Automatic can address allocation method

• US 6,216,172 B1
• Filed: 03/26/1998
• Issued: 04/10/2001
• Est. Priority Date: 03/29/1997
• Status: Expired due to Fees

• Current Assignee: Endress+Hauser GmbH+Co (ENDRESS)
• Original Assignee: Endress+Hauser GmbH+Co (ENDRESS)
• Inventors: Eiche, Wolfgang, Kölblin, Robert
• Primary Examiner(s): Rinehart, Mark H.
• Assistant Examiner(s): WILLETT, STEPHAN F
• Application Number:
  US09/048,412
• Time in Patent Office: 1,111 Days
• Field of Search: 709/253, 709/227, 709/228, 709/220, 709/221, 709/222, 709/245, 340/825.52, 710/3, 710/4, 710/200, 710/220, 710/8, 710/9
• US Class Current: 709/253
• CPC Class Codes: H04L 61/5038 for local use, e.g. in LAN or USB networks, or in a controller area network [CAN]
• CPC Class Codes: H04L 61/5092 by self-assignment, e.g. picking addresses at random and testing if they are already in use

Abstract

For automatic CAN address allocation each bus subscriber still to be allocated an address, generates a random value for a provisional address on system power up. On receiving a request to commence address allocation each bus subscriber writes a telegram claiming the provisional address into the CAN send buffer. If a bus subscriber receives a telegram claiming an address which agrees with its own provisional address, a new random value is generated for a provisional address and a telegram claiming this provisional address is written into the CAN send buffer. If the telegram claiming the provisional address is sent before a telegram claiming the same provisional address is received, the provisional address is deposited in the writeable non-volatile memory as the final address.

Claims

1. A method of automatically allocating addresses in a controller area network (CAN) including a plurality of bus subscribers, one of which serves as the controlling station for initiating address allocation, whereby each bus subscriber is assigned a unique serial number memorized in a non-volatile memory of the bus subscriber and each bus subscriber has a writeable non-volatile memory, said method comprising the steps of:

on system power up, each bus subscriber still to be allocated an address generates a first random value for a provisional address;

on receiving a request to commence address allocation sent by the controlling station a telegram claiming the provisional address dictated by the first random value is written into the CAN send buffer of each bus subscriber and a wait is initiated for authorization to access the bus in sending the telegram;

if a bus subscriber receives a telegram claiming an address which fails to agree with its own provisional address, this address is entered into a list of accredited bus subscribers held in a memory of the receiving bus subscriber;

if before sending its own telegram a bus subscriber receives a telegram claiming an address which agrees with its own provisional address, a new first random value is generated for a provisional address and a telegram claiming this provisional address is written into the CAN send buffer;

if the telegram claiming its own provisional address is sent before a telegram of some other bus subscriber claiming the same provisional address is received, its own provisional address is accepted as the final address in the list of accredited bus subscribers and deposited in the writeable non-volatile memory, wherein

on completion of address allocation said controlling station requests all bus subscribers in sequence on the basis of their allocated addresses to send their serial numbers.

2. The method as set forth in claim 1, wherein each bus subscriber generates together with said first random value, a second random value for a delay time, and said telegram claiming said provisional address dictated by said first random value is written into said CAN send buffer on time-out of said delay time dictated by said second random value.

3. The method as set forth in claim 1, wherein each random value is generated by means of a random generator and the starting value for said random generator is derived from said serial number.

4. The method as set forth in claim 1, wherein on power up said controlling station sends a list of reserved addresses.

5. The method as set forth in claim 1, wherein following generation of a random value for a provisional address, this provisional address is compared to said addresses memorized in said list of accredited bus subscribers and, should agreement exist, the generation of said random value is repeated until no agreement is detected with a memorized address.

6. The method as set forth in claim 1, wherein said controlling station requests bus subscribers having attempted to send their serial numbers at the same time to repeat address allocation.

7. The method as set forth in claim 1, wherein, after all bus subscribers have sent their serial numbers, said controlling station requests the user via a computer connected to said controlling station to allocate each bus subscriber a test point designation, or in the case of a multi-channel instrument, for each channel and in that said bus subscribers enter said test point designations allocated to them into their non-volatile memories.

8. The method as set forth in claim 2, wherein each random value is generated by means of a random generator and the starting value for said random generator is derived from said serial number.

9. The method as set forth in claim 2, wherein on power up said controlling station sends a list of reserved addresses.

10. The method as set forth in claim 3, wherein on power up said controlling station sends a list of reserved addresses.

11. The method as set forth in claim 2, wherein following generation of a random value for a provisional address, this provisional address is compared to said addresses memorized in said list of accredited bus subscribers and, should agreement exist, the generation of said random value is repeated until no agreement is detected with a memorized address.

12. The method as set forth in claim 3, wherein following generation of a random value for a provisional address, this provisional address is compared to said addresses memorized in said list of accredited bus subscribers and, should agreement exist, the generation of said random value is repeated until no agreement is detected with a memorized address.

13. The method as set forth in claim 2, wherein said controlling station requests bus subscribers having attempted to send their serial numbers at the same time to repeat address allocation.

14. The method as set forth in claim 2, wherein after all bus subscribers have sent their serial numbers, said controlling station requests the user via a computer connected to said controlling station to allocate each bus subscriber a test point designation, or in the case of a multi-channel instrument, for each channel and in that said bus subscribers enter said test point designations allocated to them into their non-volatile memories.

15. The method as set forth in claim 3, wherein said controlling station requests bus subscribers having attempted to send their serial numbers at the same time to repeat address allocation.

16. The method as set forth in claim 15, wherein after all bus subscribers have sent their serial numbers, said controlling station requests the user via a computer connected to said controlling station to allocate each bus subscriber a test point designation, or in the case of a multichannel instrument, for each channel and in that said bus subscribers enter said test point designations allocated to them into their non-volatile memories.

17. The method as set forth in claim 4, wherein said controlling station requests bus subscribers having attempted to send their serial numbers at the same time to repeat address allocation.

18. The method as set forth in claim 17, wherein after all bus subscribers have sent their serial numbers, said controlling station requests the user via a computer connected to said controlling station to allocate each bus subscriber a test point designation, or in the case of a multi-channel instrument, for each channel and in that said bus subscribers enter said test point designations allocated to them into their non-volatile memories.

19. The method as set forth in claim 5, wherein said controlling station requests bus subscribers having attempted to send their serial numbers at the same time to repeat address allocation.

20. The method as set forth in claim 19, wherein, after all bus subscribers have sent their serial numbers, said controlling station requests the user via a computer connected to said controlling station to allocate each bus subscriber a test point designation, or in the case of a multi-channel instrument, for each channel and in that said bus subscribers enter said test point designations allocated to them into their non-volatile memories.

21. The method as set forth in claim 6, wherein, after all bus subscribers have sent their serial numbers, said controlling station requests the user via a computer connected to said controlling station to allocate each bus subscriber a test point designation, or in the case of a multi-channel instrument, for each channel and in that said bus subscribers enter said test point designations allocated to them into their non-volatile memories.