System for synchronous measurement in a digital computer network

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.

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.