JPH04293637A - Multiplex communication system for vehicle - Google Patents

Abstract

PURPOSE:To provide a multiplex communication system for a vehicle capable of using a communication IC with a few bit number as compared with the number of apparatuses connected to a remote station. CONSTITUTION:A remote station 3A has a data selector 14 selecting the apparatuses transmitting to a communication IC 11 in each communication period based on the communication data transmitted from a master station. The data selector 14 further inexpensive than the communication IC 11 is used, and the cost of the remote station 3A can be reduced.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention connects a master station installed in a vehicle such as an automobile to a plurality of remote stations by a multiplex communication line, and communicates between these stations via the multiplex communication line. The present invention relates to a vehicle multiplex communication system that performs the following.

0002

[Prior Art] In recent years, multiplex communication systems have been actively developed for the purpose of reducing the number of wire harnesses that have increased as automobiles have become more sophisticated, and the applicant has also
A multiplex communication system as described in Japanese Patent No. 19448 has been proposed. This multiplex communication system is configured as shown in FIG.

A multiplex communication system 1 includes a master station (hereinafter referred to as MS) 2 and a plurality of remote stations (hereinafter referred to as RS). MS2 is a CPU
21, a direct communication code generator 22, and a bus driver 23, and is installed, for example, under the passenger seat. on the other hand,
RS consists of Front Terminal Station (hereinafter referred to as FTS) 3, Automatic Transmission Station (hereinafter referred to as ATS) 4, Combination Switch Station (hereinafter referred to as CSS) 5, Meter Indicator Station (hereinafter referred to as MIS) 6, and Graphic Monitor Station (hereinafter referred to as GMS). 7, and a rear terminal station (hereinafter referred to as RTS) 8. And these stations 3 which are RS
8 and the MS 2 are connected by a transmission line 9, which is a multiplex communication line.

[0004] A sensor switch 10 that is turned on and off in conjunction with an ignition key is connected to the MS2.

[0005] Here, the FTS 3 is installed at the front part of the automobile, and controls equipment such as a water temperature sensor, oil pressure gauge, wiper motor, washer pump, etc. at the front part of the automobile.

[0006] Furthermore, the ATS 4 is installed near the shift lever and detects the shift position.

Furthermore, the CSS 5 is installed in the dash panel section and detects the state of the connection switch.

Next, the MIS 6 is installed on the back side of the instrument panel and controls meters and indicators.

[0009] Furthermore, the GMS 7 is installed in the display section and controls the graphic monitor.

[0010] Furthermore, the RTS 8 is installed inside the trunk room, and controls equipment at the rear of the automobile, such as an exhaust temperature sensor, a back lamp, a stop lamp, a rear hazard lamp, a rear wiper motor, and a rear washer pump.

The multiplex communication system 1 as described above performs communication according to a time chart as shown in FIG. 3(a) when the ignition key is turned on.

That is, after the idle state (IDL) in which all communications are suspended, the CSS is first sent from the CPU 21 of the MS2.
The identification code ID 5 is transmitted, and the CSS 5 is activated thereby to detect the on/off state of the operation switch, and the detection result is transmitted to the MS 2.

Next, the CPU 21 of the MS2 outputs the identification code of the ATS4, thereby starting the ATS4, reading the position of the shift lever, and transmitting the reading result to the MS2.

Next, the CPU 21 of the MS2 outputs the identification code of the FTS3, thereby starting the FTS3 and receiving operation commands from the MS2, and operating the wiper motor, washable pump, etc. based on the received commands. Detection data from the water temperature sensor, oil pressure sensor, etc. is transmitted to the MS2.

[0015] Thereafter, the identification code ID is sequentially outputted from the MS2 in the order of RTS8, MIS6, and GMS7, and each time an operation command and a reading result are exchanged between the RS corresponding to the identification code ID and the MS2.

After communicating with the RS, the direct communication code DIR is output from the direct communication code generator 22 of the MS2, thereby allowing the FTS3, CSS5, MIS6, RT
When S8 is activated and CSS5 becomes a transmitting station and the on/off status of the operation switch is sequentially transmitted from CSS5, among the status data of this switch, FTS3, MIS
6. The RTS 8 appropriately receives data regarding the equipment to be controlled, and controls the equipment based on the received data. Such direct communication data includes, for example, on/off command data for headlights, horns, stop lamps, hazard lamps, side lights, turn lamps, and the like.

[0017] After that, it becomes an idle state (IDL),
After the predetermined IDL period, the MS2 and each RS
Communication between RSs and direct communication between RSs are repeated.

A time chart of communication when the ignition key is off, that is, when the vehicle is not operating, is shown in FIG. 3(b). In this case, MS2's C
Although the PU21 is stopped, the direct communication code generator 22
operates without stopping, and generates DIR at a predetermined cycle, similar to when the ignition key is turned on. Therefore, when you operate either switch,
The CSS 5 transmits the on/off state of the operation switch, and the FTS 3, CSS 5, and RTS 8 receive data regarding the equipment corresponding to the operated switch and control the equipment. In other words, by operating only the direct communication code generator 22, battery consumption when the ignition key is turned off is minimized, and control of predetermined equipment is ensured.

By the way, the time chart for communication between stations consists of a communication period and an IDL period, and as is clear from the above, the communication period consists of seven frames corresponding to each of the remote stations 3 to 8 and direct communication. Become. The data format of one frame is as shown in FIG. That is, one frame consists of three words, and one word consists of 10 bits.

The first word consists of the first 1-bit start bit (ST), 4-bit identification code (ID), and [
However, if the frame is for direct communication, the direct communication code (D
IR)], consists of a 3-bit data field for communication functions, 1-bit parity bit, and finally 1-bit stop bit (SP). The second and third words each include 1 bit ST, 7 bit data field, 1 parity bit, and 1 bit ST.
It consists of a bit SP. For example, the data fields of the first and second words are used as reception data fields to the RS, and the third word data fields are used as transmission data fields from the RS.

[0021] With the above data format, MS2
Regarding the communication data exchanged between the RS and the RS, the data in the receive data field is shifted from serial to parallel, and the data in the transmit data field is shifted from parallel to serial by a communication IC included in the RS. For example, in the case of FTS3, as is clear from FIG.
Each bit is data received by the FTS3 to control the operation of the wiper motor, washable pump, etc., and each bit in the transmission data field is data indicating the status of the water temperature sensor, oil pressure sensor, etc. transmitted from the FTS3. . The communication IC 11 shown in FIG.
It has a configuration with a 13-bit reception data output section 12 and a 7-bit transmission data input section 13, and the on/off of each sensor switch handled by the FTS3 is output to the MS2 using a 7-bit transmission data field. become.

[0022]

[Problems to be Solved by the Invention] However, in recent years, the number of warning functions etc. installed in automobiles has been gradually increasing, and accordingly, the number of sensor switches handled by the above-mentioned FTS3 has also been increasing. Therefore, the number of transmission bits of the conventionally used communication IC may not be able to output the information of all the switches to the MS2. For example, the communication IC 11 shown in FIG.
In this case, the number of switches that can output on/off status to MS2 is up to 7, and in order to support 8 or more sensor switches, a separate communication IC must be prepared, or communication with a larger number of transmission bits. It will be necessary to replace it with a new IC. However, since communication ICs require various functions such as shift registers and identification code detection sections,
There is a problem in that increasing the number or using a device with a large number of bits increases the cost of the entire system.

The present invention was made by focusing on the fact that there is information for which there is no problem even if the response from the RS to the MS is relatively slow. An object of the present invention is to provide a multiplex communication system for a vehicle that can cope with an increase in the amount of information from an RS without replacing the RS with a more expensive communication IC.

[0024]

[Means for Solving the Problem] In order to achieve the above object, a multiplex communication system for a vehicle according to the present invention provides a multiplex communication system for a vehicle that communicates between a remote station that controls a plurality of equipment and this remote station via a multiplex communication line. and a master station that communicates communication data of the plurality of equipment items, wherein the remote station shifts the plurality of communication data exchanged between the master station and the plurality of equipment items. a communication IC interposed between the communication IC and at least some predetermined plurality of equipments among the plurality of equipments; The present invention is characterized by comprising a data selector that selects an arbitrary equipment from a plurality of equipment and transmits data of the selected equipment to a communication IC.

[0025]

[Operation] In the vehicular multiplex communication system according to the invention as described above, data of a plurality of predetermined equipment connected to the data selector is transmitted to the equipment selected by the data selector during one communication cycle. Only the data of the equipment specified by the communication data received from the master station is transmitted to the master station via the communication IC. Multiple communication cycles are required to transmit all the data of the predetermined plurality of equipment connected to the data selector to the master station, but the number of bits that the communication IC transmits in one communication cycle is The number of devices may be as small as the number of devices for which data is transmitted during one communication cycle from the number of devices.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing a remote station 3A incorporated in an automobile multiplex communication system according to the present invention. This remote station 3A is the FTS in Figure 2.
MS2 and other RS4~ via transmission path 9 instead of 3
8 is connected.

The communication time chart of the multiplex communication system including this remote station 3A is similar to that shown in FIG. Further, the data format transmitted through the transmission line 9 during communication is the same as that shown in FIG. 4. However, in the communication between MS2 and remote station 3A, 3 bits of the 10-bit received data field making up the data format of FIG. Responsible for transmitting selection data. For example, the 3-bit received data field of the first word can be used as the selection data field. As is clear from Table 1 below, the 3-bit selection data can specify eight equipment items.

[0028]

[Table 1]

[0029] The remote station 3A is a communication IC 1
1 and a data selector 14.

The communication IC 11 is the conventional FTS3 described above.
The received data output section 12 has a 13-bit configuration, and the transmission data input section 13 has a 7-bit configuration. In other words, this communication IC 11 shifts in parallel the 13-bit received data that is input in series from the MS 2 via the transmission line 9 and outputs it to the equipment side, and also transmits the 7-bit data that is input in parallel from the equipment side. Data can be serially shifted and output to the transmission line 9.

The data selector 14 is connected to the communication IC 1.
Selection data SL1 to SL3 of the received data output from the received data output section 12 of No. 1 is input. These selection data SL1 to SL3 are data transmitted using the 3-bit data field of the first word in FIG. On the other hand, this data selector 14 includes a data input section 15 into which data for up to eight equipment can be input. Data indicating the status of the oil pressure sensor, exhaust temperature sensor, water temperature sensor, alternator, brake fluid level sensor, etc., and data of the turn ball breakage sensor are input to the data input section 15 of the data selector 14 in this embodiment. Ru. However, data from the turn ball outage sensor is input only when the turn signal lamp is blinking. These data input to the data input section 15 of the data selector 14 are
Equipment data is selected that does not cause any problem even if there is no response every communication cycle. For example, the data selector 14 is an oil pressure sensor when the selection data SL1 to SL3 is "000", an exhaust temperature sensor when it is "001", a water temperature sensor when it is "010", and an alternator when it is "011". , "100" selects the brake fluid level sensor, and "111" selects the turn ball break sensor. In one communication cycle, the data selector 14 transfers one data SD selected from the data input to the data input section 15 to the communication IC.
The data is output to the transmission data input section 13 of 11.

As mentioned above, the time chart of communication between stations is as shown in FIG. Communication between MS2 and remote station 3A is performed using the third data frame. therefore,
The equipment data SD input to the data input section 15 of the data selector 14 is sent to the MS2 one by one in one communication cycle according to the selection data transmitted from the CPU 21 of the MS2.
will be transmitted to. Therefore, when seven equipments are connected to the data selector 14, seven communication cycles are required to transmit the data of all the equipments to the MS2. For example, one communication cycle is 44 msec
, the data reading cycle for all equipment is 3
It becomes 08msec. However, as described above, the equipment connected to the data selector 14 is an equipment that does not cause any problem even if its responsiveness is relatively low, so an increase in the reading cycle to this extent does not pose a problem.

As described above, the remote station 3A connects to the data selector 14 a plurality of predetermined equipment such as an oil pressure sensor and an exhaust temperature sensor that do not cause problems even if their responsiveness is low, and receives the selection transmitted from the MS2. The data of one equipment is output to the MS2 every communication cycle according to the contents of the data. Therefore, to read the data of eight accessories, only 3 bits for selection data and 1 bit for transmission data are required. Therefore, when the transmission data input section 13 is 7 bits like the communication IC 11 described above, in addition to the eight equipment connected to the data selector 14, the communication IC 11
It is possible to read the data of six equipments that are directly connected to the . That is, there is no need to add a new communication IC or use an expensive communication IC with a larger number of bits in order to transmit data for eight or more equipment items. Conversely, if there is no need to read data from equipment other than the equipment connected to the data selector 14, it is possible to replace it with a cheaper communication IC with a smaller number of bits. On the other hand, the data selector 14 is much cheaper than the communication IC 11, and compared to adding a new communication IC or replacing it with a communication IC with a larger number of bits, the use of the data selector 14 The impact of cost increases is small.

Although the above embodiment has applied the invention to a remote station corresponding to the conventional FTS3, it goes without saying that it can be similarly applied to other remote stations as required.

Furthermore, the number of equipment selected by the data selector does not necessarily have to be one.

[0036]

[Effects of the Invention] As described above, according to the vehicle multiplex communication system of the present invention, by simply adding a data selector that is much cheaper than a communication IC, the number of equipment that can be connected to one remote station can be increased. It becomes possible to use a communication IC with a smaller number of bits compared to the above. therefore,
This has the effect of reducing the cost of the entire system.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a remote station of a vehicle multiplex communication system according to the invention.

FIG. 2 is a block diagram of a multiplex communication system for an automobile, which is the background of the invention.

FIG. 3 is a time chart for explaining the operation of FIG. 2;

FIG. 4 is a detailed diagram of the data format in the system of FIG. 2;

FIG. 5 is a schematic configuration diagram of a conventional remote station.

[Explanation of symbols]

3A Remote station 11 Communication IC 14 Data selector

Claims (1)

[Claims] 1. Multiplex communication for a vehicle, comprising: a remote station that controls a plurality of equipment; and a master station that exchanges communication data of the plurality of equipment with the remote station via a multiplex communication line. In the system, the remote station includes a communication IC that shifts communication data exchanged between a master station and the plurality of equipment, and a communication IC that shifts communication data between the communication IC and at least some of the plurality of equipment. Interposed between multiple equipment, communication I from the master station
a data selector that selects an arbitrary equipment from the predetermined plurality of equipment based on communication data received via the communication data selector and transmits data of the selected equipment to a communication IC. Multiplex communication system.