous communication system used. On the other hand, in the second embodiment, a asynchronous duplex communication system used.

The operation of the second embodiment is as follows described.

First, a control signal is output through the output port Po of the CPU 511 in the ECU 51 . When the switching circuits 514 , 515 , 516 , 517 are in a state in which the terminals cb are connected as shown in Fig. 4 (such a state is indicated by a letter L in Fig. 5), the connection between the Communication line 60 and the CPU 511 of the ECU 51 are established and the connection between the communication line 61 and the CPU 511 of the ECU 51 is established. Namely, there is such a state of connection that the ECU 53 serves as a main computer and the ECUs 51 , 52 and 54 serve as a user computer. In this case, data (1) 601 is transmitted through the gate Tx of the CPU 531 in the ECU 53 , and data (1) 601 is received through the gate Rx from each CPU of the ECUs 51 , 52 , 54 .

Further, when data (3) 602 is transmitted through the gate Tx of the CPU 541 in the ECU 54 in response to the data ( 1 ), the data (2) 602 is received through the gate Rx of the CPU 531 of the ECU 53 .

Next, a case will be described in which a control signal is output through the output port Po of the CPU 511 in the ECU 51 and the switching circuits 514 , 515 , 516 , 517 are each brought into a state in which terminals ca are connected (to a Letter M in Fig. 5). Then, the connection between the communication line 60 and the CPU 511 in the ECU 51 is broken, and communication between the communication line 61 and the CPU 511 in the ECU 51 is broken.

Furthermore, the transmission-only interface 512 in the ECU 51 goes into a connection state with the reception-only interface 523 in the ECU 52 via the communication line 63 , and the reception-only interface 513 in the ECU 51 takes a connection state with it the transmission-only interface 522 in the ECU 52 via the communication line 62 . Accordingly, 2 communication networks are formed: a communication network with the ECU 53 as a main computer and the ECU 54 as a user computer, and a network with the ECU 51 as a main computer and the ECU 52 as a user computer.

In the structure shown in FIG. 4, when data in (3) 603 is transmitted through the gate Tx of the CPU 511 in the ECU 51 , the data ( 3 ) 603 is received only through the gate Rx of the CPU 521 in the ECU 52 , and the data ( 3 ) 603 are not received by the gate Rx of each CPU in the ECUs 53 , 54 . Further, when data (4) 604 is transmitted through the gate Tx of the CPU 521 and the ECU 52 , the data (4) 604 is received only through the gate Rx of the CPU 511 in the ECU 51 , and data (4) 604 only through the gate Rx of the CPU 611 of the ECU 51 is received, and the data (4) 604 is not received by the gate Rx of each CPU in the ECUs 53 , 54 .

In the above-mentioned case, when data (5) 605 is transmitted through the gate Tx of the CPU 531 and the ECU 53 , the data (5) 605 is received only through the gate Rx of the CPU 541 in the ECU 54 and the data (5) 605 are not received by each CPU of the ECUs 51 , 52 through the gate Rx.

When data (6) 606 is received by the gate Tx of the CPU 541 in the ECU 54 in response to the data ( 5 ) 605, the data ( 6 ) 606 is received only by the gate Rx of the CPU 531 in the CPU 53 , and the data (6) 606 is not received by the gate Rx of each CPU of the ECUs 51 , 52 .

As described above, in the case where the switches 514 , 515 , 516 , 517 are respectively brought into a connection state between the terminals ca, and communication is only performed between the ECU 51 and 52 , the communication data can be transmitted from the ECUs 51 , 52 to the ECUs 53 , 54 can be prevented, and transmission of the communication data from the ECUs 53 , 54 to the ECUs 51 , 52 can be prevented.

Furthermore, a communication method between the ECUs 51 , 52 may be different from that between the ECUs 53 , 54 .

Since the switches 514 , 515 , 516 , 517 are included in the ECU 51 , assembly work for a vehicle can be easy.

The third embodiment of the present invention will described below.

Fig. 6 is a block diagram for illustrating the third embodiment of the present invention. In Fig. 6, reference numeral 71 denotes a failure diagnosis tester as a failure diagnosis control device which has a CPU 711 with a function as a failure diagnosis effecting device, as well as a transmission-only interface 712 and a reception-only interface 713 . In general, the failure diagnosis tester for a vehicle is connected to the vehicle in, for example, a dealership or the like when the vehicle is subjected to diagnosis to find a failure. Numeral 72 denotes a test detection line for detecting whether the failure diagnostic tester is connected or not. Reference numeral 73 denotes a connector for diagnosis, which connects the failure diagnosis tester 71 with the test detection line 72 and a communication line for diagnosis 75 (which will be described later). A communication line 74 for failure diagnosis of each ECU 81 , 82 , 83 or 84 each with a CPU 811 , 821 , 831 or 841, a transmission-only interface 812 , 822 , 832 or 842 and a reception-only interface 813 , 823 , 833 or 843 is connected between the ECUs 81 and 82 . Furthermore, the ECU 81 has a switching circuit 814 .

Each of the CPUs 811 , 821 , 831 , 841 is provided with an output port Tx and input ports Rx and Pi. Furthermore, the CPU 811 is provided with an output port Po.

The operation of the third embodiment is as follows:

When the failure diagnostic tester 71 is in a non-connection state, the test detection line 72 is not grounded, and accordingly, the test detection line 72 is in a high potential state. Then, the input port Pi in each of the CPUs 811 , 821 , 831 , 841 in the ECUs 81 , 82 , 83 , 84 detects that the electrical potential of the test detection line 72 is in a high potential state (hereinafter referred to as logic 1).

In this case, when the CPU 811 in the ECU 81 detects the logic 1 at the input port P1, a control signal which sets the switching circuit 815 in an open state is output by the output port Po. Accordingly, the ECU 81 is disconnected from the failure diagnosis communication line 75 . Then, communication is only allowed between the ECU 81 and the ECU 82 via the failure diagnosis communication line 74 , so that the communication is carried out only between the ECUs 81 , 82 .

When the failure diagnosis tester 71 is connected to the diagnosis tester 73 , the test detection line 72 shows a low potential state because the test detection line 72 is connected to the ground within the failure diagnosis tester 71 . Accordingly, the input port Pi in each of the CPUs 811 , 821 , 831 , 841 detects that the electrical potential of the test detection line 72 is in a low potential state (hereinafter referred to as logic 0).

At this moment, each of the CPUs 811 , 821 , 831 , 841 recognizes a waiting condition of the communication for diagnosis, and the ECU 81 outputs a control signal through the output port Po for closing the switching circuit 104 , whereby communication data for diagnosis output from the failure diagnosis tester 71 can be transmitted to the ECU 81 and the ECU 82 .

As described above, in the third embodiment, when the failure diagnosis tester 71 is in a disconnected state, the communication between the ECU 81 and the ECU 82 using the communication line for diagnosis 74 can be effectively used.

A switching circuit can be provided in the test detection line 72 for connecting the line 72 to the diagnostic connector 73 or for decoupling it. In this case, the input port Pi detects the logic 1 by putting the switch circuit in a closed state even though the failure diagnosis tester 71 is connected, whereby communication is only allowed between the ECU 81 and the ECU 82 using the communication line for diagnosis 74 . Furthermore, the failure diagnosis can be carried out if the switching circuit which is arranged in the test detection line 82 is switched by a signal from the failure diagnosis tester 71 .

The fourth embodiment of the present invention will described below.

In the above-mentioned embodiments, general use of ECUs has been described. This embodiment specifically describes ECUs used in a vehicle. For example, in FIG. 6, it is assumed that the ECU 81 is an anti-theft prevention vehicle that functions as an anti-theft control device and the ECU 82 is an engine control ECU that functions as a control device the start of the engine works. In this embodiment, the communication line for diagnosis 74 , which may not be used frequently, can be used as a communication line for a vehicle theft prevention system (a system in which communication of data is effected between the vehicle theft prevention ECU and the engine control ECU) ) are used, and the starting of the engine is prevented or permitted by coincidence of code elements).

The fourth embodiment will be described below with reference to FIG. 6.

When the failure diagnostic tester 71 is in a non-connection state, the potential of the test detection line 72 is in a high potential state, so that the input port Pi of each of the CPUs 811 , 821 , 831 , 841 in the ECUs 81 , 82 , 83 , 84 is in a logic state 1 recorded. At this moment, since the switching circuit 814 is in an open state, communication is independently permitted between the ECU 81 (the vehicle theft prevention ECU) and the ECU 82 (the engine control ECU). Then an engine start signal is generated by a special communication procedure.

When the failure diagnostic tester 71 is connected to a diagnostic connector 73 , the test detection line 72 is connected to the ground within the failure diagnostic tester 71 . Then, the test detection line 72 goes low, and the input port Pi of each of the CPUs 811 , 821 , 831 , 841 detects a logic 0 state. At this moment, each of the CPUs 811 , 821 , 831 , 841 detects a waiting state of diagnostic communication and sets the switch 814 in the vehicle theft prevention ECU 81 to a closed state, whereby communication data for diagnosis can be transmitted to the ECU 81 (the vehicle theft prevention ECU) and the ECU 82 (the engine control ECU).

As described above, in the present invention, the communication line for diagnosis 74 , which was not used when the engine was started, can be used as a communication line for the vehicle theft prevention system.

Furthermore, there is a case that an ECU mounted on a vehicle does not include RAM, ROM, etc. In this case, switch 814 can only be opened when the engine is started. On the other hand, a RAM or ROM located outside the ECU can be used.

The fifth embodiment of the present invention will described below.

Fig. 7 is a block diagram for illustrating a fifth embodiment. In Fig. 7, reference numerals 91 , 92 , 93 and 94 denote CPUs. Each of the ECUs 91 , 92 , 93 , 94 has a CPU 911 , 921 , 931 and 941 , respectively. Each of the CPUS 911 , 921 , 931 and 941 is provided with output ports Tx and Po and an output port Rx. The ECUs have transmission-only interfaces 912 , 922 , 932 , 942 and reception-only interfaces 913 , 923 , 933 , 943 .

The reference numerals 914 , 924 , 934 denote switching devices (switches) for opening and closing communication lines 95 , 96 , 96 . The switch 924 serves as a switching device for switching the communication line connected to the ECU 92 . Furthermore, it decouples the ECU 92 from the communication line 95 and connects it to a further communication network 98 .

Furthermore, the CPU 921 is designed to change an internally used communication method in accordance with the switching of the communication line by the switching circuit 924 .

The operation of the fifth embodiment is as follows:

When the switches 914 , 934 are each closed and the switch 924 is connected to connect the communication line 95 to the ECU 92 , the ECUs 91 , 92 , 93 , 94 operate as a group of a communication network and carry out mutual communications.

When the switch 924 is operated to connect the ECU 92 to the communication line 95 , the switching circuit 934 is closed and the switching circuit 914 is opened, two groups of communication networks are formed: a communication network with the ECUs 91 , 92 and a communication network with the ECUs 91 , 93 , 94 . Accordingly, mutual communication can be carried out independently in the groups of communication networks.

When the switch 94 is switched to the side of another communication network 98 , the ECU 92 can be used for the other communication network 98 .

As described above, in accordance with the fifth embodiment communication networks in desirably by operating the switching devices using common communication lines are formed, reducing the number of Communication lines and the transmission-only and Receiving interfaces can be reduced.

The sixth embodiment of the present invention will described below.

Fig. 8 is a block diagram for illustrating the sixth embodiment. In Fig. 8, reference numerals 55 and 56 denote ECUs in which CPUs 551 , 561 transmission-only interfaces 552 , 562 and reception-only interfaces 553 , 563 are provided. Each CPU 551 , 561 has output gates Tx and Po and an input gate Rx. The reference number 554 , 564 is designed as a switching device for connecting a communication line 64 or 65 to a communication line 66 or 67 and separating the previous one from the latter. The construction other than the above is the same as that of the second embodiment, and the same reference numerals are used for the same elements, and a description of these elements is omitted.

The operation of the sixth embodiment is as follows.

When the switching circuit 564 is in an open state (as shown in FIG. 8), the switching device 554 connects the transmission-only interface 552 to the communication line 65 and connects the reception-only interface 553 to the communication line 64 (as in FIG . 8). In this case, the ECU 56 serves as a main computer, and two communication networks are formed: a group of a communication network in which the ECU 56 serves as a main computer and the ECU 54 serves as a user computer, and another group of a communication network in which the ECU 55 serves as a main computer and the ECUs 52 and 53 serve as a user computer.

When the switch 564 is closed, the switch 554 connects the transmission-only interface 552 to the communication line 64 and connects the reception-only interface 553 to the communication line 65 . In this case, a single communication network is formed in which the ECU 56 serves as a main computer and the ECUs 52 , 53 , 54 , 55 serve as a user computer.

As described above, even in this embodiment using the asynchronous duplex communication system Communication networks capable of forming various Structures are formed using common communication lines in the same way and Way as in the other embodiments, and accordingly, the number of communication lines and transmission-only and reception-only interfaces be reduced.  

In a communication network that is on the vehicle can be attached in the above Described embodiments, the communication data to an ECU or ECUs for which the Communication data are required.

Accordingly, erroneous operation of the ECU or of the ECUs can be prevented and the vehicle can be in one be kept in a safe state.

In some embodiments, the switching circuit is or -circuits arranged in the ECU. However, they can be located outside the ECU. Furthermore, the Switching circuits can be arranged within an ECU.

In the above-mentioned embodiments, a mechanical switch can be used for the switch. Furthermore, an electromagnetic relay or analog multiplexer or the like as the switching circuit to be used.

In some cases of the above-mentioned embodiments, in which the half-duplex asynchronous communication system is used, the branch section between the transmission-only interface and the reception-only interface (for example, the branch section is indicated by B in FIG. 1) in FIG ECU included. However, the branch section can be provided outside the ECU.

In the above-mentioned embodiments, there is a case that part of the communication line, which is common is used, is arranged inside the ECU. However, can a part of the communication line which is outside the To be arranged to be arranged within the ECU.

In the above-mentioned embodiments, a Control signal output from the CPU in an ECU  used as a signal to operate the switching device. However, another signal, e.g. B. a signal to Starting the engine of a vehicle can be used.

In the above-mentioned embodiments, the ECUs are called Vehicle control devices used. However, any appropriate facilities as long as they are a control facility with a communication function can be used. Furthermore, an ECU can be used without involving the CPU become.

The embodiments are asynchronous Half-duplex communication method or asynchronous Duplex communication method described. However, one other communication system can be used.

The embodiments are based on a 1-bit command Answer type or a 3-bit command response type explained. However, another communication system can be used. Furthermore, a communication system with a different communication protocol can be used.

Claims (12)

1. Communication network for controlling a vehicle, comprising:

• a) a plurality of vehicle control devices ( 32 , 33 , 34 ) each with a CPU ( 321 , 331 , 341 );
• b) a main control device ( 1 ) with a CPU ( 101 );
• c) a first communication link ( 41 ) for connecting the CPU of the main control device ( 1 ) to a first group of the vehicle control devices ( 32 , 33 , 34 );
• d) a second communication link ( 42 ) for connecting a second group of vehicle control devices ( 32 , 33 , 34 ); and
• e) a switching device ( 104 ) controlled by the CPU ( 101 ) of the main control device ( 1 ) which, in a closed state, connects the CPU ( 101 ) of the main control device ( 1 ) to the second communication link ( 42 ) and in one separates the open state from it; in which
• f) when the switching device ( 104 ) is in its closed state, all CPUs ( 321 , 101 , 331 , 341 ) jointly use a first communication method (1-byte) with a first command format for data exchange; and
• g) when the switching device ( 104 ) is in its open state, the CPUs ( 331 , 341 ) of the second group use the first communication method (1 byte) for data exchange and the CPU ( 101 ) of the main control device ( 101 ) and the CPUs (e.g. 321 ) of the first group use a second communication method (3-byte) with a second command format for data exchange.

2. Communication network according to claim 1, characterized in that

• a) the CPUs are each provided with an output port (Tx) or an input port (Rx), which have the input of a send-only interface ( 322 , 332 , 342 ) or the output of a receive-only interface ( 323 , 333 , 343 ) are connected.

3. Communication network according to claim 2, characterized in that

• a) the output of the send-only interface ( 322 , 332 , 342 ) and the input of the receive-only interface ( 323 , 333 , 343 ) are connected to a branch point (B);
• b) the first communication link ( 41 ) connects the branch point (B) of the main control device ( 1 ) to the branch points (B) of the first group of vehicle control devices ( 32 , 33 , 34 );
• c) the second communication link ( 42 ) connects the branch points (B) of the second group of vehicle control devices ( 32 , 33 , 34 ); and
• d) the controlled switching device ( 104 ) in the closed state connects the branch point (B) of the main control device ( 1 ) to the second communication link ( 42 ) and disconnects in an open state.

4. Communication network according to claims 1-3, characterized in that an asynchronous half-duplex data exchange method ( Fig. 3) is used for data exchange. 5. Communication network according to claim 2, characterized in that

• a) the first communication link ( 41 ) comprises two communication lines ( 63 , 62 );
• b) the second communication link ( 42 ) comprises two communication lines ( 60 , 61 );
• c) the switching device ( 104 ) comprises two switching units ( 516 , 517 ) and two switching units ( 514 , 515 );
• d) wherein the first and second communication line ( 63 , 62 ) of the first communication connection the input of the receive-only interface ( 523 ) or the output of the transmit-only interfaces ( 522 ) of the vehicle control devices ( 52 ) of the first group with a first or second switching unit ( 514 , 515 ) connects;
• e) the first or second communication line ( 60 , 61 ) of the second communication connection being the output of the transmit-only interfaces ( 532 , 542 ) or the input of the receive-only interface ( 533 , 543 ) of the vehicle control devices ( 53 , 54 ) connects the second group to a first and second switching unit ( 516 , 517 );
• f) wherein the first switching unit ( 516 ) in its closed state (cb) connects the first communication line ( 60 ) of the second communication link ( 60 , 61 ) to the output of the send-only interface ( 512 ) of the CPU of the main control device ( 51 ) and (ca) separates from it in its open state;
• g) wherein the second switching unit ( 517 ) in its closed state (cb) connects the second communication line ( 61 ) of the second communication link ( 60 , 61 ) to the input of the receive-only interface ( 513 ) of the CPU of the main control device ( 51 ) and (ca) separates from it in its open state;
• h) the first switching unit ( 514 ) in its first switching state (cb) connecting the first communication line ( 63 ) of the second communication connection ( 63 , 62 ) to the input of the receive-only interface ( 513 ) of the CPU of the main control device ( 51 ) and in its second switching state (ca) connects the first communication line ( 63 ) of the second communication link ( 63 , 62 ) to the output of the send-only interface ( 512 ) of the CPU of the main control device ( 51 );
• i) wherein the second switching unit ( 515 ) in its first switching state (cb) connects the second communication line ( 62 ) of the second communication link ( 63 , 62 ) to the output of the send-only interface ( 512 ) of the CPU of the main control device ( 51 ) and in its second switching state (ca) connects the second communication line ( 63 ) of the second communication link ( 63 , 62 ) to the input of the receive-only interface ( 513 ) of the CPU of the main control device ( 51 ); and
• j) wherein the CPU ( 511 ) of the main control device ( 51 ) switches the first and second switching units ( 516 , 517 ) and the first and second switching units ( 514 , 515 ) simultaneously in their closed or open and first and second switching states ,

6. Communication network according to claim 5, characterized in that an asynchronous duplex data exchange method ( Fig. 5) is used for data exchange. 7. Communication network according to claim 1, characterized in that a failure diagnosis tester ( 71 ) with a CPU ( 711 ) is provided, which is connected to the second communication connection ( 75 ) via a diagnosis connector ( 73 ), the CPUs ( 821 , 831 , 841 ; 811 ) of the vehicle control devices ( 82 , 83 , 84 ) and the main control device ( 81 ) each comprise a test input (Pi) which is connected to a test detection line ( 72 ) which is connected via the diagnostic connector ( 73 ) is connected to the failure diagnosis tester ( 71 ). 8. Communication network according to claim 7, characterized in that

• a) the CPU of the failure diagnosis tester ( 71 ) is provided with an output port (Tx) or an input port (Rx), which with the input of a send-only interface ( 322 , 332 , 342 ) or the output of a receive-only interface ( 323 , 333 , 343 ) are connected.

9. Communication network according to claim 7, characterized in that when the failure diagnosis tester ( 71 ) via the connector ( 73 ) with the second communication connection ( 75 ) is or is not connected, the test detection line ( 72 ) on a first or second Potential ("1" or "0"), the switching device ( 814 ) being controlled by the CPU ( 811 ) of the main control device ( 81 ) in the open or closed state. 10. Communication network according to claim 7, characterized in that
a vehicle controller ( 82 ) of the first group controls starting the engine of the vehicle; and
the main control device ( 81 ) controls an anti-theft device of the vehicle. 11. Communication network according to claim 1, characterized in that between the vehicle control devices (z. B. 93 , 94 ) of the second groups in each case further switching devices (z. B. 934 ) are installed in the second communication connection ( 97 ) by of the respective CPU (e.g. 931 ) of the vehicle control device in order to define further subgroups of vehicle control devices in the second group. 12. Communication network according to claim 1, characterized in that in the first group of vehicle control devices, the one switching unit ( 924 ) between the first communication link ( 95 ) and a vehicle control device ( 92 ) is provided, which controls this, the switching unit ( 924 ) connects the vehicle control device ( 92 ) to a further communication network ( 98 ) in a first switching state and disconnects it from the first communication connection ( 95 ) and connects the further communication network ( 98 ) to the first communication connection ( 95 ) in a second switching state and disconnects from the vehicle control device ( 92 ).