US 4,943,963 A · Data collection and transmission system with real time clock

Abstract

A communication method and a data collection and transmission system are provided having at least one remotely located monitoring station. A central computer is arranged for bidirectional communication with each of the monitoring stations. Each of the monitoring stations includes a storage and forward unit for communicating with the central computer and at least one sensor unit for monitoring a predetermined geographically proximate variable and for processing and storing predetermined operational data. The storage and forward unit includes a real time clock that is arranged to accurately maintain a real time indicative signal. A local area network connects the storage and forward unit and each of the sensor units. A coded message having a predetermined sequential data format is used for bidirectional communications between the storage and forward unit and the sensor units. A real-time coded message is provided by the storage and forward unit to the sensor units. The storage and forward unit includes a counter for counting at a predefined rate for identifying a delay time period prior to the transmission of the real-time coded message. Each sensor unit includes a counter for counting at the predefined rate to identify a second time delay period responsive to a received real-time coded message from the storage and forward unit. The real-time coded message includes the first identified time delay period that is combined with the second identified time delay period to determine the current time value by the sensor unit.

Claims42

Dependent claims

A data collection and transmission system comprising:

at least one remotely located monitoring station for collecting and storing predetermined operational data;
a central computer arranged for bidirectional communication with said monitoring station and for processing said stored predetermined operational data;
said at least one remotely located monitoring station including a storage and forward unit for communicating with said central computer and having a real time clock, at least one sensor unit for monitoring and storing predetermined operational data and a local area network connecting said storage and forward unit and each of said sensor units;
and
said at least one sensor unit including means for receiving a real time coded message from said storage and forward unit, and means responsive to said received real time coded message for determining a current time value, said current time value determining means including means for identifying a transmission time delay over said local area network, and means responsive to said identified transmission time delay for adjusting said real time coded message.

2 more elements

A method for identifying a transmission time delay of a predefined coded message transmitted over a local area network comprising the steps of:

reading a real time clock to identify a current time data value;
initializing a first duration counter within a transmitting unit responsive to said identified current time data value;
transmitting a start of message byte of the predefined coded message;
reading said first duration counter responsive to said transmitted start of message byte;
transmitting said read first duration counter value in a predefined message header byte of the predefined coded message;
initializing a second duration counter within a receiving unit responsive to a received start of message byte;
reading said second duration counter responsive to a received data packet checksum byte of the predefined coded message;
identifying said first duration counter value of the predefined message header byte of the predefined coded message;
and
combining said first and second duration counter values.

7 more elements

Dependencies are inferred from the claim text.

Data collection and transmission system with real time clock

Life of this patent

Data collection and transmission system with real time clock

Life of this patent

Abstract

Claims42