US 6,891,850 B1Granted

Network independent safety protocol for industrial controller

AssigneeRockwell Automation Technologies, Inc.

InventorsKerry W. Vandesteeg, David A. Vasko, Joseph A. Lenner, Kenwood H. Hall

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Abstract

A highly reliable industrial control system is produced using a network running a standard serial protocol. A safety protocol is embedded within the standard serial protocol by adding to special error detecting data redundant with the protocol of the standard serial network. In addition an overarching protocol involving timing of messages is imposed to provide the necessary level of reliability in the standard serial network. This approach allows the safety protocol to be used with a wide variety of commercially available serial communication standards without modification of the media or the specialized integrated circuits used for that communication. Safety protocol may be implemented in an additional level for integrated circuits or through firmware changes in programmable aspects of the industrial controller components.

Claims17

Dependent claims

A network-independent, high-reliability communications system for an industrial controller using a standard serial communications network, the communications system comprising:

a first I/O communications circuit receiving I/O data for control of an industrial process;
a first network-independent protocol device receiving the I/O data and formatting it for transmission under a network-independent protocol to produce high-reliability formatted data formatted to reduce undetected transmission loop errors, the formatting including at least one of a cyclic redundancy code related to the I/O data and a sequence count related to the local order of transmission of the I/O data with respect to other I/O data being transmitted;
a first standard network protocol device receiving the high-reliability formatted data and further formatting it for transmission under a protocol of the standard serial communications network, to produce doubly-formatted data for transmission on the standard serial communications network, the protocol of the standard serial communications network also formatting data to reduce undetected transmission loop errors, the formatting including at least one of a cyclic redundancy code related to the I/O data and a sequence count related to the local order of transmission of the I/O data with respect to other I/O data being transmitted, the cyclic redundancy code and sequence count being redundant with the cyclic redundancy code and sequence count of the first network independent protocol device;
a second standard network-protocol device receiving the doubly-formatted data from the standard serial communications network and extracting the high-reliability formatted data according to the protocol of the standard serial communications network;
a second network-independent protocol device receiving the high-reliability formatted data and extracting the I/O data;
and
a second I/O communications circuit receiving I/O data for control of an industrial process from the second network-independent protocol device;
whereby high-reliability transmissions may be simply obtained on an arbitrary standard serial communications network protocol.

5 more elements

A method of providing a high-reliability communications system for an industrial controller using a standard serial communications network, the communications system comprising the steps of:

(a) receiving I/O data for control of an industrial process at a first I/O communications circuit;
(b) formatting the received I/O data for transmission under a network-independent protocol at a first standard network protocol device to produce high-reliability formatted data formatted to reduce undetected transmission loop errors, the formatting including at least one of a cyclic redundancy code related to the I/O data and a sequence count related to the local order of transmission of the I/O data with respect to other I/O data being transmitted;
(c) receiving the high-reliability formatted data at a first standard network protocol device and further formatting it for transmission under a protocol of the standard serial communications network, to produce doubly-formatted data for transmission on the standard also formatting data to reduce transmission loop errors, the formatting including at least one of a cyclic redundancy code related to the I/O data and a sequence count related to the local order of transmission of the I/O data with respect to other I/O data being transmitted, the cyclic redundancy code and sequence count being redundant with the cyclic redundancy code and sequence count of the first network independent protocol device;
(d) receiving the doubly-formatted data from the standard serial communications network at a second standard network-protocol device and extracting the high-reliability formatted data according to the protocol of the standard serial communications network;
(e) receiving the high-reliability formatted data at a second network-independent protocol device and extracting the I/O data;
and
(f) receiving I/O data for control of an industrial process from the second network-independent protocol device at a second I/O communications circuit;
whereby high-reliability transmissions may be simply obtained on an arbitrary standard serial communications network protocol.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/663,824Filed 18 Sep 2000 · us provisional application
Priority: 22 Dec 1999
Granted: 10 May 2005
Term ends: Not estimatedThe source records don’t support an estimate.

Classification13 codes

H04L 43/50
Arrangements for monitoring or testing data switching networks: testing arrangements
G05B 19/0423
Using digital processors: input/output
G05B 19/0425
Input/output: safety, monitoring
G05B 19/4185
Total factory control, i.e. centrally controlling a plurality of machines, e.g. direct or distributed numerical control [DNC], flexible…:…