Bus-driveable sensor apparatus with direction-dependent current/voltage characteristic curve and method for testing the apparatus

• US 6,563,326 B1
• Filed: 12/19/2000
• Issued: 05/13/2003
• Est. Priority Date: 07/09/1998
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Huebsch, Thomas
• Primary Examiner(s): Oda, Christine
• Assistant Examiner(s): Hamdan, Wasseem H.
• Application Number:
  US09/720,014
• Time in Patent Office: 875 Days
• Field of Search: 324/609, 324/767, 361/6, 340/505, 340/10.4
• US Class Current: 324/609
• CPC Class Codes: G01D 21/00 Measuring or testing not otherwise provided for
• CPC Class Codes: G08B 26/005 with substations connected in series, e.g. cascade
• CPC Class Codes: G08B 29/14 checking the detection circuits

Abstract

The current invention provides a bus-drivable sensor apparatus (10) having a first and a second bus input (a1, b1) for connecting to a corresponding first and second bus line (B⁻, B⁺), which have a corresponding first and second potential in normal bus operation; a control device (100), which is connected to the first and second bus input (a1, b1); a sensor contact (50) with at least two different contact states, which is connected on its first connection to the first bus input (a1); and a sensor contact state detecting device (150), which is connected to the second connection of the sensor contact (50) and the control device (100) in order to detect the contact state of the sensor contact (50) and to transmit this information to the control device (100); wherein the control device (100) is embodied in such a way that it reacts to a certain transmitted contact state by triggering a predetermined control function. A switching element with a direction-dependent current/voltage characteristic curve (SE; D1) is designed and connected between the second connection of the sensor contact (50) and the second bus input (b1) in such a way that it essentially does not influence the normal bus operation, independent of the contact state of the sensor contact (50). This provides a simple possibility for testing the sensor contact.

Claims

1. A bus-drivable sensor apparatus (10) having:

a first and a second bus input (a1, b1) for connecting to a corresponding first and second bus line (B⁻

, B⁺), which have a corresponding first and second potential in normal bus operation;

a control device (100), which is connected to the first and second bus input (a1, b1);

a sensor contact (50) with at least two different contact states, which is connected on its first connection to the first bus input (a1); and

a sensor contact state detecting device (150), which is connected to the second connection of the sensor contact (50) and the control device (100) in order to detect the contact state of the sensor contact (50) and to transmit this information to the control device (100);

wherein the control device (100) is embodied in such a way that it reacts to a certain transmitted contact state by triggering a predetermined control function;

characterized by means of

a switching element with a direction-dependent current/voltage characteristic curve (SE;

D1), which is designed and connected between the second connection of the sensor contact (50),and the second bus input (b1) in such a way that it essentially does not influence the normal bus operation, independent of the contact state of the sensor contact (50).

2. The bus-drivable sensor apparatus (10), according to claim 1, characterized in that the switching element with the direction-dependent current/voltage characteristic curve (SE;

D1) is wired in.such a way that in a testing operation, in which the first and second bus input (a1, b1) are connected to a third and fourth potential that have a potential difference with a different sign than the first and second potential, a current/voltage characteristic curve that is a function of the contact state of the sensor contact (50) can be detected at the first and second bus input (a1, b1).

3. The bus-drivable sensor apparatus (10) according to claim 1, characterized in that the switching element with the direction-dependent current/voltage characteristic curve (SE;

D1) is a first diode device (D1), which is connected with its positive connection to the second connection of the sensor contact (50) and is connected with its negative connection to the second bus input (b1), wherein the first potential is lower than the second potential.

4. The bus-drivable sensor apparatus (10) according to claim 3, characterized in that the control device has a second diode device (D2), in particular as an electromagnetic compatibility safety device, which is connected in parallel to the first diode device (D1) in a contact state of the sensor contact (50) and that the threshold voltage of the first diode device (D1) is lower than the threshold voltage of the second diode device (D2).

5. The bus-drivable sensor apparatus (10) according to claim 1, characterized in that the control device (100) is embodied in such a way that it reacts to a particular transmitted contact state by sending a message via the bus.

6. The bus-drivable sensor apparatus (10) according to claim 1, characterized in that a first and second bus output (a1′

, b1′

), which are connected to the control device (100), are provided for connecting to another first and second bus line (B⁻

, B⁺).

7. The bus-drivable sensor apparatus (10) according to claim 6, characterized in that an addressing device (20a;

20b) is provided, which is disposed between the second bus input (b1) and the second bus output (b1′

).

8. The bus-drivable sensor apparatus (10) according to claim 1, characterized in that the sensor contact (50) is a switch element, in particular a reed switch, thermal circuit breaker, induction switch, or optical switch.

9. A testing method for testing a sensor contact (50) of a bus-drivable sensor apparatus (10), including the following steps:

uncoupling of the sensor apparatus (10) from a bus (B⁺, B⁻

);

measuring a current/voltage characteristic curve at a first and second bus input (a1, b1) in a testing operation, in which the first and second bus input (a1, b1) are connected to a third and fourth potential that have a potential difference with a different sign than a first and second potential in different contact states of the sensor contact (50) by using a multimeter; and

assessing quality of the sensor contact (50) based on a measurement result.

10. The testing method according to claim 9, characterized in that the sensor contact (50) has two contact states, open and closed, and the current/voltage characteristic curve is measured at the first and second bus input (a1, b1) in these two states.