Safety Modbus Protocol

• US 20050149631A1
• Filed: 01/07/2004
• Published: 07/07/2005
• Est. Priority Date: 01/07/2004
• Status: Abandoned Application

• Current Assignee: Schneider Automation Incorporated (Schneider Electric SE)
• Original Assignee: Schneider Automation Incorporated (Schneider Electric SE)
• Inventors: Decker, Bruce Michael
• Application Number:
  US10/707,721
• Publication Number:
  US 20050149631A1
• Time in Patent Office: Days
• US Class Current: 709/230
• CPC Class Codes: H04L 1/0061 Error detection codes
• CPC Class Codes: H04L 2001/0094 Bus
• CPC Class Codes: H04L 69/16 Implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP]
• CPC Class Codes: H04L 69/28 Timers or timing mechanisms used in protocols

Abstract

A protocol for communication between automation devices and a method for communicating between automation devices is disclosed. The protocol is an enhancement to the Modbus/TCP protocol, and includes a CRC-32 and time stamp fields at the application layer to increase the assurance of the message integrity. This increased integrity in network messages is critical in the operation of safety system.

Claims

1. A communications network between automation devices consisting:

an automation device capable of communicating using a TCP and an IP messaging technique,

whereby the messaging technique consists of sending a message to reserved TCP/IP system port 502,

and whereby said applications layer message includes a cyclic redundancy check field.

2. The communication network between automation devices of claim 1 whereby the cyclic redundancy check field is calculated using a CRC-32 algorithm.

3. The communication network between automation devices of claim 1 whereby the applications layer message further includes a time stamp representing the time that the message was sent.

4. The communication network between automation devices of claim 3 whereby the applications layer message further includes a time stamp qualifier.

5. A method of communicating between automation devices comprising

formulating an applications layer message that includes a cyclic redundancy check;

transmitting said message over an Ethernet network using a TCP/IP stack, whereby said message is sent to TCP/IP system port 502.

6. The method of communicating between automation devices in claim 5 whereby the cyclic redundancy check is calculated using a CRC-32 algorithm.

7. The method of communicating between automation devices in claim 5 further comprising the step of determining a time stamp and including said time stamp in the applications layer message.

8. The method of communicating between automation devices in claim 7 whereby the applications layer message further includes a time stamp qualifier.