System using a variable timer to optimally adjust issuing a start data collection signal at near the beginning of data transmission signal

• US 5,862,411 A
• Filed: 06/10/1996
• Issued: 01/19/1999
• Est. Priority Date: 06/10/1996
• Status: Expired due to Term

• Current Assignee: Allen-Bradley Company (Rockwell Automation, Inc.)
• Original Assignee: Allen-Bradley Company (Rockwell Automation, Inc.)
• Inventors: Kay, James J., Boldt, Peter J.
• Primary Examiner(s): Luu, Le Hien
• Application Number:
  US08/664,967
• Time in Patent Office: 953 Days
• Field of Search: 395/557, 395/878, 395/826, 395/849, 395/559, 375/354, 370/448, 370/248, 250/374, 307/141
• US Class Current: 710/58
• CPC Class Codes: G06F 1/14 Time supervision arrangements, e.g. real time clock

Abstract

A controller based network, where data from a plurality of nodes is placed onto the network in a scheduled predetermined order during a network update interval. The data transmitted onto the network being collected following the issuance of a data collection start signal issued in accordance with a timer, whereby the issuance of the data collection start signal can be varied within the network update interval. The collected data being transmitted onto the network upon the issuance of a data transmission signal.

Claims

1. A controller based network comprising:

a sensor configured to sense and acquire data representing a state of a device or event with which the sensor is associated;

an input/output device in operative connection with the sensor, the input/output device receiving the data acquired by the sensor;

a controller in operative connection with the input/output device so as to receive the data and generate commands based on the received data including commands for transmission of the data scheduled to be transmitted during a network update interval, the controller further including a data collection start signal generator which issues a data collection start signal; and

a timer having an adjustable time-out period, wherein when the timer reaches the time-out period the data collection start signal is issued, and wherein the timer is configured such that the time-out period is reached sufficiently ahead of a start of a next network update interval to allow all of the scheduled data to be collected for transmission by the controller.

2. The network according to claim 1 wherein the time-out period of the timer is adjustable.

3. The network according to claim 1 wherein the timer is a part of the controller.

4. The network according to claim 1 wherein the timer is independently constructed from the controller.

5. The network according to claim 1 wherein data is placed onto the network in a structured manner to avoid collisions of different data attempting to gain access to the network.

6. The network according to claim 5 wherein the data is provided from a plurality of nodes and data from each of the nodes is placed onto the network in a predetermined scheduled order.

7. The network according to claim 6 wherein the data from the plurality of nodes is provided onto the network during a network update interval.

8. The network according to claim 1 wherein use of the timer results in a maximum data input to output time of approximately 28 milliseconds and an average data input to output time of approximately 23 milliseconds.

9. A controller based network comprising:

a sensor which acquires data representing a state of a device or event;

an input/output device in operative connection with the sensor for receiving the data; and

,

a controller in operative connection with the input/output device, including a program which generates a data transmission signal issued to begin transmission of the data acquired by the sensor onto the controller based network and scheduled to be transmitted during a network update interval; and

,

a timer which functions to generate a data collection start signal issued at an adjustable time after the start of the network update interval, and wherein the timer is configured such that the time-out period is reached sufficiently ahead of a start of a next network update interval, to allow all of the scheduled data to be collected for transmission by the controller.

10. The network according to claim 9 wherein the data provided to the network during a network update interval is sent to the network according to a predetermined scheduled order.

11. The network according to claim 10 wherein the network update interval time is a set constant value.

12. The network according to claim 10 wherein the data is from a plurality of nodes, such that data from a first node is placed onto the network before data from a second node.

13. The network according to claim 12 wherein data from the plurality of nodes is sent to the network during a network update time which can vary.

14. The network according to claim 13 wherein the data collection start signal is set to issue approximately one millisecond prior to issuance of the data transmission signal.

15. The network according to claim 9 wherein use of the timer results in a maximum data input to output time of approximately 28 milliseconds and an average of approximately 23 milliseconds.

16. A method of transmitting data in a controller based network, the method comprising the steps of:

sensing by a sensor, data of a device or event;

providing the data to an input/output device of the controller based network;

issuing a time variable data collection start signal, during a network update interval;

collecting the data to be transmitted onto the network;

forming the collected data into transmission data to be transmitted onto the network during the network update interval, wherein the time variable data collection start signal is issued sufficiently ahead of a next network update interval to allow all of the data scheduled for transmission to be formed into the transmission data;

issuing a data transmission signal to begin transmission of data onto the network; and

,

transmitting the transmission data onto the network following the issuance of the data transmission signal.

17. The method according to claim 16 wherein the network update interval is a set time period.

18. The method according to claim 16 wherein the data collection start signal is issued 1 millisecond before the data transmission signal.

19. The method according to claim 18 wherein the data collection start signal and data transmission signal are issued during a network update interval.