Master-slave communication system for stations having timer means

• US 4,988,989 A
• Filed: 10/25/1988
• Issued: 01/29/1991
• Est. Priority Date: 10/26/1987
• Status: Expired due to Term

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Goto, Tadaomi
• Primary Examiner(s): Yusko, Donald J.
• Assistant Examiner(s): Magistre, Dervis
• Application Number:
  US07/261,937
• Time in Patent Office: 826 Days
• Field of Search: 340/825.21, 340/825.2, 340/825.52, 340/825.05, 340/825.07, 340/825.14, 340/825.53, 340/825.54, 370/66, 370/88, 370/85, 370/100, 370/85.1, 370/85.12, 370/100.1, 370/106, 375/110, 375/111, 375/114, 375/100, 358/84, 328/72, 370/85.1, 370/85.12, 370/100.1, 370/106
• US Class Current: 340/4.21
• CPC Class Codes: G05B 19/054 Input/output
• CPC Class Codes: H04L 12/403 with centralised control, e.g. polling
• CPC Class Codes: H04L 2012/4026 Bus for use in automation systems

Abstract

A main station has a first timer device and each of a plurality of peripheral stations connected to the main station, through a communication line, has a second timer device. Data is transmitted between each of the plurality of peripheral stations and the main station, with every unit period of communication and the order of the communication therebetween being predetermined. In the unit period of communication mentioned above, an initializing data signal is transmitted from the main station to each of the peripheral stations and a data signal is transmitted between the main station and each peripheral station every individual communication period of each of the peripheral stations.

Claims

1. A data transmission and receiving communication system for communicating data between a main station and each of a plurality of peripheral stations during an identifiable period of time, said system comprising:

a main station including a first timer device for sequentially identifying each of the plurality of peripheral stations with which said main station is communicating data;

a plurality of peripheral stations, each including a second timer device, each being connected to said main station through a common communication line, each said second timer device for initiating data communication between said main station and each corresponding peripheral station every communication unit period, with the order of the communications between the main station and each of the peripheral stations being predetermined and a data communication between the main station and each of the peripheral stations occurring during sequential intervals of said communication unit period, each interval of equivalent time duration;

and wherein, upon each said second timer means counting a designated period of time, determining on the basis of the predetermined communication order of each of the peripheral stations and said equivalent time duration of each interval of said communication unit period, initiating the data communication between the main station and each of the peripheral stations, and

said main station identifying the peripheral station under communication of data by a sequential time counted by the first timer device.

2. The communication system of claim 1, wherein said communication unit period includes intervals of a synchronizing word and a plurality of data words, the number of which corresponds to the number of the peripheral stations.

3. The communication system of claim 1, wherein condition data of existance of a connection between the main station and each of the peripheral stations can be written and renewed into the main station.

4. The communication system of claim 1, wherein each of said second timer device of said peripheral stations are initialized prior data communication and each peripheral station is further identified in status as one of an input and output device.

5. The communication step of claim 4, wherein data transmission involves the main station receiving data from an input device and transmitting data to a peripheral station identified as an output device.

6. The communication system of claim 4, wherein the main station further comprises:

connection reconfirming means for periodically confirming connection of each of said plurality of peripheral stations with said main station, for confirming the status of each of said plurality of peripheral stations as one of an input and output device, and finally for detecting any change in status.

7. The communication system of claim 6, wherein, upon determination of status and any change in status, said data communication being one of a peripheral station, designated as an input device, receiving data from said main station and a peripheral station, designated as an output device, sending data to said main station.

8. The communication system of claim 5, wherein said main station is a robotic device and said peripheral stations are various input and output peripheral devices.

9. A method of data communication between a main station and a plurality of substations, each connected to said main station by a common communication line, comprising the steps of:

(a) preparing each of said plurality of substations for data communication with said main station by.

(1) identifying each of said substations,

(2) designating a predetermined time period for data communication between said main station and each of said plurality of substations, and

(3) storing said identification and designated information at said main station;

(b) communicating data, along said common communication line, between said main station and each of said plurality of substations by,

(1) selecting each of said plurality of substations, in a sequential order, for data communication between said selected substation and said main station,

(2) counting said predetermined time period of step (a)(2), by means of a first timer at said main station for data communication between said main station and each selected substation, said predetermined time period being equal for all of said plurality of substations,

(3) initiating data communication at each of said plurality of substations upon each said substation being activated by means of a second timer located at each of said plurality of substations, each of said second timers activating each said substation after counting a time corresponding to its substation identification number minus one, multiplied by the predetermined time period of said first timer;

(4) communicating data during said predetermined time period of said first timer,

(5) selecting by said main station, a next sequential substation upon completion of said counting of a predetermined time by said first timer;

(c) reconfirming a communication between said main station and each of said plurality of substations by sequentially checking that each of said plurality of substations remains connected to said main station through said common communication line.

10. A method, as claimed in claim 9, wherein said identifying step (1) of the preparation (a) includes:

(a) designating an identification number for each of said plurality of substations, in a sequential numerical order,

(b) identifying a status of each of said plurality of substations as one of an input and an output device,

(c) storing said identification numbers and said identified status for each of said plurality of substations as one of an input and output device, in a tabular format at said main station.

11. A method, as claimed in claim 10, wherein said reconfirming step (c) of claim 7 includes:

(1) reconfirming the status of each of the plurality of substations as being one of an input and an output device, and

(2) correcting said stored tabular data for each of said plurality of substations for which there has been a change in station and storing a new status in place of the previously stored status in said tabular format.

12. A method, as claimed in claim 10, wherein said data communication step (b) dictates one of said main station receiving data from an input device and said main station sending data to an output device.

13. A method as claimed in claim 9, wherein said main station is a robotic device and said plurality of substations are peripheral devices.

14. A method, as claimed in claim 9, wherein said main station can identify which of said substations is communicating data on the basis of said time counted by said first timer at said main station.

15. A method of data communication between a main station and a plurality of substations, along a common communication line connecting the main station and each of the plurality of substations, comprising the steps of:

(a) initializing a first timer device at said main station;

(b) assigning a substation identification number to each of said plurality of substations;

(c) predetermining a selected period of time for which data communication may occur between a selected substations and said main station;

(d) initializing a second timer device at each of said substations;

(e) communicating data between a selected substation and said main station for said predetermined selected period of time, said main station allowing for data communication with said selected substation based on a time counted by the first timer device and said selected substation simultaneously, and independent of the main station and first timer, allowing for data communication with said main station based solely upon said second timer device for said selected substation reaching a count equal to the substation identification number minus one, multiplied by said predetermined period of time;

(f) incrementing a substation identification counting device by one at the end of said predetermined period of time as indicated by said first timer device;

(g) repeating steps e-f a plurality of times, equal in number to said plurality of substations, such that data communication will occur between each of said plurality of substations and said main station for an equal period of time, each equal to said predetermined selected period of time, in a sequential manner.

16. A method as claimed in claim 15, wherein said main station initially identifies each of said plurality of substations as one of an input device and an output device.

17. A method, as claimed in claim 16, wherein upon data communication occurring between a selected substation and said main station, if said substation is identified as an input device then data is sent from said input device to said main station during the step (e) of communicating data and, if said substation is identified as an output device then data is sent from main station to said output device during the step (e) of communicating data.