Detailed Explanation of the FTE Network in Honeywell DCS Systems

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FTE (Fault Tolerant Ethernet) is a fault-tolerant Ethernet network that forms part of Honeywell’s process control systems; it serves to connect the control components with the monitoring and management components, and it is a very important network within process control systems. The hardware components of a network: switches, network cables, and network cards. Note: The switches are a pair from Cisco; the network cables (cable ends) come in two colors, yellow and green. The network cards (either integrated or installed in each node) are either dual-port or consist of two single-port network cards. Each node in the FTE network has two network ports, connected by two cables of different colors: a yellow cable is used to connect one port to one of the switches, while a green cable is used to connect the other port to another switch. (As shown in the figure below), there is a trunk link connecting the two switches, which is used to facilitate data transmission between them (information related to trunk links can be found on Baidu). This type of network structure has two advantages: 1. Any two nodes can be connected through four paths (A-A, B-B, A-B, B-A; one can draw these on paper). 2. Multiple-point fault tolerance: with four paths available, even if one, two, or three of them are damaged, communication between the two nodes can still be maintained. Software composition (Honeywell’s patented FTE software): The FTE software is included in Honeywell’s software packages, and it is selected for installation by default during the software installation process on each node (server, workstation). Other Honeywell nodes in the network (C300 controllers, SM controllers, etc.) have the corresponding software functions embedded in their hardware; hardware from other manufacturers, or computers that do not have the FTE software installed, do not possess FTE network capabilities and are therefore considered non-FTE nodes. Equipped with (encapsulated) FTE software, a true FTE node possesses the following two functions: 1. Fast communication speed. Since there are four communication paths—A-A, B-B, A-B, and B-A—between any two nodes in the FTE network, this software sends out monitoring signals on a millisecond scale during communication to determine which of these four paths offers the fastest speed and best quality; once that path is identified, communication takes place via it. This monitoring continues, meaning that although there are four physical redundant paths, communication actually occurs over the best one. 2. The switching time is short; if it is determined during the communication process that the path being used is not the best, for example, if communication was originally taking place via route A-A, and continuous signal monitoring reveals that A-A is not the optimal path, the network will switch to the path with the best quality at that time, such as A-B. As shown in the diagram, the connection switches from the red-colored path to the green-colored path, with the common portion of both paths remaining unchanged while only certain parts of the network are switched, which results in a fast switching speed.