METHOD AND SYSTEM FOR TRANSMITTING INFORMATION AND CONTROLLING COMPONENTS

Abstract: The invention relates to a method and system for transmitting information between vehicle components (VE) in a vehicle. The vehicle components are connected to a plurality of transmission nodes (NT1, NT2...NT7), which in turn are connected to a bus (B1). The transmission nodes transmit on the bus information in the form of function parameters and parameter identifiers. The function parameters are derived by the respective transmission node from information from connected vehicle components. The information which is to be supplied to a vehicle component is derived by the transmission node to which the vehicle component is connected. The derivation takes place with the aid of functional relationships stored in the respective transmission node and function parameters received on the bus. Firstly there are sent on the bus from the respective transmission node certain function parameters having values which have changed since they were last transmitted on the bus. Certain transmission parameters having values which have not changed since they were last transmitted from the respective transmission node are only transmitted if none of the parameter values derived in the transmission node for this function parameter has been changed since they were last transmitted.

Description: METHOD AND SYSTEM FOR TRANSMITTING INFORMATION AND CONTROLLING COMPONENTS. TECHNICAL FIELD The present invention relates to transmitting information between components in a vehicle and to control the components with the aid of the transmitted information. More particularly, the invention relates to a method and a system intended at least partly to replace a conventional electrical system in a motor vehicle, preferably the electrical system in a bus or coach. BACKGROUND ART Conventional electrical systems in passenger cars, lorries, buses and similar vehicles have generally included a large number of separate conductors laid out between components in the vehicle. Somewhat simplified, it can be said that in conventional electrical systems there has been a separate electrical conductor for nearly every signal which is to be transmitted between two components. Such conventional electrical systems with a large number of separate conductors for transmitting different kinds of information have had several disadvantages, which have been well known to one skilled in the art. Consequently, a large number of different methods and systems have been proposed for several years, these systems being intended to replace conventional electrical systems in passenger cars, lorries and the like vehicles. Several proposed systems utilise a data bus for transmitting different kinds of information in time multiplex between a plurality of components in a vehicle. The European patent appliation 216372 relates to a data bus system for vehicles, in which a plurality of means are connected to a data bus via their individual transceiver stations. The transceiver stations have registers for storing data which the respective connected means needs and sends. When their respective turn comes, the transceivers send data from the connected means, in order, and sequentially on the data bus. The transceiver stations are continuously connected to the data bus for receiving data from it sent from an optional one of the transceivers and irrespective of when data is transmitted. A transceiver station sends a data telegram on the data bus after having received a selective sending order on the data bus. A data telegram includes a start code and an end code apart from data with identification characters. Data coming from different kinds of information, or coming from different transducers and the like in the vehicle, can be given different identification characters. The data telegrams from a given transceiver can have different length and contain data from different numbers of information sources. Depending on the normal rate of change for different kinds of information in the vehicle, data with different Identification characters can occur more or less often in the data telegram from a given transceiver station. In an article with the title "Proposal for an Automotive Multiplex Wiring System" and with the denotation C205/85 by E.D. van VELDHUIZEN, published through I.MECH.E. 1985, a system is described for transmitting information in vehicles. In this article there are discussed different aspects of a system, and at least "change-of-state and polling transfers" can be of interest as technical background to the present invention. DISCLOSURE OF INVENTION In the formation of methods and systems for transmitting information between vehicle components in a vehicle, these methods and systems being intended at least to partly replace conventional systems with several separate conductors between such components, there are several special problems which must be taken into consideration. One such problem is that the information which is to be transmitted from, and to, different components can be of such a different character for the different components. From many components only binary information of the type: "on/off", "open/closed", "servicable/unservicable" and the like, needs to be transmitted. On the other hand, analogously varying information needs to be transmitted from certain components, i.e. such information as "coolant temperature", "fuel quantity" and the like. At least in certain vehicles, information of the type "text row" needs to be transmitted between vehicle components, e.g. the names of bus stops for buses. Another problem in methods and systems for transmitting information between vehicle components in a vehicle is that the information which is to be transmitted from, and to different components has such a different character with respect to rate of change and variation pattern. Certain kinds of information to/from certain components vary comparatively rapidly or often, while other kinds of information vary comparatively slowly or seldom. A further problem in methods and systems for transmitting information between vehicle components in a vehicle is that certain information to, and from, certain components is particularly important from the traffic safety aspect. Legislation as to vehicle function brings with it particular requirements with regard to transmission reliability and transmission times for certain information of special interest from the traffic safety aspect. In a method in accordance with the invention, the above-mentioned and other problems have been solved primarily by deriving function parameters in transmission nodes, with the aid of information from the vehicle components, as well as primarily transmitting from a given transmission node to the other transmission nodes certain function parameters, the value of which has varied since they were last transmitted. Certain function parameters, the values of which have not varied since they were last sent from a transmission node, are sent from the transmission node to remaining nodes only if none of the parameter values derived at the transmission node for these parmeters has varied since it was last transmitted. Function parameters transmitted from the respective transmission node include parameter identitites associated with the parameter values for denoting with which function parameter the respective parameter value is associated. Functional relationships for connected vehicle components are stored in the transmission nodes, these functional relationships stating the relationship between information which shall be supplied to connected vehicle components and function parameters on the bus, as well as information from connected vehicle components. Information is derived at a transmission node and is supplied to connected vehicle components in accordance with functional relationships stored in this transmission node. Preferably, only one function parameter at a time is transmitted from the respective transmission node, so that a function parameter from at least one other transmission node is transmitted between the transmission of two successive function parameters sent from a transmission node. Certain function parameters are preferably given priority in relation to others, a parameter value for at least one priority function parameter being sent with precedence when Its value is altered in relation to the latest transmitted parameter value for the function parameter. What is distinguishing for a method in accordance with the invention and preferred embodiments thereof is apparent from the claims. In a system in accordance with the invention, the above-mentioned and other problems are solved by means functioning in agreement with a method according to the above. What is distinguishing for this system and preferred embodiments thereof is apparent from the claims. The formation of a method and system for transmitting information between vehicle components in the vehicle in accordance with the invention brings with it several advantages. One of the most important advantages with a method and system in accordance with the invention is that the transmission capacity of the data bus is utilised in an effective manner for transmitting information. By primarily transmitting certain function parameters with values which have changed, and secondarily transmitting, when there is time, certain function parameters with values which have not changed, and in that transmission takes place directly from one transmission node to the remaining transmission nodes, there is avoided to a large extent that the information transmitted on the data bus is redundant, i.e. it has already been transmitted. At the same time, there is achieved with the method and system that the data bus transmission capacity is given an automatic adjustment of its distribution regarding different kinds of information to, and from, different vehicle components. Information having for the moment a high variation rate is automatically given a larger proportion of the data bus transmission capacity- by the corresponding function parameters being sent more often. Information having for the moment a comparatively low variation rate is automatically given a minor part of the data bus transmission capacity by corresponding function parameters being sent more infrequently. By primarily transmitting certain function parameters when their values have changed there is also achieved that the mean time from when information changes to when it is transmitted will be shorter. In methods and systems using polling of the transmission nodes with the aid of a monitor node, this mean time will be particularly short in preferred embodiments, where only one function parameter at a time is sent from a transmission node. Such embodiments of the method and system in accordance with the invention are also well suited for giving priority to certain function parameters. Another important advantage with the method and system in accordance with the invention is that many of the mutually independent vehicle functions can be rapidly and simply adjusted to national rules and/or particular desires of the vehicle user or owner. The information supplied to a given vehicle component can namely be altered by altering the respective functional relationship in the transmission node to which the vehicle component is connected. Remaining functional relationships or the rest of the transmission node do not usually need to be alterd, and neither do remaining transmission nodes. Further advantages with a method and a system in accordance with the invention will be understood by one skilled in the art, after having studied the following description of preferred embodiments. BRIEF DESCRIPTION OF DRAWINGS Figure 1 illustrates a system in accordance with the invention Figure 2 illustrates a transmission node in a system in accordance with Figure 1 Figures 3-6 illustrate communication in a system in accordance with the invention Figure 7 is a flow diagram for a transmission node Figure 8 is an embodiment of a transmission node. BEST MODES FOR CARRYING OUT THE INVENTION In Figure 1 there is illustrated, heavily simplified, a first embodiment of a system in accordance with the invention. The system includes a monitor node NM, a plurality of transmission nodes NT-. - NT , a bus B-,, a bus monitoring means NS and two extra buses B 2 and B,. The monitor node and transmission nodes are directly connected to the bus B, and can communicate with each other via the bus. The bus monitoring means is connected to the bus B, via the extra buses, and can connect together the two extra buses B~ and B, should there be an interruption in the bus B, , so that an alternative signal path is created for node communication. In Figure 2 there is illustrated, heavily simplified, a transmission node NT In a system according to Figure 1. The transmission node includes an input means DR with five component inputs IN, - IN,-, and output means DT with three component outputs OUT 6 - OUTg ? a transceiver means TR, a memory means DM and a functional relationship means DF. A plurality of vehicle components VE are connected to the component inputs of the transmission nodes in the system according to Figure 1. The components VE, - VEc> connected to the transmission node in Figure 2, can be transducers for analogue or digital physical magnitudes, or they can be equipment in the vehicle sensing or discovering at least one definite occurrence or state of importance for something which is to be performd or achieved in the vehicle, when the vehicle functions in a desired manner. The vehicle components VE, - VEc can be such as transducers for coolant temperature or fuel quantity, sensing means for doors, operating means which can be actuated by the vehicle driver, etc. A plurality of vehicle componets is also connected to the component outputs of the transmission nodes in the system according to Figure 1. These components VEg - VEg connected to the transmission node in Figure 2 can be such as servo motors, setting means, indicating means or other equipment in the vehicle for carrying out some definite action, as a result of at least one definite sensed or discovered occurrence or state in the vehicle. The components VE^-VE Q can be such as electrical window openers, signal horn, braking lights, warning indicators for oil pressure or generator, ventilation fans, pneumatic door openers and door closers, headlights etc. The system according to Figure 1 can be in different states. The nodes function and communicate with each other in different ways depending on whether the system is in an initial state, a working state or a service state. Initial State When the system is connected to a power supply it automatically enters into an initial state, where the monitor node has the primary task of controlling the system and finding out what functioning transmission nodes there are in the system. The transmission nodes then have the primary task of notifying the monitor node that they are in the system, and if possible to advise whether they function or malfunction. After the monitor node has checked the system and has found out about existing and functioning nodes in the initial state, the system automatically comes into the working state, providing the check has shown, that the system functions to a sufficient extent. In Figures 3 and 4 there is illustrated an example of communication between the nodes via the bus as a result of the system in Figure 1 being power supplied. The monitor node NM first sends out a selective call with a first node address NA, of a plurality of possible node addresses NA. Further to the node address, this first selective call includes a call code MP, which denotes that the call comes from the monitor node and is a selective call. An end code ME denotes that the call comes from the monitor node and is at an end. The first selective call from the monitor node is received by all the existing functioning transmission nodes NT in the system. Each node has its own unique node address and can decide with the aid of the call code and call address in the first selective call whether it is affected by the call. Each transmission node compares the node address NA, in the first selective call from the monitor node with its own unique node address. Only the transmission node whose own node address agrees with the node adress in the first selective call from the monitor node is allowed to acknowledge the call. For the sake of simplicity, it is assumed that this transmission node is NT, , and it answers the call from the monitor node after first having received the end code MF in the call. It sends a reply call on the bus as an answer to the first selective call. This reply call includes a call code GC, a parameter identity PID, a parameter value PV and an end code NE. The call code GC denotes that it is a general call directed to all transmission nodes. The parameter identity PID states the identity of the function parameter, the value PV of which is included in the reply call. On initiation of the system, the parameter identity PID denotes that the function parameter is the operational state of the transmission node. The parameter value PV then denotes such as "in operation", "faulty" or the like. The end code NE denotes that the reply call comes from a transmission node and is at an end. The reply call from the first transmission node NT, is received by the monitor node and all transmission nodes. After having received the entire reply call, the monitor node can establish that a repy call has come in as an answer to the first selective call. The monitor node assumes that the reply call has come from the first transmission node NT-, , since it was the first transmission node which was called in the selective call. However, there is no information in the reply call itself which identifies the first transmission node, apart from the time at which the reply call was sent. The monitor node notes in a call table, however, that the first transmission node has " replied and what its operational state is, which is assumed to have been "in operation" or the like. After having received an answer to its first selective call, the monitor node sends a second selective call on the bus with the node address NA 2 to a second NT 2 of the transmission nodes. Further to the node address NA 2 , this second selective call includes a call code MP and an end ME. The call and end codes in the second and first selective call are in agreement. As with the first selective call, the second selective call from the monitor node is received by all functioning transmission nodes in the system. Each transmission node compares the node address NA 2 in the second selective call with its own node address. After having received the end code ME in the second selective call from the monitor node, the second transmission node NT 2 answers the call by sending. a reply call on the bus. The reply call from the transmission node NT 2 contains, as with the reply call from the first transmission node NT, , a call code GC, a parameter identity PID, a parameter value PV and an end code NE. The call and end codes in the reply calls from the transmission nodes NT 2 and NT, are in agreement. The reply call from the second transmission node NT 2 is received by the monitor node and all transmission nodes. After having received the entire reply call, the monitor node assumes that the reply call comes from the transmission node NT 2 and notes in the call table that the node NT 2 has replied, and what its operational state is in accordance with the parameter value PV in the reply call. The operational state is assumed to have been "operational" or the like. After having received an answer to its second selective call, the monitor node sends a third selective call on the bus with the node address NA, to a third NT, of the transmission nodes. In order to explain how the system functions, it is now assumed that there is a fault in the third transmission node NT-, so that it cannot send any reply call on the bus. The monitor node waits for the reply call for a given predetermined time after its third selective call. When the monitor node has not received any reply call within this time, it notes in the call table that no reply has come from the third transmission node. The monitor node then sends a fourth selective call with the node address NAΛ to a fourth NT of the transmission nodes, which answers by sending a reply call to the bus. After having received the reply call from the fourth transmission node, the monitor node sends a fifth selective call and so on. When the system in Figure 1 is supplied with voltage and started, the monitor node does not know the number of transmission nodes coupled into the system. On the other hand, the monitor knows which node addresses and how many transmission nodes which can be found as a maximum in the system. After having received the reply call from the seventh transmission node NT-,, the monitor node therefore sends an eight selective to an eight node address NA R . However, the system in Figure 1 has only seven transmission nodes, and there is no node with the address NA fl . The monitor node therefore does not obtain any reply call after its eight selective call, and thus notes in the call table that no eighth node has answered. The monitor node then sends a ninth selective call with a ninth node address NA g . When it has not received a reply call within the predetermined time after the ninth selective call, the monitor node notes in the call table that no ninth transmission node has answered. If the system is dimensioned so that there can be several transmission nodes with other node addresses than those so far present in some selective call, the monitor node continues to send selective calls in the described manner, with new node addresses, which have so far not been utilised, right until all possible node addresses have occurred at some time in a selective call. For the sake of simplicity it is assumed, however, that the system in Figure 1 is of a type which is dimensioned for a maximum of nine tranmission nodes. After the monitor node has selectively called all possible transmission nodes and has noted any replies coming within a predetermined time, the system automatically goes from the initial state to the operational state. In the example in Figures 3 and 4 the changeover to operational state occurs in conjunction with the selective call with the node address NA, in Figure 4. Operational State When the system is in the operational state, the transmission nodes have the task of receiving component information from connected vehicle components, transmitting between themselves on the bus information coming from connected components, and supplying the information to connected components normally required for such components to function in the intended way. In this state, the monitor node has the task, inter alia, of monitoring the transmission of information on the bus and assigning transmission time on the bus to the individual transmission nodes. Certain functions in the vehicle are more important from the safety aspect than others, and in the operational state the nodes have the task, when necessary, of providing transmission priority to a given extent to information associated with such functions. The transmission of information coming from vehicle components takes place on the bus with the information in the form of function parameters, the signals for which are transmitted on the bus from the transmission node to which the respective vehicle component is connected. For example, the vehicle components VE, - VE,- are connected to the component inputs IN, - IN,- of the transmission node illustrated in Figure 2. The input means DR in the transmission node receives on the component inputs the signals for the component information VDIN, - VDIN,- from the vehicle components, e.g. in the form of potentials of electrical voltages or amplitudes of electrical currents. The input means DR has the task of deriving function parameters FP from the component information and supplying these to the memory means and the transceiver TR. The function parameters include parameter identities PID and the parameter values PV. In the example above, with the component information in the form of potentials or amplitudes on the component inputs, the input means normally derives the parameter identities primarily with the aid of component inputs IN, - INc on which the respective potential or amplitude has been received, while the parameter values are normally derived primarily with the aid of the respective potential or amplitude. When the system is in its operational state, a transmitting node can only send one function parameter at a time and does not send several function parameters in sequence. All, or at least certain function parameters, the values of which have been changed since they were last sent, shall be transmitted first, while function parameters with values which have not been changed since they were last sent shall be transmitted when occasion permits. Among the function parameters with values that have changed, precedence is given to those which affect vehicle functions which have been given priority. The transceiver means therefore has the task of evaluating the function parameters from the input means for deciding whether they have varied compared with when they were last sent. In appropriate cases, the transceiver means TR in the transmission node forms one or two transmission queues for function parameters. In a first queue there are included the function parameters given priority, whose values have been changed since they were last transmitted on the bus. In the second transmission queue there are all the remaining function parameters which have had changed values. As long .as there is some function parameter in the first or second transmission queue, the transceiver means transmits only such function parameters on the bus. Only if there is no function parameter in either of the transmission queues does the transceiver send unchanged function parameters, and in a cyclic order in such a case. When the system is in its operational state, the transceiver means TR also has the task of receiving function parameters from the bus which have been sent on the bus from other transmission nodes. Furthermore, the transceiver has the task of transmitting to the memory means at least certain, and preferably all function parameters received from the bus, these parameters being stored in the memory means DM in memory positions determined by their parameter ϊdentitites. The vehicle components VE,,, VE-, and VE„ are respectively connected to OUTg, OUT 7 and OUT fl on the output means in the transmission node in Figure 2. The output means has the task of sending component information VDOUT^, VDOUTy and VDOUTg on the component outputs to the connected vehicle components VE ., VE 7 and VE g , e.g. in the form of electrical potentials or amplitudes of electrical currents. For the vehicle components to function in the intended manner, the component information VDOUT sent on a given component output OUT shall have a given predetermined relationship with the component information VDIN from one or more vehicle components connected to one or more components inputs IN of one or more transmission nodes. The relationship is given by a vehicle function. By vehicle function is intended here such as shall be achieved in the vehicle according to certain ' rules in the vehicle specification, as a _ result of definite occurrences or conditions in the vehicle, ' e g. the entry illumination at a passenger door in a bus shall be switched on when, and only when the passenger door is open simultaneously as the bus dipped beam is on. In the functional relationship means DF there is a functional relationship FR for each of the output means component outputs OUT, this functional relationship denoting how the component information VDOUT, which shall be sent on the component output OUT, shall be derived from at least one function parameter FP in the system and/or from the component information VDIN on at least one of the component inputs IN of the transmission node. For each of its component outputs the output means derives the component information VDOUT which is to be sent on the respective component output. The derivation takes place with the aid of the functional relationship FR in the functional relationship means DF and the function parameters FP in the memory means DM in the transmission node, and possibly with the aid of the component information VDIN directly from the input means DR in the same transmission ' node NT. The output means DT sends the derived component information VOUT to the respective vehicle component VE, usually in the form of a potential or an electric voltage or an amplitude of an electric current. In Figures 4 and 5 there is illustrated an example of the communication between the nodes when the system is in its operational state. When no parameter value has been changed in any function parameter associated with a priority vehicle function, the monitor node sends a selective call in a given cyclic order to the transmission nodes which sent reply calls in the initial state. In the example described above, the monitor node thus solely polls the transmission nodes NT, , NT 2 , NT * , NTC, NTg and NT-, in the system according to Figure 1 with the selective call in a cyclic order. The selective calls from the monitor nodes are of the same type as in the initial state. Between two successive calls the monitor node awaits for a given time a reply call of the same type as in the initial state. The one of the transmission nodes which is called by a selected call from the monitor node can transmit in its reply call a function parameter FP, i.e. a parameter value PV with associated parameter identity PID. If there are function parameters in the second transmission queue of the transmission node, the function parameter which is first in this queue is sent. If there are no function parameters in this queue the function parameters which are first in the cyclic order in the transmission node are sent. The reply calls are not selective, but directed to all nodes in the system. The parameter values transmitted on the bus are stored by the respective receiving transmission node in the memory means in memory positions corresponding to the respective parameter identity. Communication with selective calls and reply calls between the nodes continues in the manner described above as long as the system is supplied with voltage and in its operational state, and no transmission node needs to transmit any changed parameter value of some function parameter which is associated with some priority vehicle function. For reasons of space only one cycle of selective calls and reply calls after the initial state is illustrated in Figures 4 and 5. Figure 7 illustrates in the form of a simplified flow diagram an example of how a microprocessor-controlled transmission node can function, roughly speaking, in connection with derivation, transmission and reception of function parameters. In its transceiver the transmission nodule has a reception buffer RXBU for receiving information on the bus. For determining whether a call from the monitor node has been received, the transmission nodule compares the content in the reception buffer with the special codes and the node addresses which the monitor node uses. If there is simultaneously in the reception buffer a call code, an end code used by the monitor node, as well as a node address, where the codes and address together can form a call, a call is assumed to be received from the monitor node. On the other hand, if there is no call code or end code used by the monitor node in the reception buffer or if there is no node address, no call is assumed to have been received from the monitor node. In the latter case, the transmission node compares the content in the reception buffer RXBU with the codes and the function parameters used by the transmission nodes. If there is simultanously in the reception buffer RXBU a call code GC, an end code NE which are used by the transmission nodes NT and furthermore a function parameter with identity PID and value PV, where these codes and function parameter together can be a reply call, a reply call is assumed to have been received from some unidentified transmission node. If, on the other hand, there is no call code GC or end code NE in the reception buffer or there is no function parameter, no reply call is assumed to have been received from any transmission node. If a reply call from some transmission node is not regarded as having been received, the transmission node performs one or more of a plurality of operational tasks, which shall be performed in a cyclic order for certain such tasks. After having performed one or more of the tasks in the cyclic order, the transmission node once again compares the content in the reception buffer with the special codes and the node addresses used by the monitor node. If the content in the reception buffer is such that a call is regarded as having been received from the monitor node, the transmission node resets a monitoring means which indicates a fault in the communication when it is not reset within a given time. After resetting the monitoring means, the transmission node compares the node address in the received call in the reception buffer with its own address. If the node address in the qail does not agree with its own address the transmission node performs one or more of the operational tasks which are in readiness to be performed in accordance with the cyclic order. The node then compares once again the content in the reception buffer in the way described above. If the node address in the call in the reception buffer agrees with the address of the transmission node, the latter is regarded as having been called and shall send a reply call. The transmission node then investigates whether there is some function parameter having a value which has changed since it was sent. If there is a single such function parameter it is sent in the reply call from the transmission node. If there are two or more such function parameters in a transmission queue, the one first in the queue is sent. If the value of no function parameter has been changed since it was last sent, the transmission node sends in the reply call the function parameter which is next in turn according to the cyclic order. After transmitting the reply call, the transmission node once again performs one or more of the operation tasks included in the cyclic order. The node then compares once again the content in the reception buffer and determines whether a call or a reply call had possibly been received in the manner described above. If a reply call is regarded as having been received from some transmission node, the transmission node collects the parameter value PV and identity PID from the reply call in the reception buffer. The transmission node stores the parameter value in a memory means at a memory position having an address determined by the parameter identity. With the aid of the latter, there is obtained from the functional relationship means DF the possible functional relationship(s) FR in which are included the value of the parameter with the identity PID in the reply call. The transmission node then derives the component information VDOUT in accordance with each such possible functional relationship. After which the node once again performs one or more of the operational tasks included in the cyclic order for operational tasks, and finally compares once again the content in the reception buffer in the way described above, and determines in the way described above whether a call or reply call have possibly been received. Changed values of function parameters associated with some priority vehicle function shall be transmitted with priority. Where the input means of a transmission node derives a function parameter associated with a priority vehicle function and where the value of such a function parameter is changed, the transmission node shall notify the monitor node that such a changed value needs to be transmitted. In Figure 6 there is illustrated an example of the communication between the nodes in conjunction with a change in the value of a priority function parameter occurrring in the transmission node NT— For the sake of simplicity, it is assumed that for the example illustrated in Figure 6 priority function parameters are only derived in the transmission nodes NT, and NT,-. The transmission node NT,- notifies the monitor node that there is a need in the system to transmit a changed value for a priority function parameter by sending on the bus an interruption call XXX, approximately simultaneously as the monitor node transmits a selective call with the code address NA-,. The monitor node interrupts its transmission of selective calls in the definite cyclic order when the monitor node discovers that the transmission is disturbed by an interruption signal. The monitor node then goes over to sending in order of precedence priority calls solely to the transmission node deriving priority function parameters. It is not apparent from the interruption call which transmission node which has a need of transmitting a priority function parameter. The monitor node therefore first transmits a first priority call with the node address NA, to the first of the transmission nodes deriving priority function parameters. Apart from the node address NA,, the first priority call includes a call code PP and an end code ME. The end code agrees with the end code in ordinary selective calls from the monitor node, but the call code PP differs from the call code in ordinary selective calls from the monitor node. This code PP denotes that the call is a priority call and that the call comes from the monitor node. The monitor node thereafter awaits a reply during a predetermined time after the first priority call. The first transmission node NT, answers the first priority call with a reply call. The reply call includes a call code GC, a function parameter identity PID, a parameter value PV and an end code NE. The call code GC and end code NE agree with corresponding codes in the call code for ordinary selected calls. The parameter identity PID and value PV relate to a priority function parameter which is derived from the transmission node NT, . If no priority function parameter is to be found in the first transmission queue in the transmission node NT the one of the priority function parameters of the transmission node which is in front of other possible priority function parameters in the cyclic order of the transmission node NT, is transmitted. If there is only one priority function parameter in the first transmission queue of the node NT, , this parameter is sent in the reply call on the first priority call. If there are two or more priority function parameters in the first transmission queue of the node NT, , the parameter which is first in the first queue is sent. After having received the reply call from the first transmission node NT, within a given time after the first priority call, the monitor node NM transmits a second priority call. This call contains the node address NA 5 to the next one of the transmission nodes deriving priority vehicle functions. The monitor node then awaits a reply during a predetermined time after the second priority call. The fifth transmission node NTc answers the second priority call with a reply call. The reply call is of the same type as the reply call from the transmission node NT, . In this reply call the node NTc transmits the function parameter, of which the value has been changed, and which has caused the transmission node to transmit the interruption signal XXX. After having received the repy call from the fifth transmission node NTc within a given time after the second priority call, the monitor node once again returns to transmitting and awaiting calls according to the normal call cycle including all existing, functioning transmission nodes NT, , NT 2 , NTΛ, NTC, NT, and NT-,. The monitor node then once again returns to the place in the normal call cycle where it was before the interruption signal came, and transmits a selective call with the node address NA-,. The monitor node thus only transmits a single priority call to each of the transmission nodes deriving priority vehicle functions, when the monitor node discovers an interruption call. If a transmission node needs to transmit two priority function parameters having values which have been changed since they were last transmitted., it must therefore transmit an interruption call twice. The reply call after a priority call is of the same type as the reply call after normal selective calls and has the same call code GC. Each transmission node therefore deals with received reply calls after priority calls, i.e. transmitted parameter values PV are stored at memory positions determined by the transmitted parameter identity PID. Servicing State With the aid of an extraneous unit connected to the system, this unit being hereinafter being called the service node, the system can be put into a servicing state. The latter is primarily intended for testing and fault finding in the system in conjunction with maintainance, repair and alterations in the system. The servicing state can, however, be used in other connections when the vehicle is not needed to be driven in general traffic in a traffic-safe manner e.g. when demonstrating the system in a stationary vehicle. In this state, the monitor node transmits no selective or priority calls on the bus. Such calls can be transmitted by the service node instead, and the service node is not bound to the cyclic order for selective calls and priority calls applicable in the operational state. The service node can transmit calls in an optional order determined by a test programme, demonstration programme or manually. Apart from selective calls and priority calls of the same type as the monitor node transmits in the operational state, the service node can also transmit simulated reply calls and service calls. The simulated reply calls are of the same type as the reply calls from the transmission nodes in the operational state. The service calls include a special call code SP, a node address NA and an end code ME The node address and end code in a service call are of the same type as the corresponding ones in a call from the monitor node in the operational state. On the other hand, the call code SP In a service call differs from the call code MP in a selective call and the call code PP in a priority call. In the servicing state the transmission nodes react to selective calls and priority calls from the service node in the same way as they react to corresponding calls from the monitor node in the operational state. In the servicing state the transmission nodes also react to simulated reply calls from service nodes in the same way as they react to reply calls from a transmission node in the operational state. By sending calls from the service node and analysing how the transmission nodes react to these calls with reply calls and component information to the vehicle components, the transmission nodes can be tested and faults in the system localised. Only the transmission node whose address agrees with the node address in the service call reacts to the service call. As an answer to the service call this transmission node transmits a status reply on the bus. The status reply includes a special call code ISC, data and an end code NE. The end code in a status reply is of the same type as the end code in a reply call from a transmission node in the operational state. On the other hand, the call code SC in a status reply differs from remaining call codes occurring in the operational and servicing state. Data in a status reply can vary from node to node in accordance with instructions stored in the respective node. For example, data in a status reply can include all function parameters derived by the transmission node, and all component information received by the transmission node on its component inputs, and which it transmits on its component outputs connected to vehicle components. The nodes In Figure 8 there is illustrated, strongly simplified, an embodiment of a transmission node intended for a method and a system in accordance with the invention. The transmission node includes a processor 1 of the type HC 6303 with timer 2, SCI-communication section 3 and input/output means 4. The communication section of the processor is connected via a communication drive stage 5 according to specification RS 485 to the system bus B. The processor also has connected to it an EPROM memory 6 of the type 27128 with the capacity 16kB and a RAM memory 7 of the type 6264 with the capacity 8 kB. Functional relationships FR and a program for the processor are stored in the memory 6. The parameter values are stored in the memory 7. A so-called watchdog 8 for the processor monitoring is connected to a reset input of the processor 1. The input/output means 4 of the processor are connected by a serial internal bus 9 to four integrated circuits 10, 11, 12 and 13. The integrated circuit 10 is of the type Pcf 8591 from Philips, and has four inputs IN for analogue component information from vehicle components and an output OUT for analogue component information to a vehicle component. For reasons of space, only one of the analogue inputs IN and the analogue output OUT are illustrated. The integrated circuit 11 is of the type Pcf 8574 from Philips, and has eight inputs IN for digital component information from vehicle components. For reasons of space, only two of the digital inputs IN are connected to their respective vehicle component in the form of a switch 15 and a switch 16. The integrated circuits 12 and 13 are also of the type Pcf 8574 from Philips. The integrated circuit 12 has eight outputs OUT, each connected via its output stage 14 to its Input OUT for digital component information. For reasons of space, only one of the output stages 14 is illustrated, all of which are of the type SMT 12 from Siemens. The integrated circuit 13 has eight inputs IN connected to a status output SU on each of the output stages 14. By supplementing the transmission node according to Figure 8 with further integrated circuits of the type Pcf 8591 and/or type Pcf 8574 and associated output stages of the type SMT 12, the transmission node can be modified so that it is given more analogue and/or digital inputs and/or outputs for component information. A monitor node intended for a method and a system in accordance with the invention can include a processor with associated means corresponding to 1-8 in Figure 8, connected to each other in a corresponding way as with a transmission node. The EPROM memory 6 in such a monitor node then includes a partially different programme from the EPROM memory in the transmission node, since the monitor node is to function in a partially different manner from a transmission node. The RAM memory 7 in such a monitor node thus includes, inter alia, information as to which transmission node which has answered the monitor node call and is operational. A monitor node which is not directly connected to some vehicle component naturally does not need to include any means corresponding to 10-14 in Figure 8. A service node intended for a method and a system in accordance with the invention can at least partially be implemented in a similar way as a transmission node according to Figure 8 and the above-described monitor node. The RAM memory 7 in such a service node can then contain the parameter values as well as data which the service node receives in status replies from transmission nodes. The RAM memory 7 can also contain criterion values or the like, with which the parameter values or data in the status reply from the transmission nodes shall be compared with in testing or fault finding. Testing and fault finding programs can be stored in the EPROM memory 6 and/or the RAM memory 7. The capacity of these memories can thus be different in the service node from what they are in the transmission nodes. Instead of the integrated circuits 10-13 in a transmission node according to Figure 8, a service node can have a keyboard, a printer, video screen or other presentation means connected to the processor via an internal bus. There are several conceivable alternatives for achieving that a system in accordance with the invention comes into the servicing state. One of the most simple is that the current supply to the monitor node is interrupted and that the service node is connected to the bus B via a contact means on the vehicle. A more sophisticated alternative is that the service node has its own node address similar to the node address of the transmission nodes. In this alternative, when the system is provided with voltage and comes into the initial state, the monitor node sends a selective call with the service node address before the selective calls with the addresses of the transmission nodes, and if it then receives a reply call it ceases to transmit selective calls and goes over to an inactive state as long as it is supplied with voltage. The system described above is dependent on a functioning monitor node. When increasing safety and reliability in such a system it is conceivable to implement it so that there is a reserve monitor node, which is inactive as long as the ordinary monitor node functions in the intended manner, but when the ordinary monitor node malfunctions takes over its task in the operational state and possible also in the initial state. The reserve monitor node can be a separate monitor node of similar implementation as the normal one, but with a somewhat different programme in its EPROM memory 6. Alternatively, it is conceivable to allow one of the transmission nodes to function as reserve monitor node. This transmission node will then differ from the other transmission nodes primarily by the programmes in its EPROM memory and the information in its RAM memory, and these memories may possibly need greater capacity than the corresponding memories in an ordinary transmission node. The invention is not restricted to the above described embodiments of the method and system, and within the scope of the claims a method and system in accordance with the invention can deviate from the described embodiments.

Claims: CLAIMS 1 A method of transmitting with the aid of a plurality of transmission nodes (NT, , NT 2 , ... NT- connected to a bus (B,) in a vehicle, information between vehicle components (VE) in the vehicle such that vehicle functions are achieved in the vehicle, in which method component information (VDIN) from the vehicle components being received in the transmission nodes, function parameters (FP) having values (PV) and identitites (PID) are derived in the nodes with the aid of the component information (VDIN) from the components (VE), said parameter identitites (PID) indicating to what function the parameter (FP) and respective parameter value (PV) are associated, function parameters (FP) with parameter values and parameter identitites (PID) are sent from a respective transmission node on the bus (B,) to remaining transmission nodes, function parameters (FP) with parameter values (PV) and parameter values (PID) sent on the bus from remaining transmission nodes being received by the respective transmission node, at least certain of the parameter values (PV) received on the bus being stored in the respective transmission node, characterized in that from the respective transmission node there are firstly sent certain function parameters (FP) having values which have been changed since they were last transmitted on the bus from the transmission node, in that certain function parameters (FP) having values (PV) which have not been changed since they were last transmitted from a transmission node are transmitted from the respective transmission node only if none of the values for these function parameters derived at the transmission nodes have been changed since they were last transmitted, in that function relationships (FR) are stored in the transmission nodes for the vehicle functions which are to be achieved, these function relationships (FR) denoting the relationship between the component information (VDOUT) which is to be supplied to the vehicle components (VE) and function parameters (FP) transmitted on the bus and component information (VDIN) from vehicle components (VE), and in that component information (VDOUT) is derived at the respective transmission node and supplied to vehicle components in accordance with the functional relationship stored in this transmission node. 2 Method as claimed in claim 1, characterized in that in the respective transmission node the latest derived parameter value (PV) for the respective function parameter (FP) is compared with the latest transmitted parameter value (PV) for the respective function parameter before transmitting certain derived function parameters. 3 Method as claimed in claim 1, characterized in that the respective transmission node, and in conjunction with deriving certain function parameters, the pertinent component information from the respective vehicle component (VE) is compared with previously received component information from the same vehicle component (VE). 4 Method as claimed in claims 1, 2 or 3, characterized in that only one function parameter (FP) at a time is sent on the bus (B,) from the respective transmission node, and in that between transmission on the bus of two successive function parameters (FP) from the same transmission node, a function parameter (FP) from at least one other transmission node is transmitted on the bus. 5 Method as claimed in any one of the preceding claims, characterized in that certain function parameters are. given priority in relation to others when transmitting on the bus, such that when a priority function parameter value is changed in relation to its latest transmitted value a parameter value for at least one priority function parameter is transmitted with priority on the bus. 6 Method as claimed in any one of the preceding claims characterized in that function parameters (FP) and component information (VDOUT) to connected vehicle components (VE) are derived in at least certain of the transmission nodes according to a cyclic order, which can differ from node to node depending on what vehicle components are connected to it, in that on receiving a function parameter (FP) from the bus the cyclic order for derivation of function parameters and component information is interrupted, in that component information (VDOUT) is derived in accordance with possible function relationships (FR) determined by the received parameter identifier (PID) of the function parameter, and in that the derivation of function parameters and component information subsequently continues according to the cyclic order. 7 A system for transmitting information between vehicle components in a vehicle and with the aid of transmitted information and vehicle components achieving vehicle functions in the vehicle, said system including a plurality of transmission nodes (NT, , NT , NT,, NTΛ, NTC, N τ g> NT-,) connected to a bus (B,) in the vehicle for transmitting signals between the transmission nodes, said nodes each having at least one component input (IN) for receiving from a vehicle component (VE) component information (VDIN) of importance for a vehicle function which is to be achieved, said transmission nodes each having at least one component output (OUT) for emitting component information (VDOUT) to a vehicle component (VE) for achieving a vehicle function, said transmission nodes including means (TR) for transmitting signals (GC + PID + PV + NE) on the bus (B,), these signals including function parameters (FP) derived (VDIN) from component information from their connected vehicle components (VE), said transmitted function parameters including parameter identities (PID) in conjunction with the parameter values (PV), said parameter identities (PID) indicating to what function parameter (FP) the respective parameter value (PV) is associated, said transmission nodes each including means (TR) for receiving signals (GC + PID + PV + NE) with function parameters (FP) transmitted on the bus from an optional one of a plurality of transmission nodes (NT, - NT-,), and irrespective of when the signals are sent on the bus from the respective transmission node, said nodes each including memory means (DM) for storing, in appropriate cases, at least certain function parameters (FP) received in signals (GC + PID + PV + NE) on the bus, said transmission nodes each including output means (DT) for deriving, with the aid of at least one function parameter (FP) received via the bus, and emitting component information (VDOUT) on its own component output (OUT), characterized in that each of the transmission nodes includes means for firstly sending certain function parameters having values (PV) which are changed in relation to when they were last transmitted, in that each of the transmission nodes includes means for solely secondly, and as time permits, transmitting certain function parameters having values (PV) which have not been changed in relation to when they were last transmitted, and in that each of the transmission nodes includes means (DF) for storing functional relationships (FR), which disclose the relationship between the component information (VDOUT), which shall be given to the vehicle components (VE) on the component outputs (OUT), and function parameters as well as component Information (VDIN) transmitted on the bus from vehicle components (VE). 8 A system as claimed in claim 6, characterized in that certain function parameters (FP) are given priority in relation to remaining function parameters, in that certain of the transmission nodes (NT, , NTc) are adapted to give priority to parameter values (PV) for priority function parameters when transmitting on the bus, and in that each of the transmission nodes is adapted to disturb (XXX), in appropriate cases, the transmission on the bus from another transmission node in order to transmit a parameter value (PV) for a priority function parameter (FP). 9 A system as claimed in claim 6, characterized by a monitor node (NM) with means for calling the transmission nodes according to predetermined rules with selective calls (MP + NA + ME) on the bus in a given order and to allow the transmission nodes the possibility of transmitting in order and in turn reply calls (GC + PID + PV + NE) with a function parameter (PIC + PV), in that certain function parameters are given priority in relation to remaining function parameters, in that certain of the transmission nodes include means (TR) for disturbing (XXX) the transmission of calls (MP + NA + ME) of the monitor node (NM) on the bus for, in appropriate cases and where necessary, notifying the monitor node that a parameter value for a priority function parameter (FP) has been changed since it was last transmitted, in that the monitor node, on noting the need of transmitting a parameter value for a priority function parameter, temporarily interrupts its selective calls in the given order, in that the monitor node subsequently transmits according to predetermined rules priority calls (PP + N A + ME) with node addresses (NA) in order and in turn solely to the transmission nodes (NT,, NTc) deriving and transmitting priority function parameters.

Inventors: ANDERSSON TOR FRITZ INGVAR, HOEGBERG BO ARNE GUNNAR, ANDERSSON, TOR, FRITZ, INGVAR, HOEGBERG, BO, ARNE, GUNNAR
Applicants: ERICSSON TELEFON AB L M, TELEFONAKTIEBOLAGET L M ERICSSON
Application year: 1988
Main classification: G08C19
IPC codes: B60R16, G08C15, H04L29, H04Q9