Communication system and slave and repeater units therefor

• US 7,792,155 B2
• Filed: 08/30/2006
• Issued: 09/07/2010
• Est. Priority Date: 08/31/2005
• Status: Active Grant

• Current Assignee: Omron Corporation
• Original Assignee: Omron Corporation
• Inventors: Ozaki, Toshiyuki, Fujikawa, Masanori, Koga, Masao
• Primary Examiner(s): Mattis; Jason E
• Assistant Examiner(s): BEDNASH, JOSEPH A
• Application Number:
  US11/513,640
• Publication Number:
  US 20070047588A1
• Time in Patent Office: 1,469 Days
• Field of Search: 370/257, 370/389, 370/390, 370/392, 370/395.1, 370/395.31, 370/395.4, 370/395.7, 370/401, 370/402, 370/408, 370/410, 370/414, 370/443
• US Class Current: 370/508
• CPC Class Codes: G05B 19/41855 by local area network [LAN], network structure
• CPC Class Codes: G05B 2219/31127 Repeater between two networks
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]

Abstract

A communication system is formed with a master unit having a communication function and at least one slave unit also having a communication function connected by a network including a bus. Repeater units are inserted on the network between the master unit and the slave unit in one or more stages. As the master unit transmits request frames downstream through the network to the slave unit, the slave unit control the timing of transmitting the response frames in response successively such that the master unit receives the response frames without waiting in between regardless of repeater delay times of each of the returned response frames determined by the number of stages of the repeater units. Each communication frame that is transmitted through the network contains identification data indicative of its type and each repeater unit serves to repeat certain types of received frames only in the upstream direction.

Claims

1. A communication system comprising:

a master unit which is a programmable controller having a communication function;

at least one slave unit which is an I/O terminal unit having a communication function and connected to said master unit by a network; and

repeater units inserted on said network between said master unit on their upper side and said at least one slave unit in one or more stages on their lower side;

wherein communication frames of various types are transmitted through said network, each of said communication frames containing identification data indicative of the type thereof;

wherein a type of a communication frame to be transmitted from said slave unit to said master unit contains identification data indicative of such the type of frame;

wherein said repeater units include an upper port connected to the upstream side of said network and a lower port connected to the downstream side of said network, and serve to repeat said communication frame only in a direction from said lower port to said upper port when it is determined that said communication frame received by said repeater units through said upper port or said lower port contains the identification data indicative of the type of frame to be transmitted from said slave unit to said master unit;

wherein said master unit serves to transmit a specific communication frame of said communication frames of various types and read out, from one of response frames received from said slave unit in response to said specific communication frame transmitted from said master unit, the number of stages of repeater units passed by the received response frames, to write information into said slave unit for setting a timing for returning the response frames from the slave unit to said master unit based on said number that has been read out;

wherein said timing is set for each slave unit to return response frames in response to a communication frame from said master unit such that said master unit receives said returned response frames with no space between said returned response frames regardless of repeater delay times of each of said returned response frames.

2. The communication system of claim 1, wherein a type of a communication frame to be transmitted from said master unit to said slave unit contains identification data indicative of such type of frame;

and

wherein said repeater units repeat said communication frame only in a direction from said upper port to said lower port when it is determined that said communication frame received by said repeater units through said upper port or said lower port contains the identification data indicative of the type of frame to be transmitted from said master unit to said slave unit.

3. The communication system of claim 2, wherein a type of a communication frame to be transmitted in both directions between said master unit and said slave unit contains identification data indicative of such type of frame;

and

wherein said repeater units repeat said communication frame in a direction from said upper port to said lower port when it is determined that said communication frame received by said repeater units through said upper port contains the identification data indicative of the type of frame to be transmitted in both direction between said master unit and said slave unit, and

said repeater units repeat said communication frame in a direction from said lower port to said upper port when it is determined that said communication frame received by said repeater units through said lower port contains the identification data indicative of the type of frame to be transmitted in both direction between said master unit and said slave unit.

4. The communication system of of claim 3,

wherein said slave unit stores the number of stages of said repeater units between said slave unit and said master unit.

5. The communication system of claim 4, wherein a type of a communication frame to be transmitted from said master unit to said slave unit contains identification data indicative of such type of frame;

and

wherein said repeater units repeat said communication frame only in a direction from said upper port to said lower port when it is determined that said communication frame received by said repeater units through said upper port or said lower port contains the identification data indicative of the type of frame to be transmitted from said master unit to said slave unit.

6. The communication system of of claim 2,

wherein said slave unit stores the number of stages of said repeater units between said slave unit and said master unit.

7. The communication system of claim 6, wherein a type of a communication frame to be transmitted from said master unit to said slave unit contains identification data indicative of such type of frame;

and

wherein said repeater units repeat said communication frame only in a direction from said upper port to said lower port when it is determined that said communication frame received by said repeater units through said upper port or said lower port contains the identification data indicative of the type of frame to be transmitted from said master unit to said slave unit.

8. The communication system of claim 1, wherein a type of a communication frame to be transmitted in both directions between said master unit and said slave unit contains identification data indicative of such type of frame;

and

wherein said repeater units repeat said communication frame in a direction from said upper port to said lower port when it is determined that said communication frame received by said repeater units through said upper port contains the identification data indicative of the type of frame to be transmitted in both direction between said master unit and said slave unit, and

said repeater units repeat said communication frame in a direction from said lower port to said upper port when it is determined that said communication frame received by said repeater units through said lower port contains the identification data indicative of the type of frame to be transmitted in both direction between said master unit and said slave unit.

9. The communication system of of claim 8,

wherein said slave unit stores the number of stages of said repeater units between said slave unit and said master unit.

10. The communication system of claim 9, wherein a type of a communication frame to be transmitted from said master unit to said slave unit contains identification data indicative of such type of frame;

and

wherein said repeater units repeat said communication frame only in a direction from said upper port to said lower port when it is determined that said communication frame received by said repeater units through said upper port or said lower port contains the identification data indicative of the type of frame to be transmitted from said master unit to said slave unit.

11. The communication system of claim 1, wherein said specific communication frame is adapted to contain data on address values of the repeater units that have been passed and data on the number of stages of the repeater units;

wherein said repeater units serve to cause said specific communication frames to contain data on the address value of said repeater unit and the value of one plus the number of stages of the repeater units when one of said specific communication frames passes through said repeater unit; and

wherein said slave unit serves to read out of said specific communication frame data on the address value of the repeater unit adjoining in the upstream direction and on the number of repeater units to cause said response frame to said master unit to contain data on the address value of the repeater unit adjoining in the upstream direction and the number of stages of the repeater units read out of said specific communication frame.

12. The communication system of claim 1 wherein said communication frames of various types include an “

In-frame”

for transmitting input data of said I/O terminal unit by said slave unit;

wherein the slave unit serves to return said In-frame based on said information on timing, faster by the length of repeater delay when said In-frame is sent by said slave unit; and

wherein said repeater units repeat said In-frame only in a direction of from said lower port to said upper port.

13. The communication system of claim 1 wherein said slave unit is adapted to transmit a connection frame for acknowledging existence of said slave unit to said master unit;

wherein said master unit serves to transmit a request frame for requesting said slave unit to transmit said connection frame;

wherein said communication frames include said connection frame and said request frame;

wherein said slave unit serves to return said connection frame based on said information on timing, faster by the length of repeater delay when said connection frame is sent by said slave unit; and

wherein said repeater units repeat said connection frame only in a direction from said lower port to said upper port.

14. The communication system of claim 13, wherein a type of a communication frame to be transmitted in both directions between said master unit and said slave unit contains identification data indicative of such type of frame;

and

wherein said repeater units repeat said communication frame in a direction from said upper port to said lower port when it is determined that said communication frame received by said repeater units through said upper port contains the identification data indicative of the type of frame to be transmitted in both direction between said master unit and said slave unit, and

said repeater units repeat said communication frame in a direction from said lower port to said upper port when it is determined that said communication frame received by said repeater units through said lower port contains the identification data indicative of the type of frame to be transmitted in both direction between said master unit and said slave unit.

15. The communication system of claim 1,

wherein said slave unit stores the number of stages of said repeater units between said slave unit and said master unit.

16. The communication system of claim 15, wherein a type of a communication frame to be transmitted from said master unit to said slave unit contains identification data indicative of such type of frame;

and

wherein said repeater units repeat said communication frame only in a direction from said upper port to said lower port when it is determined that said communication frame received by said repeater units through said upper port or said lower port contains the identification data indicative of the type of frame to be transmitted from said master unit to said slave unit.

17. The communication system of claim 15, wherein a type of a communication frame to be transmitted in both directions between said master unit and said slave unit contains identification data indicative of such type of frame;

and

wherein said repeater units repeat said communication frame in a direction from said upper port to said lower port when it is determined that said communication frame received by said repeater units through said upper port contains the identification data indicative of the type of frame to be transmitted in both direction between said master unit and said slave unit, and

said repeater units repeat said communication frame in a direction from said lower port to said upper port when it is determined that said communication frame received by said repeater units through said lower port contains the identification data indicative of the type of frame to be transmitted in both direction between said master unit and said slave unit.

18. The communication system of claim 15, wherein said master unit serves to transmit a request frame to the slave unit for requesting transmission of a connection frame for acknowledging existence of said slave unit;

wherein said slave unit serves to transmit said connection frame to said master unit based on said timing, faster by the length of repeater delay when said connection frame is sent by said slave unit; and

wherein said repeater units repeat said connection frame only in a direction from said lower port to said upper port.

19. The communication system of claim 15, wherein said communication frames of various types include an “

In-frame”

for transmitting input data of said I/O terminal unit by said slave unit;

wherein the slave unit serves to return “

In-frame”

containing said input data of said I/O terminal such that said master unit receives said response frames with no space between said returned response frames regardless of repeater delay times of each of said returned response frames; and

wherein said repeater units repeat said In-frame only in a direction from said lower port to said upper port.