摘要:
The subject matter disclosed herein describes a method to allocate and prioritize data communications on an industrial control network. A transmission schedule (28) including multiple priority windows and multiple queues (Q) is established. Each queue (Q) is assigned to at least one priority window, and each priority window may have multiple queues (Q) assigned thereto. A control device (10) communicating on the control network (12) transmits data packets according to the transmission schedule (28). Within each priority window, data packets corresponding to one of the queues (Q) assigned to the priority window may be transmitted. The data packets may be transmitted at any point during the priority window, but will only be transmitted if no data packet from a higher queue (Q) is waiting to be transmitted.
摘要:
Fault-tolerant Ethernet is provided through the use of special interfaces (14a,b) providing duplicate ports that may be alternatively enabled with the same network address. A switching between the ports, corrects for single faults in a two-way redundant system (16a,b) without time-consuming reconfiguration of other end devices (12a-e) or the need for complex middleware in the end devices (12a-e).
摘要:
A system and method for precisely synchronizing clocks in separate nodes (10, 11, 12, 13) on a communication network (15) is provided by adjusting timestamps and related data in network messages. A circuit (10a, 11a, 12a, 13a) will allow a daisy-chain connection of the nodes (10, 11, 12, 13) and will forward time synchronization frames while accounting for delays in a manner that does not use boundary clocks, but does not depart from the IEEE 1588 standard protocol. The delays will be added on the fly to synchronization packets and the IP checksum and frame CRC will be adjusted. Deterministic data delivery and redundant data paths are also provided in a full duplex Ethernet network.
摘要:
Multiple gateway devices communicating between a device level ring (DLR) network and a spanning tree (ST) network may be provided a gateway protocol that cooperatively ensures that only a single gateway is active at a given time. This cooperation may be effected by the transmission of advertise messages by gateways, the advertise messages holding precedence values so that only a single gateway having a highest precedence value is active at a given time. Loss of the advertise messages may trigger a gateway held in a backup state to assume an active gateway role.
摘要:
Fault-tolerant Ethernet is provided through the use of special interfaces providing end-devices with duplicate ports that may be alternatively enabled with the same network address in the event of a fault detected by loss of the message from a beacon device. Unidirectional network errors in the direction from the end-device to the beacon devices are detected through a path check message from the end-device to the beacon device. Multiple faults may be accommodated without network interruption by adding top-level switches without increasing the number of ports on the end-devices by cross connecting a lowest level of switch.
摘要:
The subject matter disclosed herein describes a method to allocate and prioritize data communications on an industrial control network. A transmission schedule (28) including multiple priority windows and multiple queues (Q) is established. Each queue (Q) is assigned to at least one priority window, and each priority window may have multiple queues (Q) assigned thereto. A control device (10) communicating on the control network (12) transmits data packets according to the transmission schedule (28). Within each priority window, data packets corresponding to one of the queues (Q) assigned to the priority window may be transmitted. The data packets may be transmitted at any point during the priority window, but will only be transmitted if no data packet from a higher queue (Q) is waiting to be transmitted.