|Title of Invention||
METHOD FOR CHECKING A MONITORING FUNCTION ON A BUS SYSTEM
|Abstract||The invention relates to a method and device for testing a monitoring function of a bus system, in addition to a bus system comprising at least one user. First time slots are provided, during which messages are transmitted and a communication cycle is formed from a number of first time slots in such a way that messages are transmitted during first time slots. According to the invention, the number of first time slots and the respective position of a first time slot for the messages of the user are predefined. A second time slot is provided after the communication cycle and no messages may be transmitted during said slot. The monitoring function is tested in said second time slot.|
Process and Device for verification of a Monitoring Function of a Bus System and the Bus System
Current Status of the Technology
The Invention relates to a process and a Device for verification of monitoring function of a Bus System, and the Bus System itself in accordance with the generic term of the Independent Claims,
The interlinking or networking of Control Devices, Sensor Systems and Recording Systems with the help of a Communication System of a Bus System has vastly increased in the last few years in the design of modem automobiles or in the machine-building industry, particularly in the area of machine tool fabrication as well as in the automating sector. Through the distribution of functions among several control instruments, synergy effects could be achieved. In this context, one would speak of a distributed system. Communication between different Stations takes place more and more through a Bus and/or a Bus System. The Communication Traffic on the Bus System, Access and Receive mechanisms as well as error handling are regulated through a Protocol. CAN (Controller Area Network) has established itself as the Protocol in the automobile sector. This is an event-driven protocol, that means, protocol activities, such as the transmitting of a message, are triggered or initiated through the events, which have their origin outside of the Communication System. The clear access to the Communication System and/or Bus System is triggered through a priority-based Bit Arbitration. The prerequisite for this is that each message is allotted with an unambiguous priority. The CAN-Protocol is very flexible. Insertion of further nodes and messages is thus effortlessly possible, as long as free priorities are still available.
An alternative extension or stage of such an event-driven spontaneous communication is the pure time-driven alternative. All communication activities on the Bus are strictly periodical. Protocol activities, such as transmitting of a message are triggered purely through the progression of a time valid for the entire Bus System. The access to the Medium is based on the allocation of time ranges and/or time slots in which a transmitter has exclusive transmission rights. Insertion of new nodes would then be possible, ff the corresponding time slots were made free in advance. This circumstance or state-of-affairs necessitates that the message sequence is already frozen before the commissioning, whereby a schedule is prepared, which must adequately meet the requirements of the messages with reference to Repetition rate, Redundance, Deadlines, etc.
Besides the event-driven application and the purely time-driven application, also a time-driven CAN-Alternative, the so-called TTCAN (time triggered controller area network) is known. This' meets the requirements sketched above for time-driven Communication as well as the requirements for a certain amount of
flexibility. The TTCAN fulfills these through the structuring of the
Communication Round (basic cycle) in the so-called exclusive Time window and /or Time slot for periodic messages of specified participant in the Communication and in the so-called Arbitrating Time window or Time slot for spontaneous messages of several participants in the Communication.
Besides the Bus System mentioned above, a multiplicity of Bus Systems and/or Communication Systems for interlinking of participants in distributed systems are known.
For Communication systems and/or Bus systems, a series of possibilities are available to prevent or to solve access conflicts. In CAN, for instance, the Bitwise arbitration is adopted. This is very robust, but because of the Run-time phenomenon, the maximum transmission speed is limited by the very principle. Under the Time-driven Communication system, the access problems are solved through Attempt and Configuration. The conflicts are already prevented off-line through advance planning, The prerequisite however is a common understanding of the time, which has validity throughout the network. In these Systems, however, generally there is no possibility to process, in error cases, the access conflicts, because the access in itself could not be prevented. Therefore, it is customary to introduce the so-called Bus Guardian or Bus Monitor BG as an additional unit, which allows the physical access only in the configurated time slots. Thus, even in error cases, the access conflicts can be solved or prevented.
As in the case of all monitoring systems, here also the problem of inherent monitoring capability of the Monitoring system presents itself. The important function of the Bus Guardian or Bus Monitor, mainly the physical prevention of the access, is never required in normal cases, and to this extent therefore the availability of this function is also not tested. From the point of view of the System, a monitoring of this function is however necessary, in order that one is not required to deal with dormant errors. In this respect, the DE 199 50 433 A 1 is known to be the state-of-the-art of technology. A procedure for monitoring this function is described therein. What is disadvantageous in the above referred to state-of-the-art of technology is however, that the Monitoring and/or verification of the Bus Guardian function happens in a time slot, which is almost always customarily used for message transmission and which, under the framework of verification cannot be used for the purpose. That means, within a regular Communication time, time which normally was visualized for transmitting the messages is consumed to the advantage of the Bus Guardian-Test,
Thus, it is evident that the state-of-the-art of technology referred to is not in a position to deliver optimum results in all circumstances. Thus emerges the task to optimize the above mentioned situation and to circumvent the disadvantages arising from the state-of-the-art of technology.
Advantages of the Invention
The Invention is based on a process and a device for verification of a Monitoring function of a Bus System as well as a corresponding Bus system with at least one participant; in which: a first set of time slots are visualized, on which messages are carried, and a Communication cycle consisting of a number of first Time slots is created in such The significant advantage of the above mentioned Invention lies therein, that no time within the Communication cycle which is meant normally for the purpose of transmitting messages, is required to be consumed in favour of the Bus Guardian test. The suggested Test Time Point is therefore within a second Time slot, which is not used for Active Communication, the so-called Network Idle Time NIT.
The Monitoring function is purposefully so designed, that the messages of the participant, which are sent outside of the Initial time slots visualized for such messages, are blocked.
What is additionally purposeful is that in the second Time slotT the internal Protocol tasks of the participant are processesed, which must be processed in any case under the framework of a cyclical house-keeping exercise. For this purpose, for instance, the determination of a time correction value is worthwhile and purposeful, in order that the local time of a participant can be adjusted or matched to a global time of an entire Bus system.
The Monitoring function is verified in such a fashion, that the participant attempts to send a test message in the second Time slot and verifies whether such a test message was blocked. What is so advantageous is that the participant himself can read again the message sent by him from the Bus system and can thus carry
out by himself the verification whether the test message was blocked or not, ie a Loop-Back-Function is available for the purpose.
In yet another advantageous design, the test message has a Signal Form, which is unambiguous in the Bus system in order to differentiate the transient beams for instance, as part of the EMV-Problem (Electromagnetic Compatibility).
Appropriately, each participant carries out the verification of the Monitoring function by himself, whereby simultaneously, only one single participant can carry out the verification of the Monitoring function.
In yet another advantageous design, the participant is allotted with a concrete Time slot specifically for the purpose of verification. This can be one-third of the Time slot within a second Time slot, or a concrete Time slot after a concrete Communication cycle, so that it is unambiguously clear which participant in which time slot may carry out the verification.
Additionally, what is advantageous is that each participant is allotted with a test message of his own, whereby the test messages of the individual participants are different from each other.
In this context, it is advantageous that test message allotted to one of the participants can be received only by that one to whom the allotment has been made.
If each of the participants is allotted with a clear test message or a Time slot, then even at least the second participant can carry out the verification of the Monitoring function of the first participant and forward the result of this verification to the first participant.
In a very special design, the Bus system is developed on a Star Topologyt whereby each participant has a connection to one of the Coupling elements of the Bus Star, and the Coupling element is so designed that a Test message of a participant is not forwarded through the Coupling element to other participants, with the result that each participant can carry out a self-verification.
Further benefits and advantageous designs would arise from the description as well as characteristics of the claims.
The Invention is further elucidated in the following on the basis of the figures illustrated in the drawing.
The drawing shows:
Figure 1 The Bus system with at least one participant, especially two participants
for illustration of the Invention-based process.
Figure 2 shows under the framework of a Signal illustration, the invention-based monitoring of the Bus Guardian-Function,
Figure 3 illustrates the Bus system in special design in Star Topology with Coupling elements.
Description of the Design Examples.
Figure 1 shows a Communication Network or Communication system and/or Bus System 109 with a Bus 100. Participants 101 and 102 are connected or coupled to this Bus, which respectively include a Coupling element, specially a Bus Controller 104 or 103. A processing unit 105 or 106 is symbolically illustrated in the Bus Coupling unit 103 or 104, as well as a relevant Bus Monitor or Bus Guardian or the corresponding function with Block 107 or Block 108. The arrangement of the processing unit, Bus Controller or Bus interface and Monitoring function is to be seen in this context as an example. Similarly, the processing as well as the Monitoring function can be carried out in the participant directly. For this purpose, any optional allocation of processing function and Monitoring function to the Bus Controller or participant himself is possible. Even an external arrangement of the components and functions mentioned in relation to the participant is feasible.
Figure 2 shows the Communication on the Bus with a first Communication cycle C1, a Communication cycle C2 and a Communication cycle C3. In this context, the Communication cycles are divided in several time slots, in this case for instance, illustrated.through the Time segment or Time Slots S1f S2, S3 and /or Sn. Subsequent to each Communication cycle C (C1f C2..) the so-called Network Idle Time NIT follows, here NIT1 for C1 and NIT2 for C2. This Network Idle Time is a time range, which can be attributed to the actual Communication Round, in which however no messages may be transmitted. In the Network Idle Time, in accordance with definition, important internal Protocol tasks, such as for instance, the calculation of the Clock correction values for matching a local time of an individual participant to the global Time of the network Bus system are
carried out. In an error-free event in the Network Idle Time, not a single Controller or Bus Controller BC transmits and the Bus Guardian BG must protect this area for all Controllers. For this purpose, a separate Time Series for the Bus Guardian as well as for the corresponding, optional Bus Controller BCX is illustrated. The prerequisite for conclusive end-to-end test is that a transmission attempt is made and its prevention through the Bus Guardian is verified.
The prerequisite for the process is that the transmission course of the Communication System is cyclically developed as mentioned above, and is structured in the so-called Communication cycles or Communication Round. What would be advantageous-is that each node or participant or Bus Controller has the possibility to detect whether the test has had negative results; that means, the participant reads back by means of a Loop-Back, the actual signals. In the sections BGC1 and/or BGC2 the Bus Guardian blocks the transmission possibility through the Bus Controller BCX. This BCX has the possibility to transmit to the bus, within the lime slots visualized for it, in this case S3 and Sn, normal message, in this case BGN1 and/or BGN2 to the Bus. In these Time slots, the transmission of the message through the Bus Controller BCX via the Bus Guardian BG is permitted, as illustrated through BG01 and BG02.
In accordance with the Invention, a Bus Guardian-Test is not carried out in the time available for the purpose of Communication, but in a time in which no Communication on the Bus is permitted or planned, i.e., in the so-called Network Idle Time . For this purpose, a Controller, here BCX, can send during the Network Idle Time a Signal, particularly a Test signal, in this case illustrated with TS1 and/or TS2, whereby verification would then be made whether the transmitted signal or the transmitted message is visible on the Bus or not. If the message is visible on the Bus, then the Blocking exercise had failed. If in the slots BGTS1 and MGTS2 the corresponding test signal on the Bus can be detected, then the Blocking through the Bus Guardian has not. been carried out and the Monitoring function is defective.
The Signals TS1 and TS2 as Test signals or Test messages are transmitted from the Bus Controller BCX, illustrated with BGT1 and VGT2. If the corresponding Bus Controller and/or the corresponding Processing Unit in the Network Idle Time sends a Signal and it notices nothing on the Bus, then this Signal has not passed through the Bus Guardian-Block and the functional capability of the Bus Guardian BG with reference to the blocking is successfully proven. In Negation moreover, also the functional capability with regard to the Transmission slot being open, BG01 and/or BGG2 can be verified. If the Test or the verification of the Monitoring function of the; Bus Guardian returns a Signal, there are several possibilities to determine whether a Node has the error in itself or not. To start with, one can generally differentiate between errors and transient beams by prescribing specific Signal forms and repetition of the Test That means, that the
Test message and./or the Test Signal clearly is allotted with a Signal form, so that these can be recognized and differentiated from the other Signals. For confirmation the test can be repeated similarly in order to differentiate a one time beam or a one-time Error signal from a systemic defect.
Further more, one can prescribe two Nodes or two participants or Bus Controller or processing units to undertake the verification of the Bus Guardian-Function simultaneously. For once this can happen, by each participant or Bus Controller being allotted with a concrete Time slot in the Network Idle Time, for instance, BGTS1 and/or BGTS2. On the other, a complete Network Idle Time, such as NIT1 or NIT2, can be allotted to a specific Bus Controller, so that for example, in NIT1 the Bus Controller 103 and in NIT2 the Bus Controller 102 can carry out the test of the Bus Guardian-Function in accordance with the corresponding Communication cycle.
If such an allocation of specific; Time slots or even clear Signal forms of the Test messages from corresponding participants to the respective participant is not carried out and if all nodes could make the test simultaneously, as a result of which, the Signals from one Node could spread to all other Nodes, then a Node cannot but interpret different Signals measured from 0 as errors or the error evaluation is not conclusive.
In order to prevent this, it is for instance possible, to allot concretely the testing exercise of a Communication round with the relevant Network Idle Time NIT, or to reserve also Time slots in the NIT concretely for Test runs, so that under given circumstances, also several test runs can be enabled in one NIT.
Whenever therefore, it is ensured through configuration or through advance measures that two test exercises or verifications of the Monitoring function of different nodes cannot overlap among themselves, a Test signal can be interpreted as error indication for the currently testing note.
On the other hand, if tests time-wise overlap among themselves, one can plan for the possibility that a clear error identification is made possible, through different Test signals, which can be allotted to any tester or node or such similar device. That means, the Signal form of the Test Signal or the Test message can be different from participant to participant, Bus Guardian to Bus Guardian. Then, it is also possible that the Bus Guardian-Monitoring is not carried out by each participant himself, but by other participants for a different participant; for instance, by Participant 101 for Participant 102. The same is applicable if a specific Time slot or Time segment, as described above, is allotted to the Test, so that the other Nodes can judge the success of the Test or can notify a Test result of the tested participant, for instance, through a suitable acknowledgement under the framework of the Protocol mechanism or an explicit message.
A special design illustrates a Bus System in Star Topology, as in Figure 3. In this context, again Bus participant 302, 303 and 304 are illustrated, which respectively include a Bus Controller 308, 309 and/or 310. As in Figure 1, a processing unit 311, 312 and/or 313 is illustrated again, as well as the Bus Guardian-Function or the monitoring of the Bus Guardian-Function 314, 315 or 316. For the participant or the corresponding Bus Controller, similar prerequisites or assumptions or possibilities, as indicated in Figure 1 would apply. These participants are coupled now respectively to a Bus 305, 306 or 307. The participant or the corresponding Buses are linked through a Coupling element 301. In this Star Topology illustrated, one can now use the physical characteristics of the Star and choose the Test Signals or the Testmessages in such a manner that they do not multiply themselves outside of the Star. That means, the Test of the n . participants of a Star Coupler can happen simultaneously , because the Star does not connect the Test signal through, and so to say, each participant tests on its local connection, i.e. participant in the Star, here the Bus 305, 306, 307, and executes the corresponding Loop Back. In this case, thus, through the topology of the Star, an overlapping of the messages or the Testing exercise as part of the monitoring of the Bus Guardian-Function is out of question.
Thus, in contrast to the State-of-the-art of technology, an advantageous extension is achieved, enabling a higher rationalization of the Bus load.
1. Process for verification of a Monitoring Function of a Bus System with at least one participant whereby, first time slots are provided, in which, messages are carried, and from a number of first time slots a Communication cycle is created in such a manner that the messages are carried in the first time slots, whereby, a number of first time slots and the respective position of a first time slot for the messages of the participant in the Communication cycle is visualized; is thereby characterized, that a second time slot after the Communication cycle is provided, in which no messages can be carried, and that the Monitoring function is verified in this second time slot.
2. Process according to Claim 1 is thereby characterized, that the Monitoring function is designed in such a fashion, that the messages of the participant, which are sent outside of the first time slots visualized for these messages, are blocked.
3. Process according to Claim 1 is thereby characterized that in the second time slot, internal protocol tasks of the participant of the Bus system are processed.
4. Process according to Claim 2 is thereby characterized that a Time correction value is ascertained as internal Protocol task, in order to match a local time of the participant to a global time of the Bus system.
5. Process according to Claims 1 and 2 is thereby characterized that the Monitoring function is verified in such a manner that the participant attempts to send a test message in the second time slot and verifies whether this test message was blocked.
6. Process according to Claim 5 above is thereby characterized that the participant can read back the messages sent by himself from the Bus system and thus can carry out himself the verification whether the test message was blocked.
7. Process according to Claim 6 is thereby characterized that the test message possesses an unambiguous Signal form in the Bus system in order to differentiate these from transient beams.
8. Process according to claim 1 is thereby characterized that each participant carries out the verification himself, and the verification of the Monitoring Function can be carried out simultaneously only by one single participant.
9. Process according to; Claim 1 is thereby characterized that each participant is allotted with a third time slot, which lies within the second time slot, in which only the corresponding participant can verify the Monitoring function.
tO.Process according to ; Claim 1 is thereby characterized that each participant is allotted with a second time slot after a Communication cycle, in which only the corresponding participant can verify the Monitoring Function.
11. Process according to Claim 9 or 10 above is thereby characterized that each participant carries put the verification himself.
12. Process according to Claim 5 is thereby characterized that the test message has an unambiguous Signal Form and each participant is allotted with a test message of his own, whereby the test messages of the
individual participants differ from each other.
13. Process according to Claim 11 is thereby characterized that a test message allotted to a participant, can be received only by that one participant.
14. Process according to Claim 5 is thereby characterized that each participant is allotted with a test message or Time slot specifically, and at least a second participant carries out the verification of the Monitoring function of the first participant.
15. Process according to Claim 14 is thereby characterized that at least one of the second participants transmits to the first participant a result of the verification of the Monitoring function of the first participant.
16. Device for verification of a Monitoring function of a Bus system with at least one participant, whereby first time slots are visualized, in which messages are carried and from a number of first time slots a Communication cycle is created in such a manner, that the messages are carried in the first time slots whereby the number of first time slots and the respective position of a first time slot for the messages of the participant in the Communication cycle are predetermined, is thereby characterized that a second time slot is visualized after the Communication cycle, in which no message can be carried and that the requisite means are included, which verify the Monitoring function in this second time slot.
17. Bus system wrth at least one participant for verification of a Monitoring Function, whereby first :tirne slots are visualized in which, messages are carried and from a number of first time slots, a Communication cycle is created in such a manner that the messages are carried in the first time slots, whereby the number of the first time slots and the respective position of a first time slot for the message of the participant are prescribed in the Communication cycle, is thereby characterized, that a second time slot is provided after the Communication cycle, in which no message can be carried and that adequate means are included, which verify the Monitoring function in this second time slot.
18. Device according to Claim 16 or 17 is thereby characterized, that the Bus system has a Star topolbgy and each participant possesses a connection to a Coupling element of the Bus system in Star topology, whereby the Coupling element is so designed that a Test message of a participant is not further transmitted or forwarded through the Coupling element for which the means are included in each participant.
19. A process for verification of a Monitoring Function of a Bus System substantially as herein described with reference to the accompanying drawings.
Process and Device for verification of a Monitoring Function of a Bus system as well as a Bus system, with at least one participant, whereby the first Time slots are provided, in which messages are carried and from a number of first-time slots a Communication cycle is created in such a manner that the messages are carried in the first time slots, whereby the number of first time slots and the respective position of a first time slot for the messages of the participant, are prescribed in the Communication cycle, whereby the second time slot is provided after the Communication cycle, in which no messages are carried and the Monitoring function is verified in this second time slot.
|Indian Patent Application Number||2333/CHENP/2004|
|PG Journal Number||29/2011|
|Date of Filing||14-Oct-2004|
|Name of Patentee||ROBERT BOSCH GmbH|
|Applicant Address||POSTFACH 30 02 20, D-70442 STUTTGART , GERMANY|
|PCT International Classification Number||G06F 13/42|
|PCT International Application Number||PCT/DE03/01246|
|PCT International Filing date||2003-04-14|