Method for initializing a token-passing local-area network

• US 4,551,721 A
• Filed: 10/07/1983
• Issued: 11/05/1985
• Est. Priority Date: 10/07/1983
• Status: Expired due to Term

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Inventors: Kozlik, Tony J.
• Primary Examiner(s): YUSKO, DONALD
• Application Number:
  US06/540,216
• Time in Patent Office: 760 Days
• Field of Search: 340/825.05, 340/825.5, 340/825.16, 340/825.52, 370/85, 370/86
• US Class Current: 370/452
• CPC Class Codes: H04L 12/417 with deterministic access, e.g. token passing

Abstract

The method by which a token-passing local-area network having from two to 2ⁿ modules is initialized, where n is an integer greater than zero. When connected into the network and energized, each module determines if the network is initialized and, if not, which module is to do so. Each module has a unique n bit network address. The module with the smallest network address energized before the network is initialized is identified and begins the process of initialization by transmitting tokens addressed sequentially to network addresses beginning with the next higher address than its own until a token so transmitted is accepted by an addressed module or until a token has been addressed to all network addresses other than that of the initiating module. If after tokens are transmitted to all possible network addresses other than that of the initiating module, the initiating module generates a fault signal to indicate its status.

Claims

1. The method of initializing a token-passing local-area network which includes a plurality of modules communicating with one another over a common bus, with each module having a unique network address, comprising the steps of:

(1) each module listening for a predetermined period of time for any transmissions of signals on the bus;

(2) transmitting, if no signals are heard during step 1, for a period of time which is a function of each module'"'"'s address;

(3) listening after a fixed delay for a fixed period of time after terminating transmission under step 2;

(4) the module that hears nothing in step 3, transmitting tokens sequentially addressed to each network address until a token is accepted by an addressed module; and

(5) the module performing step 4 producing a fault signal and terminating initializaton if the network address of a token to be transmitted in step 4 is that of the module performing step 4.

2. The method of initializing a token-passing local-area network in which the network comprises a plurality of electronic modules communicating with one another over a common bus, with each module having a unique network address, its MY ADDRESS, comprising the steps of:

(1) each module sensing if any signals are transmitted over a bus for a first period of time;

(2) each module transmitting signals, if no signals are sensed during step 1, over the bus for a period of time which is a function of each module'"'"'s address;

(3) each module after completing step 2 determining after a predetermined delay during a second period of time if any signals are transmitted over the bus;

(4) the module that does not sense any signals during step 3, the initiating module, transmitting a token addressed to a module whose address is that of the transmitting module modified by one;

(5) the initiating module determining if the token transmitted in step 4 is accepted by a module to which the token is addressed;

(6) if the token is not accepted by the addressed module, incrementing the address of the token by one;

(7) determining if the incremented address of the token equals the address of the initiating module;

(8) transmitting a token with the incremented address if the incremented address does not equal the address of the initiating module and determining if the token transmitted is accepted by a module;

(9) repeating steps 6, 7 and 8 until a token is accepted by an addressed module or the incremented address equals the address of the initiating module;

(10) terminating initialization when a module accepts a token; and

(11) issuing an interrupt signal if the incremented address of a token equals the address of the initiating module.

3. The method of initializing a token-passing local-area network which can include up to 2ⁿ bits of electronic modules where "n" is an integer other than zero, communicating with one another over a common bus, with each module having its own unique n bit MY ADDRESS and the capability of forming and identifying its n bit LAST SUCCESS ADDRESS, comprising the steps of:

(1) each module sensing if any binary signals are transmitted over the bus during a first period of time;

(2) any module terminating initialization if it senses any signals in step 1;

(3) each module not terminating initialization in step 2 transmitting binary signals over the bus for a period of time which is an inverse function of its MY ADDRESS;

(4) each module performing step 3 sensing for a third period of time after a delay for a second period of time if any binary signals are being transmitted over the bus;

(5) each module performing step 4 terminating initialization if it senses any binary signals being transmitted on the bus during said third period;

(6) the module not terminating initialization in step 5, the initializing module, setting its LAST SUCCESS ADDRESS to equal its MY ADDRESS plus one and transmitting a token addressed to its LAST SUCCESS ADDRESS;

(7) the initializing module terminating initialization if the token transmitted in step 6 is accepted by the addressed module;

(8) the initializing module transmitting a token addressed to its LAST SUCCESS ADDRESS a second time if the token transmitted in step 6 is not accepted by the addressed module;

(9) the initializing module terminating initialization if the token transmitted in step 8 is accepted by the addressed module;

(10) the initializing module incrementing its LAST SUCCESS ADDRESS and transmitting a token addressed to its incremented LAST SUCCESS ADDRESS if the token transmitted in step 8 is not accepted by the addressed module;

(11) terminating initialization if the token transmitted in step 10 is accepted by the addressed module;

(12) repeating step 10 until a token is accepted by an addressed module or the incremented LAST SUCCESS ADDRESS equals its MY ADDRESS; and

(13) generating an alone in the ring interrupt if the incremented LAST SUCCESS ADDRESS of step 10 equals the initializing module'"'"'s MY ADDRESS.

4. The method of claim 3 in which n=seven.

5. The method of claim 4 in which the first period of time is substantially 25 microseconds.

6. The method of claim 5 in which the second period of time is substantially four microseconds.

7. The method of claim 6 in which the third period of time is substantially 5.8 microseconds.