Serial bus communication method in a refrigeration system

• US 5,323,385 A
• Filed: 01/27/1993
• Issued: 06/21/1994
• Est. Priority Date: 01/27/1993
• Status: Expired due to Fees

• Current Assignee: Westinghouse Electric Corporation (Paramount Global (f/k/a ViacomCBS Inc.))
• Original Assignee: Thermo King Corporation (Trane Technologies plc)
• Inventors: McCormack, Michael D., Jurewicz, Romuald M., Johnson, Dannis R.
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): VU, HUY DUY
• Application Number:
  US08/010,092
• Time in Patent Office: 510 Days
• Field of Search: 370/85.1, 370/43, 370/94.1, 370/99, 370/79, 370/110.1, 370/82, 370/83, 340/825.06, 340/825.07, 340/825.5, 340/825.1, 340/825.52, 340/825.53, 340/825.57, 340/825.62
• US Class Current: 370/300
• CPC Class Codes: H04L 12/40163 by assigning priority to messages according to a message field
• CPC Class Codes: H04L 12/4135 using bit-wise arbitration
• CPC Class Codes: H04L 2012/40215 Controller Area Network CAN
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

A method of communication in a refrigeration system, between communication nodes connected to a serial data bus using Controller Area Network protocol (CAN) having a message frame format which includes a data field. The method includes converting a byte of the data field of each message frame to a permanent data descriptor expansion byte (DEB). In at least the first frame of a message a specific bit of the DEB is set to a first logic level to indicate a control frame, and information descriptive of the whole message is loaded into the remaining bits of the DEB, and data field. In each remaining frame of a message following a control frame, or control frames, the specific bit is set to a second logic level, to indicate a data frame. A block of data is loaded into the data field of each data frame, and index information specific to the associated block of data is loaded into the remaining bits of the DEB.

Claims

1. A method of two-way communication in a refrigeration system between a central communication node and remote nodes via serial data bus using a modified Controller Area Network protocol having a fixed message frame format which includes a combined identification and arbitration field and a data field, comprising the steps of:

converting a predetermined portion of the data field of each message frame to a permanent data descriptor expansion byte (DEB),

setting a predetermined bit of said DEB to a first logic level in at least the first frame of a message, to indicate a control frame,

loading information descriptive of the message in the remaining bits of said DEB, and in the remaining data field, of said control frame,

said message descriptive information in the data field of the control frame including an algorithm and algorithm block number associated with the data being transmitted, when the data is being transmitted from and to the central communication node,

setting said predetermined bit of said DEB to a second logic level in at least one subsequent frame of the message, to indicate a data frame,

loading a block of data in the data field of each data frame,

and loading index information in the remaining bits of the DEB in each data frame which is specific to the data of the associated data frame.

2. A method of two-way communication in a refrigeration system between a central communication node and remote nodes via serial data bus using a modified Controller Area Network protocol having a fixed message frame format which includes a combined identification and arbitration field and a data field, comprising the steps of:

converting a predetermined portion of the data field of each message frame to a permanent data descriptor expansion byte (DEB),

setting a predetermined bit of said DEB to a first logic level in at least the first frame of a message, to indicate a control frame,

loading information descriptive of the message in the remaining bits of said DEB, and in the remaining data field, of said control frame,

said message descriptive information in the data field of the control frame of a message transmitted by a remote node indicating when the message is a request for data to be sent from the central communication node,

setting said predetermined bit of said DEB to a second logic level in at least one subsequent frame of the message, to indicate a data frame,

loading a block of data in the data field of each data frame,

and loading index information in the remaining bits of the DEB in each data frame which is specific to the data of the associated data frame.

3. The method of claim 2 wherein the data field of the data frames of the request-for-data message identifies the information to be sent.

4. A method of two-way communication in a refrigeration system between a central communication node and remote nodes via serial data bus using a modified Controller Area Network protocol having a fixed message frame format which includes a combined identification and arbitration field and a data field, comprising the steps of:

converting a predetermined portion of the data field of each message frame to a permanent data descriptor expansion byte (DEB),

setting a predetermined bit of said DEB to a first logic level in at least the first frame of a message, to indicate a control frame,

loading information descriptive of the message in the remaining bits of said DEB, and in the remaining data field, of said control frame,

said message descriptive information in the data field of the control frame of a message transmitted by a remote node indicating when the message is sending data to be stored at the central communication node,

setting said predetermined bit of said DEB to a second logic level in at least one subsequent frame of the message, to indicate a data frame,

loading a block of data in the data field of each data frame,

and loading index information in the remaining bits of the DEB in each data frame which is specific to the data of the associated data frame.

5. The method of claim 4 wherein the data field of a data frame of the message includes an identification of the data being sent followed by the information.

6. The method of claim 5 wherein the data identification and associated data are in blocks each having a like predetermined number of bytes, with the first byte of each block being a data identifier and with the remaining bytes of each block being the identified data.

7. A method of two-way communication in a refrigeration system between a central communication node and remote nodes, with one of the nodes being a data logger, via serial data bus using a modified Controller Area Network protocol having a fixed message frame format which includes a combined identification and arbitration field and a data field, comprising the steps of:

converting a predetermined portion of the data field of each message frame to a permanent data descriptor expansion byte (DEB),

setting a predetermined bit of said DEB to a first logic level in at least the first frame of a message, to indicate a control frame,

loading information descriptive of the message in the remaining bits of said DEB, and in the remaining data field, of said control frame,

said message descriptive information in the data field of the control frame of a message transmitted by a remote node indicating when the message is a request for a data logger transmission,

setting said predetermined bit of said DEB to a second logic level in at least one subsequent frame of the message, to indicate a data frame,

loading a block of data in the data field of each data frame,

and loading index information in the remaining bits of the DEB in each data frame which is specific to the data of the associated data frame.

8. The method of claim 7 wherein the data field of the data frames of the message include a message to be stored at the central node, and including the step of storing the message at the central node along with an identification of the remote node which sent the message.