DE3147550A1 - Loop-data transmission system for a motor vehicle - Google Patents

Abstract

A loop-data transmission system for a motor vehicle has at least one ring transmission line, one main station and a plurality of sub-stations. Each of the substations is connected to at least one electrical load or measuring sensor of the motor vehicle and has a logic circuit for logically adding information, which is received from the sensor connected to it, to the information received via the transmission line, by which means output information for transmission to the main station via the transmission line is generated.

Description

Loop data transmission system for a motor vehicle

The invention relates to a loop data transmission system, in which a master station and several slave stations are used to transmit and process the data are connected by means of a closed loop or ring line. In particular the invention relates to a loop data transmission system for use in motor vehicles.

Conventionally, in a motor vehicle, data were about one another transmit independent lines that were intended for the respective data. In modern motor vehicles that are equipped with a variety of electronic or

electrical facilities are equipped, therefore results in the increase of data an increase in the number of transmission lines, causing problems regarding of weight and space occupied.

To remedy the shortcomings inherent in the prior art it has been proposed to use a loop data transmission system in motor vehicles use, in which several slave stations and a master station with each other by means of a closed loop or ring line are connected to this data to be transmitted in time division multiplexing. Although the system of this kind is general has been used in the field of messaging, it can be assumed, however, that various difficulties arise when this system in a motor vehicle is used. For example, it can be considered for installation in the motor vehicle to draw that the stations and especially the secondary stations are subjected to high loads exposed to vibrations, heat, pollution and the like that are likely lead to trouble. If difficulties arise, it is likely that the entire data transmission system is disturbed because it is the loop or. Ring structure Has. Furthermore, when used in motor vehicles, the response and control sequence can be carried out quickly depending on a change in operating conditions. Therefore, in comparison with the use of the system of this type in the field of Messaging reduces the time it takes to transmit data will. Furthermore, since life resp.

the health of the occupants to a large extent on the controllability of the motor vehicle, any error must be reliably detected that arises during data transmission.

The invention is based on the object of a loop data transmission system for automobiles, in which if difficulties arise at any Part of the system is not the same as the whole system is disturbed.

The invention also aims to provide a loop data transmission system for motor vehicles are created with which information can be transmitted quickly are in order to achieve a quick response with regard to the function of the motor vehicle.

Furthermore, with the data transmission system according to the invention, the Motor vehicle be safely controllable.

The loop data transmission system according to the invention for a motor vehicle, that many electrical consumers and transmitters or sensors for controlling various Functions of the motor vehicle and / or to determine different operating states des KraftfahrzeUgs has at least one ring transmission line, one on the Transmission line arranged main station for sending information intended for Control of electrical loads are used and for receiving over the transmission line transmitted information, and a plurality of on the Transmission line slave stations arranged in series for receiving the transmitted Information about the transmission line and for sending output information over the transmission line, each of the slave stations at least one the electrical consumer and / or encoder is assigned and a logic circuit with the information received from the connected electrical Information received from the encoder can be added logically, whereby the output information be generated.

The invention is described below using an exemplary embodiment Referring to the drawing explained in more detail.

Fig. 1 is a block diagram schematically showing an embodiment of the data transmission system illustrated.

FIG. 2 is a block diagram showing a slave station shown in FIG shows.

Fig. 3 is a flow chart showing part of control programs a main station illustrated.

Fig. 4 shows the internal format of information trapped in the System according to the embodiment of FIG. 1.

Figs. 5 and 6 are flow charts showing part of control programs the substation illustrate.

Fig. 1 is a block diagram schematically showing the overall structure of an embodiment of the data transmission system, shows in which 10 a The main station is built into a central control unit of the motor vehicle is, and 12, 14 and 16 are substations in different parts of the motor vehicle are built in. The master station 10 and the slave stations 12, 14 and 16 are in Row to each other with a loop.

a ring of bidirectional cables such as fiber optic cables tied together. The bidirectional loop lines are used between the main station 10 and the slave stations 12, 14 and 16 sent and received data. To the main station 10, a display device 18 is connected, which is attached to one place is easy to access by the driver of the motor vehicle see is. At the main station 10 and the secondary stations 12, 14 and 16 are sensors or transmitters and consumers connected. For example, there is a relay contact at the secondary station 12 20 connected. For example, attached to the slave station 14 is a transducer 22 of the embodiment with variable resistance, an electromagnet coil 24 and a lamp 26 connected, while at the secondary station 16, for example, a transducer 28 of the execution with variable resistor, a switch 30, a servo motor 32 and a lamp 34 connected are. On receipt of the from the main station 10 over the loop lines transmitted data towards each of the secondary stations controls the consumers and sends in response to a command from the main station 10 by means of 'the encoder of the Slave stations acquired data on master station 10.

Fig. 2 is a block diagram showing the structure of a slave station shows, at 40a and 40b transmission lines consisting of fiber optic cables which form a loop in one direction while with 42a and 42b denotes transmission lines consisting of fiber optic cables that form a loop or ring line in the opposite direction. About the light guide 40a and 42a transmitted optical or light signals are from photoelectric Transducers 44 and 46 received and converted into electrical signals. The output signals the photoelectric converters 44 or 46 are converted into serial-parallel converters (input buffer) 48 or 50 are entered, where they are converted into parallel data. on the other hand the output signals of the photoelectric converters 44 and -46 via an OR gate 52 and 54 are fed directly to electro-optical converters 56 and 58, respectively, where they are converted into light signals implemented and via the light guides 40b and 42b to the next Slave station or the master station. Parallel output connections of the Serial-parallel converters 48 and 50 are equipped with data input connections IN1 and IN1.

IN2 of a microprocessor 60 connected. Data output terminals OUT1 and OUT2 of the microprocessor 60 are connected to parallel input connections of parallel-to-serial converters (Output buffers) 62 and 64 connected. Therefore, the data from the microprocessor 16 The parallel data output is converted into serial data by the converters 62 and 64, via the OR gates 52 and 54 to the electro-optical converters 56 and 58, respectively be created.

The serial data is then sent through the electro-optical converter 56 and 58 converted into light signals which are transmitted via the light guides 40b and 42b, respectively will.

Determination data generated by the encoders connected to the extension or measurement signals are sent to the microprocessor 60 via input interfaces (not shown) such as buffers and analog-to-digital converters and supplied via lines 66. The microprocessor 60 generates control signals via lines 68 and via output interfaces (not shown) and driver circuits supplied to the consumers connected to the secondary station will. Furthermore, a fixed memory is connected to the microprocessor 60 via a bus line 70 (ROM) 72, a random access memory or random access memory (RMi) 74 and a Timer 76 connected. In the read-only memory 72 is a control program for the Microprocessor 60 stored. After this saved program, the Operations of the microprocessor 60 and the slave station are controlled.

The main station 10 shown in Fig. 1 can from the slave station 2 are formed in that lines 78 and 80 and the OR gates 52 and 54 are omitted and the output signals of the parallel-serial converters 62 and 64 are applied directly to the electro-optical converters 56 and 58, respectively. In In this case, a program for controlling the main station is stored in the read-only memory 72 saved. Fig. 3 is a flow chart showing an example of the program for controlling the main station illustrated. In the following, with reference to Fig. 3 the mode of operation of the main station 10 is described.

When the ignition switch of the automobile is turned on; in order to put the entire data transmission system into operation, the system prepared at a step 100 of FIG. It is then determined in a step 101, whether a point in time for sending a start bit to the counterclockwise loop and to the Clock hand loop is present. If it is determined that there is a point in time, at that by means of an interrupt signal. the timer 76 the start bit in each the loop is to be sent, in a next step 102 the start bit is in sent the loops for both directions'. Then will be with a next one Step 103 - an address word and an index word are sent. The address word denotes the individual end devices such as the encoders connected to the secondary stations or Consumer, while the index word is the content or the type of processing to the Terminals determines, namely prescribes whether to retrieve data from the terminals or whether the end devices have to perform a certain work process. at a step 104 is determined sets whether in the main station 10 Output data are available.

If there is no output data, the program advances to a step 105, both transmit the output "O" to the output buffers will. If there is output data, the program proceeds to a step 106, in which the output data stored in the read / write memory 74 are sent to the converters (Output buffers) 62 and 64 are transferred. The next step is to determine whether the time corresponds to that for the processing or transmission of the data, namely whether there is a data area in a data block.

This time determination is also made using the signal from the Timer 76 controlled. When the time has come to process the data, the program advances. to a step 108. In step 108 it is decided whether the time is at which the data is sent from the main station should or not. When the transmission operating time is determined, a Next step 109 loops the data from output buffers 62 and 64 submitted. Thereafter, at step 110, the address word and the index word become prepared for the next data block, after which the program goes to step 101 returns. If it is determined in step 108 that there is no transmission operation time is established, the program proceeds to a step 111. At step 111 it is determined 'whether data are to be received from the terminal of the slave station.

When a reception operating time is determined, the program advances to a step 112, in which the data sent over the loops from the Input buffers 48 and 50 are included. The received data are further processed ir the read / write memory 74 is stored. At a step 113, a subprogram is made. to check the receipt of data. This subpro- gram will be described in detail later. If at.

it is determined in step 111 that no data is to be received, the program proceeds to step 110. In other words, there will be none in this case Data sent or received.

From the above description it can be seen that in the data transmission system the time division multiplex system is used and the start-stop system is used as the synchronization system is used.

Fig. 4 shows a data format of the data transmission system, wherein a is a start bit with the logic level "1", b is the area of an address word and c is the area of an index word. The areas of the start bit a, the address word b and the index word c can only be determined by the main station. In 4, d is also the time required at the secondary stations for the decoding the address word and the index word and the transfer of the data from the read / write memory to the output buffer or a Lee ^> it area (logic level "O") for the adjustment the time required by the master station in the read / write memory transfer the contained data to the output buffer; e is an area in which the data is inserted from the master station to the slave stations or vice versa be transmitted; f is a parity bit.

g is a stop bit; a 'is a start bit of the next data block. As is known, the range of the stop bit g has the logic level "O". With this one Embodiment, however, the number of stop bits g was chosen so that they is greater than the number of bits from the start bit a to the parity bit f. In the data transmission system described, therefore, if one of the Start bit incorrectly different bit as Start bit recognized the error can be easily corrected after a period of one data block has elapsed. In this way, an error can be detected immediately in this data transmission system and corrected, what for data transmission systems used in motor vehicles is of great importance.

Fig. 5 is a flow chart of a program for controlling the Secondary station. The function of the slave station will now be described with reference to FIG Fig. 5 explains. When the system is turned on, it is at a step 120 the preparatory process is carried out. It is then determined in a step 121, whether or not the start bit was received via the loops. If it is determined that from the signals sent by means of the photoelectric converters 44 and 46 to interrupt terminals IRT1 or IRT2 of the microprocessor 60 are applied, the start bit was received, the program proceeds to a next step 122. At step 122 receive the address word and index word following the start bit. After that will be at a step 123, the received address word and the received index word are decoded and a distinction is made as to whether the present data block contains .Data which the Affiliate station or not. The distinction is made by comparing the in the read-only memory 72 stored address word with the received address word. If the present data block concerns the slave station, at a step 124 determines from the index word whether the reception operating time or the transmission operating time consists. If it is determined from the index word that the data from the main station were sent, namely the operating mode is the one for receiving the data, the program proceeds to a step 125 in which in the random access memory 74 an area for the received Data secured or determined will. In a step 126, the transmitted data is then transmitted via the input buffers 48 and 50 are stored in this area of the read / write memory 74. Thereafter a subroutine for checking the receipt of data is executed in a step 127, which is more pointedly described in detail.

If the Progrsmnl.lbl. (After step 127 is completed, proceeds the program advances to a step 128 in which, depending on the or the previously received data an access to the terminals of this extension takes place or the data recorded by these terminals are transmitted to the extension will. Thereafter, in a step 129, the address word and the index word of the The next data blocks are prepared, after which the program returns to step 121.

If it is determined from the index word in step 124 that the Main station requests data, namely the operating mode that for the data transmission is, the program proceeds to step 130 where the in the RAM 74 are transmitted to the output buffers 62 and 64. At a In the next step 131, the data from the output buffers are sent into the loops. Thereafter, the program proceeds to step 128. If at step 123 it is determined that the present data block does not relate to data for this slave station the program proceeds to step 128.

Fig. 6 is a flow chart of the aforesaid subroutine for checking the receipt of data.

The subroutine will now be described with reference to FIG. When be-i to step 113 of FIG. 3 or step 127 of FIG. 5, the subroutine is called, the program proceeds to a step 140 of FIG. at a next step 141 is the Parity of the received data checked. If the parity check shows that there is no abnormal condition, the program proceeds from the step 142 to a step 143. If a abnormal condition exists, in a step 144 the received data in the data block is erased, after which the program advances to step 143 it is determined whether the data transmitted via the clock-hand loop corresponds to the data transmitted over the counterclockwise loop match. If match exists, this is regarded as a correct transfer of the data, so that the program proceeds to step 145. The subroutine then returns to the main program return.

If there is no match between the data, that proceeds The program advances to a step 146, at which it is discriminated whether the missing Data match repeated a predetermined number of times (N times). When the data mismatch is continuously repeated N times, paces the program advances to step 147. At step 147, it is determined whether the received via either the clock-hand loop or the counter-clock-hand loop Data with you all the time. the logic level "0" or "1" were received. if the If data was received continuously, the loop on which the data was sent to the Levels "1" or "O" remain for an abnormally long period of time as a faulty loop considered, which is therefore interrupted or switched off at a step 14, cm will.

Thereafter, the program advances to step 145 and returns back to the main program. In other words, in this case, the data is about the remaining Transfer loop. If it is determined at step 146 that the data mismatch not N times occurs consecutively, or if the In step 147 it is determined that the signal "1" or t0 "is not present in any of the loops. exists for an abnormally long period of time, the program advances to the step 149, during which the received data is deleted. Then the program proceeds to step 145, thereby returning to the main program.

As shown above, in the data transmission system provided each of the slave stations with a data traversing mechanism that is based on the OR gates 52 and 54 the data sent via the loops TO the slave station transmits to the next slave station or to the master station. Hence, even then if the microprocessor of a particular substation 'or its external circuit becomes faulty, the entire transmission system is not disturbed. As a result, will when using the system as a data transmission system for motor vehicles because the system is under extremely high loads, excellent results achieved. Furthermore, in the data transmission system described, the address word and the index word of each data block transmitted from the print station decoded while the type of processing for the data area in the u data block is determined at the slave station. That is, by decoding the address word the end devices for the data block can be specified. Furthermore, through the decoding of the index word determines whether the data area of the data block serves to receive the data transmitted from the main station or data to be inserted that are to be sent to the main station. That way you can for each of the data blocks the terminals and the processing types of operation can be freely chosen. Therefore, the data blocks can be used effectively at any time and it can be compared to the case that the data blocks from the outset for the end devices for which data are sent or received, the time required for data transfer can be reduced. As a result, can in response to a change in the operational states, the control process is carried out quickly will. With the data transmission system described, with the bidirectional loop lines or ring lines are used, the data are only used if there is a match between the over the loops in the two directions transmitted data exists. In this way, any one in the data transfer can Any errors that arise can be reliably detected and the control process can be carried out safely are executed.

A loop data transmission system for a motor vehicle has at least a ring transmission line, a master station and several slave stations. Every the secondary station is equipped with at least one electrical consumer or transducer of the motor vehicle and has a logic circuit for logic adding from information received from the connected encoder to the over the transmission line received information, thereby output information for sending to the main station via this transmission line.

Claims (4)

Claims 1. Data transmission system for a 'motor vehicle with a large number of electrical consumers and transmitters, characterized by at least a ring transmission line (40, 42), one connected to the ring transmission line Main station (10) for sending information for the control of the electrical Consumers (24, 26, 32, 34) and for receiving transmitted information about the Ring transmission line and a variety of in series on the ring transmission line connected secondary stations (12, 14, 16) for receiving the transmitted information over the ring transmission line and for sending output information over the Ring transfer. transmission line, each of the substations with at least one of the electrical consumer or transmitter (20, 22, 28, 30) is connected and a logical Circuit (48 to 76) for the logical addition of the connected electrical Donors received information on the received information, thereby reducing the output information be generated. 2. System according to claim 1, characterized in that the transmitted Information (a. To g) address information (b) for designating the electrical Consumers (24, 26, 32, 34) and / or transmitters (20, 22, 28, 30) of the secondary stations (12,14,16) and that each of the secondary stations has a decoder, which decodes the received address information, in the designated electrical To determine consumers and / or donors. 3. System according to claim 1 or 2, characterized in that the transmitted information (a to g) an index information (c) for commanding the Contents of the processing in the slave stations (12,14,16) included and that each of the slave stations has a decoder which the received index information decoded to determine if the substation is taking off from the connected electrical Transmitter (20, 22, 28, 30) should send information received. 4. System according to one of claims 1 to 3, characterized in that that the ring transmission line (40, 42) is a bidirectional loop line to Transferring the information in the two opposite directions comprises, and that the main station (10) has a device for detecting an error in the data transmission system by determining whether the loop line information transmitted in both directions coincide with one another.