System for synchronous measurement in a digital computer network

• US 4,982,185 A
• Filed: 05/17/1989
• Issued: 01/01/1991
• Est. Priority Date: 05/17/1989
• Status: Expired due to Term

• Current Assignee: BLH Electronics Incorporated
• Original Assignee: BLH Electronics Incorporated
• Inventors: Holmberg, Rainer, Ordway, Frank S.
• Primary Examiner(s): Yusko, Donald J.
• Assistant Examiner(s): WEISSMAN, PETER
• Application Number:
  US07/353,406
• Time in Patent Office: 594 Days
• Field of Search: 340/825.21, 340/825.2, 340/825.06, 340/825.07, 340/825.08, 340/825.05, 340/825.52, 340/539, 340/870.02, 340/870.03, 340/870.04 , 340/870.06, 370/94.1, 370/85.4, 370/85.5
• US Class Current: 340/4.21
• CPC Class Codes: G05B 2219/37526 Determine time or position to take a measurement
• CPC Class Codes: G05B 2219/37532 Synchronized data acquisition
• CPC Class Codes: H04J 3/0658 Clock or time synchronisation among packet nodes
• CPC Class Codes: H04J 3/0682 by delay compensation, e.g. by compensation of propagation delay or variations thereof, by ranging
• CPC Class Codes: H04L 12/423 with centralised control, e.g. polling

Abstract

A synchronous distributed measurement system in a digital computer network comprising a master node and a plurality of slave nodes interconnected by communications links to form a ring. The master mode includes a message transmitter for transmitting a synchronizing message over a communications link. Each slave node includes an operational portion for performing selected operations. A message receiver receiving the synchronizing message from a communications link, and a message transmitter responsive to receipt of the synchronizing message for retransmitting the synchronizing message over the communications link. An operational control portion starts the measurement portion a selected delay time after the message receiver receives the synchronizing message, the delay time providing that the operational portions of the slave nodes perform the measurements in synchronization.

Claims

1. A synchronous distributed measurement system comprising a master node and a plurality of slave nodes interconnected in sequence by communications links to form a ring,

A. the master node including a message transmitter for transmitting a synchronizing message over the communications links;

B. each slave node including;

i. a measurement portion for performing selected measurements;

ii. a message receiver for receiving the synchronizing message from the master node, the synchronizing message being received initially by the message receiver of the first slave node;

iii. a message transmitter responsive to receipt of the synchronizing message for transmitting the synchronizing message over the communication link to the next slave node, the transmitter of the first slave node passing the synchronizing message to the receiver of the second slave node which along with the subsequent slave nodes repeat the process around the ring so that synchronizing message is sequentially received by all the slave nodes but at different times;

iv. an operational control portion for enabling the measurement portion to perform selected measurements beginning at a different selected delay time after the message receiver receives the synchronizing message for each slave node, the delay time providing that the measurement portions of all the slave nodes perform their respective measurements in synchronization.

2. A system as defined in claim 1 wherein:

A. the master node message transmitter further transmits an auto address message; and

B. the slave node message receiver receives the auto address message, the slave node further including auto address message processor for performing a processing operation in connection with the received auto address message to thereby determine an address for the slave node and to generate a processed auto address message, the slave node message transmitter thereafter transmitting the processed auto address message over the communications link as an auto address message.

3. A system as defined in claim 2 wherein the auto address message includes an address field including an address value, the auto address processor in each slave node incrementing the value in the address field, saving the incremented value as the address of the slave node, the auto address message including the incremented value in the address field comprising the processed auto address message.

4. A system as defined in claim 3 wherein the master node includes a message receiver that receives an auto address message from a communications link, the master node'"'"'s message transmitter thereafter transmitting a parameter message including a slave node number value that identifies the number of slave nodes in the system.

5. A system as defined in claim 4 in which the master node'"'"'s message transmitter includes in the slave node number value the value from the address field of the auto address message received by its message receiver.

6. A system as defined in claim 4 wherein each slave node message receiver receives a parameter message from its communications link and in response thereto saves the slave node number value, the slave node'"'"'s message receiver thereafter transferring the parameter message to the slave node'"'"'s message transmitter for transmission over its communications link.

7. A system as defined in claim 1 wherein each slave node'"'"'s operational control portion determines the respective delay time based on the number of the particular slave nodes in the chain of slave nodes.

8. A system as defined in claim 4 wherein the operational control portion of each slave node further includes a data transfer message generator for generating a data transfer message for transmission by the slave node'"'"'s message transmitter.

9. A system as defined in claim 8 in which the data transfer message includes a data portion including at least one data slot for receiving operational results generated by the measurement portion, the data transfer message generator of the first slave node establishing a first slot and loading its operational results thereinto, each other slave node including a data transfer message portion that, upon receipt of a data transfer message by the slave node'"'"'s message receiver, generates an additional slot and loads its operational results generated by its measurement portion thereinto, and couples the message to its transmitter for transmission to the next slave node.

10. A slave node for use in a synchronous distributed measurement system comprising a plurality of slave nodes interconnected in a ring, each slave node comprising:

A. a measurement portion for performing selected measurements;

B. a message receiver for receiving the synchronizing message from a communications link;

C. a message transmitter responsive to receipt of the synchronizing message for transmitting the synchronizing message over the communications link; and

D. an operational control portion for enabling the measurement portion to perform said selected measurements beginning at a different selected delay time after the message receiver receives the synchronizing message for each slave node, the delay time providing that the measurement portions of all the slave nodes perform their respective measurements in synchronization without any further control signals.

11. A slave node as defined in claim 10 wherein the slave node message receiver receives an auto address message, the slave node further including auto address message processor for performing a processing operation in connection with the received auto address message to thereby determine an address for the slave node and to generate a processed auto address message, the slave node message transmitter thereafter transmitting the processed auto address message over the communications link as an auto address message.

12. A slave node as defined in claim 11 wherein the auto address message includes an address field including an address value, the slave node'"'"'s auto address processor incrementing the value in the address field, saving the incremented value as the address of the slave node, the auto address message including the incremented value in the address field comprising the processed auto address message.

13. A slave node as defined in claim 12 wherein each slave node message receiver receives a parameter message from its communications link and in response thereto saves a slave node number value identifying the number of slave nodes in the system, the slave node'"'"'s message receiver thereafter transferring the parameter message to the slave node'"'"'s message transmitter for transmission over its communications link.

14. A slave node as defined in claim 13, the slave node'"'"'s operational control portion determining the respective delay time using the slave node'"'"'s address value, which the auto address message processor saved during the processing of the auto-address value and the slave node number value from the parameter message.

15. A slave as defined in claim 10 further including a data transfer message generator for generating a data transfer message for transmission by its message transmitter in response to operation by the operational portion.

16. A slave node as defined in claim 15 in which the data transfer message includes a data portion including at least one data slot for receiving operational results generated by the operational portion, the data transfer message generator establishing a first slot and loading operational results thereinto.

17. A slave node as defined in claim 15 including a data transfer message portion that, upon receipt of a data transfer message by its message receiver, generates a slot and loads operational results generated by its operational portion thereinto, and couples the message to its transmitter for transmission.

18. A method of operating a synchronous distributed measurement system comprising a master node and a plurality of slave nodes interconnected by communications links to form a ring, comprising the steps of:

A. the master node transmitting a synchronizing message over a communications link;

B. each slave node;

i. receiving the synchronizing message from a communications link and transmitting the synchronizing message to another slave node over another communications link so that the synchronizing message is sequentially received by all the slave nodes but at different times;

ii. determining, in response to receipt of the synchronizing message, the delay time for each slave node after which the slave node enables its measurement portion to obtain a measurement value, providing that the end of the different delay times determined by all of the slave nodes are coincident; and

iii. each slave node performing the measurement at the end of its delay time.