Safety device for diagnostic terminals in distributed computer networks

• US 6,351,828 B1
• Filed: 09/28/1998
• Issued: 02/26/2002
• Est. Priority Date: 02/17/1997
• Status: Expired due to Fees

• Current Assignee: Mecel AB (Aptiv PLC)
• Original Assignee: Mercel AB
• Inventors: Lundqvist, Anders, Frimodig, Hans-Ove
• Primary Examiner(s): Iqbal, Nadeem
• Application Number:
  US09/155,387
• Time in Patent Office: 1,247 Days
• Field of Search: 714/43, 714/44, 714/46, 714/47, 714/48, 714/4, 714/25, 714/27, 714/31, 714/721, 714/735, 714/742, 709/201, 709/203, 709/217, 709/250
• US Class Current: 714/43
• CPC Class Codes: B60R 16/0315 using multiplexing techniques multiplexing for transmission of signals G08C15/00; multiplexing for electrical communication in general H04J
• CPC Class Codes: B60R 2016/0322 Temporary code for documents to be reclassified to G08C, H04L or H04Q

Abstract

A safety device for diagnostic terminals (3) in distributed computer networks (8) containing at least two nodes and a common communication bus (10a, 10b) for the computer network, preferably implemented in vehicles. The diagnostic terminal enables connection of an external diagnostic equipment (1) to different nodes (20a, 20b, 20c) within the computer network. By a signal evaluation circuit (12) arranged in the computer network a detection of the signal state at the contact pin or pins (3a, 3b) in the diagnostic terminal can be made, which contact pins connect the diagnostic equipment to the communication bus. A predetermined signal state will indicate an authorized connection of a diagnostic equipment (1), and only after an authorized connection will a direct connection to the communication bus (10a, 10b) be established via a relay function (13, 14a, 14b).

Claims

1. A safety device for a diagnostic terminal for a distributed computer network containing at least two nodes and a common communication bus for the computer network, which diagnostic terminal includes a first set of contact pins for access to the communication bus and is connectable to an external diagnostic equipment for performing diagnostics on the nodes within the computer network, the safety device comprising:

switches which, in a first stable position, connect the first set of contact pins to the communication bus and, in a second stable position, disconnect the first set of contacts from the communication bus; and

a signal evaluation circuit connected to the first set of contact pins and arranged to enable detection of a predetermined signal state from the diagnostic equipment at the first set of contact pins and, when a predetermined signal state occurs, causes the switches to switch from the second stable position to the first stable position to connect the first set of contact pins to the communication bus, so that the diagnostic equipment connected to the diagnostic terminal may obtain direct access to the communication bus, the diagnostic equipment applying the predetermined signal state to a second set of contact pins connected with said first set of contact pins when the diagnostic equipment is connected to the diagnostic terminal and the signal evaluation circuit including a detection device which, dependent on a specific voltage level within a predetermined voltage range applied on at least one of the first set of contact pins, will activate the switches and at least two comparators each comparing the voltage applied on at least one of the first set of contact pins with first and second reference voltages, respectively, which first and second reference voltages are obtained from a voltage divider.

4. A safety device according to claims 1, 2 or 3, wherein the diagnostic equipment includes signal circuits which apply a voltage within the predetermined voltage range to at least one of the first set of contact pins when the diagnostic equipment is connected to the diagnostic terminal.

2. A safety device for a diagnostic terminal for a distributed computer network containing at least two nodes and a common communication bus for the computer network, which diagnostic terminal includes a first set of contact pins for access to the communication bus and is connectable to an external diagnostic equipment for performing diagnostics on the nodes within the computer network, the safety device comprising:

switches which, in a first stable position, connect the first set of contact pins to the communication bus and, in a second stable position, disconnect the first set of contacts from the communication bus switches; and

a signal evaluation circuit connected to the first set of contact pins and arranged to enable detection of a predetermined signal state from the diagnostic equipment at the first set of contact pins and, when a predetermined signal state occurs, causes the switches to switch from the second stable position to the first stable position to connect the first set of contact pins to the communication bus, so that the diagnostic equipment connected to the diagnostic terminal may obtain direct access to the communication bus, the signal evaluation circuit including a detection device which, dependent on a specific voltage level within a predetermined voltage range applied on at least one of the first set of contact pins, will activate the switches and at least two comparators each comparing the voltage applied on at least one of the first set of contact pins with first and second reference voltages, respectively, which first and second reference voltages are obtained from a voltage divider, the switches being relay contacts which are switched by a relay activated by the signal evaluation circuit.

3. A safety device for a diagnostic terminal for a distributed computer network containing at least two nodes and a common communication bus for the computer network, which diagnostic terminal includes a first set of contact pins for access to the communication bus and is connectable to an external diagnostic equipment for performing diagnostics on the nodes within the computer network, the safety device comprising:

semiconductor switches which, in a first stable position, connect the first set of contact pins to the communication bus and, in a second stable position, disconnect the first set of contacts from the communication bus; and

a signal evaluation circuit connected to the first set of contact pins and arranged to enable detection of a predetermined signal state from the diagnostic equipment at the first set of contact pins and, when a predetermined signal state occurs, causes the switches to switch from the second stable position to the first stable position to connect the first set of contact pins to the communication bus, so that the diagnostic equipment connected to the diagnostic terminal may obtain direct access to the communication bus, the signal evaluation circuit including a detection device which, dependent on a specific voltage level within a predetermined voltage range applied on at least one of the first set of contact pins, will activate the switches and at least two comparators each comparing the voltage applied on at least one of the first set of contact pins with first and second reference voltages, respectively, which first and second reference voltages are obtained from a voltage divider.

5. A safety device for a diagnostic terminal for a distributed computer network containing at least two nodes and a common communication bus for the computer network, which diagnostic terminal includes a first set of contact pins for access to the communication bus and is connectable to an external diagnostic equipment for performing diagnostics on the nodes within the computer network, the safety device comprising:

switches which, in a first stable position, connect the first set of contact pins to the communication bus and, in a second stable position, disconnect the first set of contacts from the communication bus; and

a signal evaluation circuit connected to the first set of contact pins and arranged to enable detection of a predetermined signal state from the diagnostic equipment at the first set of contact pins and, when a predetermined signal state occurs, causes the switches to switch from the second stable position to the first stable position to connect the first set of contact pins to the communication bus, so that the diagnostic equipment connected to the diagnostic terminal may obtain direct access to the communication bus, the diagnostic equipment applying the predetermined signal state to a second set of contact pins connected with said first set of contact pins when the diagnostic equipment is connected to the diagnostic terminal and the signal evaluation circuit including;

an interface capable of detection of at least one initiating message sent on the communication bus, which initiation message is compatible with a communication protocol used for messages sent on the communication bus but is unique in relation to any other type of message being sent on the communication bus;

a memory containing a unique authorization code for the computer network; and

a comparison circuit for comparing the initiating message detected by the interface with the authorization code stored in the memory and, if a match occurs between the initiating message and the authorization code stored in the memory, establishes a direct access from the diagnostic terminal to the communication bus by switching the switches to the first stable position.

8. A safety device according to claims 5, 6 or 7, wherein the memory is a non-volatile memory.

6. A safety device for a diagnostic terminal for a distributed computer network containing at least two nodes and a common communication bus for the computer network, which diagnostic terminal includes a first set of contact pins for access to the communication bus and is connectable to an external diagnostic equipment for performing diagnostics on the nodes within the computer network, the safety device comprising:

switches which, in a first stable position, connect the first set of contact pins to the communication bus and, in a second stable position, disconnect the first set of contacts from the communication bus; and

a signal evaluation circuit connected to the first set of contact pins and arranged to enable detection of a predetermined signal state from the diagnostic equipment at the first set of contact pins and, when a predetermined signal state occurs, causes the switches to switch from the second stable position to the first stable position to connect the first set of contact pins to the communication bus, so that the diagnostic equipment connected to the diagnostic terminal may obtain direct access to the communication bus, the switches being relay contacts which are switched by a relay activated by the signal evaluation circuit and the signal evaluation circuit including;

an interface capable of detection of at least one initiating message sent on the communication bus, which initiation message is compatible with a communication protocol used for messages sent on the communication bus but is unique in relation to any other type of message being sent on the communication bus;

a memory containing a unique authorization code for the computer network; and

a comparison circuit for comparing the initiating message detected by the interface with the authorization code stored in the memory and, if a match occurs between the initiating message and the authorization code stored in the memory, establishes a direct access from the diagnostic terminal to the communication bus by switching the switches to the first stable position.

7. A safety device for a diagnostic terminal for a distributed computer network containing at least two nodes and a common communication bus for the computer network, which diagnostic terminal includes a first set of contact pins for access to the communication bus and is connectable to an external diagnostic equipment for performing diagnostics on the nodes within the computer network, the safety device comprising:

semiconductor switches which, in a first stable position, connect the first set of contact pins to the communication bus and, in a second stable position, disconnect the first set of contacts from the communication bus; and

a signal evaluation circuit connected to the first set of contact pins and arranged to enable detection of a predetermined signal state from the diagnostic equipment at the first set of contact pins and, when a predetermined signal state occurs, causes the switches to switch from the second stable position to the first stable position to connect the first set of contact pins to the communication bus, so that the diagnostic equipment connected to the diagnostic terminal may obtain direct access to the communication bus the signal evaluation circuit including;

an interface capable of detection of at least one initiating message sent on the communication bus, which initiation message is compatible with a communication protocol used for messages sent on the communication bus but is unique in relation to any other type of message being sent on the communication bus;

a memory containing a unique authorization code for the computer network; and

a comparison circuit for comparing the initiating message detected by the interface with the authorization code stored in the memory and, if a match occurs between the initiating message and the authorization code stored in the memory, establishes a direct access from the diagnostic terminal to the communication bus by switching the switches to the first stable position.