CSMA type communication system

• US 5,214,647 A
• Filed: 02/08/1991
• Issued: 05/25/1993
• Est. Priority Date: 02/08/1990
• Status: Expired due to Term

• Current Assignee: NEC Electronics Corporation (Renesas Electronics Corporation)
• Original Assignee: NEC Corporation
• Inventors: Komatsu, Yuji
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): TON, DANG T
• Application Number:
  US07/652,519
• Time in Patent Office: 837 Days
• Field of Search: 370/85.3, 370/85.1, 370/85.2, 370/85.6, 370/100.1, 370/91, 370/92, 370/93, 340/825.05, 340/825.52, 340/825.5, 340/825.51, 340/825.27, 340/825.47, 375/8, 379/280
• US Class Current: 370/445
• CPC Class Codes: H04J 3/0685 Clock or time synchronisation in a node; Intranode synchronisation
• CPC Class Codes: H04L 12/18 for broadcast or conference , e.g. multicast
• CPC Class Codes: H04L 12/413 with random access, e.g. carrier-sense multiple-access with collision detection [CSMA-CD]
• CPC Class Codes: H04L 7/08 the synchronisation signals recurring cyclically

Abstract

A CSMA type transmission system for transmitting digital data among a data processing unit and a number of units connected to a bus, each of the units including a storage for storing an own inherent address data, a group address data common to a plurality of data collecting units and a data-bit position data designated inherently to the units belonging to the same group; an address comparator for comparing a master address or a slave address in a transmission frame on the bus with the group address data; a bit position comparator for counting a synchronous signal at a data portion in the transmission frame and comparing the synchronous signal with the data-bit position data; and a data transmitter for transmitting data synchronously with the synchronous signal at the own inherent bit position in the transmission frame when the master address or the slave address coincides with the contents of the own group address data. Since it is possible to transmit the transmission data among a number of grouped units with one transmission frame, the data from a number of data collecting units connected to the bus can be transferred to the data processing unit speedily thereby enabling the system to operate at a high speed.

Claims

1. A CSMA type communication system for transmitting digital data among a data processing unit and a number of groups of data collecting units connected to a bus, said data collecting units each comprising:

a means for storing an own inherent address data, a group address data common to said data collecting units in the same group and a data-bit position data inherently allotted to each of said data collecting units in the same group;

an address comparing means for comparing an address in a transmission frame on said bus with said group address data;

a bit position comparing means for counting a synchronizing signal at a data portion in said transmission frame and comparing said synchronizing signal with said data-bit position data; and

a data transmission means for transmitting data synchronously with said synchronizing signal at the own data-bit position in said transmission frame when the address in said transmission frame coincides with the content of the own group address data.

2. A CSMA type communication system for transmitting digital data among a data processing unit and a number of groups of data collecting units connected to a bus, said data collecting units having respective data input devices, said data collecting units each comprising:

a line receiver and a line driver connected to said bus;

an inherent address storage for storing an own inherent address data;

a data-bit position storage for storing a data-bit position data inherently allotted to each of said data collecting units in the same group;

an address field detector for receiving data from said bus through said line receiver and detecting an address field;

an address comparator for comparing outputs from said address field detector and said own inherent address data;

a CSMA receiver and a synchronous signal counter for counting synchronous signals received through said line receiver;

a data-bit position comparator for comparing outputs from said synchronous signal counter and said data-bit position storage;

a data transmitter for transmitting data to the bus through said line driver based on the outputs from said CSMA receiver, said address comparator and said data-bit positon comparator; and

a data collector for collecting data from a corresponding data input device and controlling said data transmitter.

3. A CSMA type communication system according to claim 2, wherein said data input devices comprise key switches.

4. A CSMA type communication system according to claim 3, which includes a data processing unit, an output unit and a plurality of said data collecting units all connected to said bus, said data processing unit being for receiving and outputting a transmission frame from and to any of said data collecting units and communicating with said output unit after analyzing key-switch data.

5. A CSMA type communication system according to claim 2, which includes a data processing unit and a plurality of output units combined with said data collecting units thereby forming a plurality of data collecting and outputting units, said data collecting and outputting units belonging to the same group being interconnected through said bus, wherein said data input devices are a sensor and each of said data collecting and outputting units further has an indicator connected thereto, whereby an output of a sensor is forwarded to said data processing unit through said bus after being inputted to the data collecting and outputting unit to which said sensor is connected and a resulting data after being processed at said data processing unit is returned to said data collecting and outputting unit and is outputted to an indicator connected to said data collecting and outputting unit.

6. A CSMA type communication system adapted to transfer data between or among a first unit and a plurality of second units all coupled to a common bus, each of said second units comprising:

a means for storing a group address data allotted to a group;

a means for detecting an address data in a transmission frame on said bus and generating a coincident signal when said address data coincides with said group address data;

a means for storing a bit position data indicating a bit position of the data to be outputted to said bus or of the data to be received from said bus;

a means for counting a synchronizing signal at a data portion in said transmission frame;

a means for generating a detecting signal when the data is to be outputted or is to be received based on a synchronous pulse and said bit position data; and

a means for outputting the data to said bus or taking-in the data from said bus based on the generated detection signal during the period in which said coincident signal is being produced.