Method and apparatus for saving and performing industrial control commands

• US 4,942,552 A
• Filed: 11/20/1986
• Issued: 07/17/1990
• Est. Priority Date: 11/20/1986
• Status: Expired due to Term

• Current Assignee: Allen-Bradley Company (Rockwell Automation, Inc.)
• Original Assignee: Allen-Bradley Company (Rockwell Automation, Inc.)
• Inventors: Strader, Robert C., Merrill, Richard A., Crockett, Bruce L.
• Primary Examiner(s): Zache, Raulfe B.
• Assistant Examiner(s): Chan, Emily Y.
• Application Number:
  US06/932,987
• Time in Patent Office: 1,335 Days
• Field of Search: 364/200 MS File, 364/900 MS File
• US Class Current: 710/6
• CPC Class Codes: G05B 19/052 Linking several PLC's
• CPC Class Codes: G05B 19/4181 characterised by direct numerical control [DNC]
• CPC Class Codes: G08C 15/00 Arrangements characterised by the use of multiplexing for the transmission of a plurality of signals over a common path
• CPC Class Codes: H04Q 9/14 Calling by using pulses
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]

Abstract

A communications system for industrial controllers includes interface controllers which implement a remote command capability. The remote command feature allows conventional communications commands to be saved at a responding interface controller in a remote command table and performed at a later time. A "SAVE" type remote command includes an ID field and an embedded command. The embedded command is stored in the remote command table at a location corresponding to the ID field. The ID field is used to access the embedded command in subsequent remote commands. A "PERFORM" type remote command contains a string of ID'"'"'s, which indicates which saved commands are to be performed and the order in which to perform them. When a PERFORM command is received, the conventional command stored in the remote command table is recalled and transmitted onto a communications network. The PERFORM command can be addressed to a single interface controller, or it can be broadcast to all interface controllers in the communications system. Remote commands are also provided to examine and delete remote command table entries at a responding interface controller.

Claims

1. A method for processing communications command messages in an interface controller which forms part of a network station, the interface controller being connected to a communications network interconnecting a plurality of network stations, and in which each command message is a member of a predetermined set of command messages, the method comprising the steps of:

(a) receiving a first command message in the interface controller from the communications network, the first command message being a SAVE type remote command message which was originated by one of said plurality of network stations, the first command message including an embedded command and a first ID field comprising a unique identifier corresponding to the embedded command, the embedded command comprising at least a first destination field which identifies one or more of said plurality of network stations and a first operation code which identifies one command message from said predetermined set of command messages, the embedded command being embedded in the format of the first command message;

(b) storing the embedded command in a remote command table which forms a part of said interface controller at a location in the remote command table corresponding to the unique identifier in the first ID field;

(c) repeating steps (a) and (b) to receive and store a plurality of embedded commands in the remote command table, each embedded command being stored in the remote command table at a location corresponding to the unique identifier in the ID field;

(d) receiving a second command message in the interface controller from the communications network, the second command message being a PERFORM type remote command message which was originated from one of said plurality of network stations and the second command message including one or more second ID fields, each second ID field including the unique identifier corresponding to one of said plurality of embedded commands; and

(e) responding to the second command message by the interface controller by (i) retrieving the embedded command corresponding to the unique identifier in one of the second ID fields from the remote command table, (ii) forming a third command message by including a second destination field in the third command message which comprises the first destination field from the retrieved embedded command and by including a second operation code in the third command message which comprises the first command code from the retrieved embedded command, (iii) transmitting the third command message onto the communications network to one or more target network stations as designated by the second destination field, and (iv) performing steps (i) through (iii) for each embedded command corresponding to the unique identifier in each second ID field.

2. The method of claim 1 in which said one or more target network stations includes the same network station that originated the second command message in step (d).

3. The method of claim 1 in which said one or more target network stations excludes the network station that originated the second command message in step (d).

4. The method of claims 1, 2 or 3 further comprising the steps of:

(f) receiving in the interface controller at least one first status replay message from the communication network, each first status reply message including a status code response and originating from one of the target network stations in response to one of the third command messages transmitted in step (e) (iii); and

(g) transmitting from the interface controller a second status reply message onto the communication network, the second status reply message being addressed to the network station from which the second command message was received in step (d), said second status reply message including the status code response of each of said at least one first status reply messages received.

5. The method of claims 1, 2 or 3 in which at least a portion of the remote command table resides in a nonvolatile memory and at least one of the embedded commands is stored in the nonvolatile memory portion of the remote command table.

6. The method of claims 1, 2 or 3 further comprising the steps of:

(f) receiving in the interface controller a fourth command message from the communication network at a time after performing at least one iteration of step (b), the fourth command message being an EXAMINE type remote command message which was originated by one of said plurality of network stations, the fourth command message including an examine code which specifies the unique identifier corresponding to one of said plurality of embedded commands stored in the remote command table; and

(g) transmitting from the interface controller a reply message onto the communications network, the reply message being addressed to the network station which originated the fourth command message, and the reply message including a copy of the embedded command from the remote command table corresponding to the examine code in the fourth command message.

7. The method of claims 1, 2 or 3 further comprising the steps of:

(f) receiving in the interface controller a fourth command message from the communications network at a time after performing at least one iteration of step (b), the fourth command message being a DELETE type remote command message which was originated by one of said plurality of network stations, the fourth command message including a delete code which specifies the unique identifier corresponding to one of said plurality of embedded commands stored in the remote command table;

(g) deleting the embedded command specified by the delete code from the remote command table in the interface controller; and

(h) transmitting from the interface controller a reply message onto the communications network, the reply message being addressed to the network station which originated the fourth command message, and the reply message including a status code indicating that the embedded command specified by the delete code has been deleted from the remote command table.

8. A method for saving a communications command message and subsequently performing the communications command message in a plurality of stations interconnected by a communications network comprising the steps of:

(a) transmitting a first command message from a first one of said plurality of stations to a first responder station, the first command message being a SAVE type remote command message which includes an embedded command, the embedded command comprising at least a destination field which identifies one or more of said plurality of network stations and an operation code which identifies one command message from said predetermined set of command messages, the embedded command being embedded in the format of the first command message;

(b) receiving the first command message at the first responder station;

(c) extracting the embedded command at the first responder station and storing the embedded command in a remote command table which forms a part of the first responder station;

(d) repeating steps (a), (b) and (c) to transmit, extract and store another embedded command in the remote command table of a second responder station, thereby storing embedded commands in at least two different responder stations;

(e) transmitting a second command message from a second one of said plurality of stations as a single broadcast message to said at least two different responder stations, the second command message being a PERFORM type remote command message;

(f) receiving the second command message at each of said at least two different responder stations and responding to the second command message at each of said at least two different responder stations by (i) recalling the embedded command from the remote command table, (ii) forming a third command message by including a second destination field in the third command message which comprises the first destination field from the embedded command and by including a second operation code in the third command message which comprises the first command code from the embedded command, and (iii) transmitting the third command message to one or more target network stations as designated by the second destination field.

9. An Interface Controller connected to a communications network for implementing a predetermined set of command messages comprising:

network I/O means for transmitting and receiving messages over the communications network; and

processor means connected to the network I/O means for processing data exchanged with the network I/O means, the processor means including;

memory means for storing a remote command table;

command sender means for sending command messages to the network I/O means for transmission over the communications network; and

remote command responder means for processing remote command messages received from the network I/O means, each remote command message being a member of a predetermined set of remote command messages including at least first and second remote command message types, in which the first remote command message type includes an embedded command and a first ID field, the first ID field comprising a unique identifier corresponding to the embedded command, and the embedded command comprising at least a first destination field which identifies one or more of said plurality of network stations and a first operation code which identifies one command message from said predetermined set of command messages, and in which the second remote command type includes a second ID field which includes the unique identifier corresponding to the embedded command, the remote command responder means including;

save means for processing field remote command message types by (a) extracting the embedded command from the first type remote command message and (b) storing the embedded command in the remote command table at a location corresponding to the first ID field; and

perform means for processing the second remote command message type by (c) retrieving the embedded command from the location in the remote command table corresponding to the second ID field, (d) forming an outgoing command message based on the embedded command by including a second destination field in the outgoing command message which comprises the first destination field from the embedded command and by including a second operation code in the outgoing command message which comprises the first command code from the embedded command, and (e) routing the outgoing command message to the command sender means for transmission to one or more target network stations as designated by the second destination field.

10. The interface controller as recited in claim 9 in which the command sender means includes means for receiving a status reply message from the station to which the outgoing command message was sent, the status reply message including a status code response, and in which the perform means includes reply means for receiving the status code response from the command sender means, the reply means including means for routing a remote command reply message to the network I/O means for transmission to a network station from which the second type remote command message was received, the remote command reply message including the status code response.

11. The interface controller as recited in claim 9 in which the memory means includes a nonvolatile memory and at least a portion of the remote command table resides in the nonvolatile memory, and in which at least one embedded command is stored in the portion of the remote command table residing in the nonvolatile memory.

12. The interface controller as recited in claims 9 or 10 in which the predetermined set of remote command messages includes a third remote command message type, the third remote command message type including a third ID field which includes the unique identifier associated with the embedded command stored in the remote command table, and in which the remote command responder means includes examine means for processing the third remote command message type by routing a reply message to the network I/O means for transmission to a network station from which the third type remote command message was received, the reply message including a copy of the embedded command stored in the remote command table at the location indicated by the third ID field.

13. The interface controller as recited in claims 9 or 10 in which the predetermined set of remote command messages includes a third remote command message type, the third remote command message type including a third ID field which includes the unique identifier corresponding to the embedded command stored in the remote command table, and in which the remote command responder means includes delete means for processing the third remote command message type by deleting the embedded command stored in the remote command table at the location indicated by the third ID field.

14. An Interface Controller connected to a communications network for implementing a predetermined set of command messages comprising:

network I/O means for transmitting and receiving messages over the communications network; and

processor means connected to the network I/O means for processing data exchanged with the network I/O means, the processor means including;

memory means for storing a remote command table;

command sender means for sending command messages to the network I/O means for transmission over the communications network, the command sender means including means for receiving a status reply message in response to each command message sent by the command sender means, the status reply message including a status code response; and

remote command responder means for processing remote command messages received from the network I/O means, each remote command message being a member of a predetermined set of remote command messages including at least a first remote command message types, in which the first remote command message type includes an embedded command comprising at least a first destination field which identifies one or more of said plurality of network stations and a first operation code which identifies one command message from said predetermined set of command messages, the remote command responder means including;

perform means for processing first remote command message types by (a) extracting the embedded command from the first remote command message type, (b) forming an outgoing command message by including a second destination field in the outgoing command message which comprises the first destination field from the embedded command and by including a second operation code in the outgoing command message which comprises the first command code from the embedded command, (c) routing the outgoing command message to the command sender means for transmission to one or more target network stations as designated by the second destination field, and (d) receiving the status code response from the command sender means for the outgoing command message sent, and (e) routing a remote command reply message to the network I/O means for transmission to a network station from which the second type remote command message was received, the remote command reply message including the status code response.