SAFETY NETWORK FOR INDUSTRIAL CONTROLLER HAVING REDUCED BANDWIDTH REQUIREMENTS

摘要

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. The system may also use a standard network for configuration by symmetrically transmitting configuration data to intercommunicating controller components. The configuration data provides a unique identification to each component to reduce the possibility of misdirected messages and provides the protocols to be used by the components reducing the chance of garbled messages. Two connections may be used to transmit redundant data and include a reply message to the message producer. Comparison of the data of the two messages can reveal other types of failure not apparent by these former techniques. The system provides for the processing of redundant control signals on as little as a single serial network without overloading the network by preprocessing input signals for coincidence and sending only the coincidence signal either periodically or on a change of state.