Abstract: A high reliability network provides for measurements of network delays through pairs of transmissions of local clock values used in a first message to deduce clock value offsets and in a second message to reveal network delays.

Abstract: A safety controller with redundant controllers, each executing safety tasks and comparing their results, provides an improved interface in which a user interacts with a single processor and the second processor is invisible. The interacting processor provides for the transmission of programs and variables to both processors when they are safety tasks and coordinates synchronization of the two programs and comparison of their operation all without additional user input.

Abstract: A safety controller executes a control program in two processing units to detect processor failure by comparison of the execution in each unit. This comparison is made rapid by synchronizing the input variables at the beginning of the task and comparing output variables at a conclusion of the task, avoiding line-by-line comparison of input and output variables. Intermediate variables, that are neither input nor output values, are compared at a less frequent interval.

Abstract: Messages in a high reliability industrial control system are associated with safety messages that enable reliable detection of data errors caused during transmission of the message over the network. In particular, error detection codes are generated and transmitted along with message data. At a receiving node, an expected EDC is generated and compared to the EDC transmitted over the network to determine whether any data was corrupted.

Abstract: A safety controller having a total worst case propagation delay, exceeding the required propagation delay required by a safety process, may be used to control the safety process by monitoring actual delays in signal processing in the safety controller and moving to a safety state if a signal delay exceeds an amount less than the total worst case propagation delay.

Abstract: Messages in a high reliability industrial control system are associated with safety addresses preventing errors caused by misdirected messages. The safety address, however, is not transmitted with the message, but instead only the data of the message and an error detecting code based on a combination of the data and the safety address is sent. At a receiving node, an expected safety address is concatenated to the data of the message and the transmitted error correcting code compared against this combination to confirm proper addressing of the message. Network capacity is thus improved.

Abstract: Messages in a high reliability industrial control system are associated with safety addresses preventing errors caused by misdirected messages. The safety address, however, is not transmitted with the message, but instead only the data of the message and an error detecting code based on a combination of the data and the safety address is sent. At a receiving node, an expected safety address is concatenated to the data of the message and the transmitted error correcting code compared against this combination to confirm proper addressing of the message. Network capacity is thus improved.

Abstract: A high reliability network provides for measurements of network delays through pairs of transmissions of local clock values used in a first message to deduce clock value offsets and in a second message to reveal network delays.