Chapter 15: Appendix
[7] Principles of the FL-net system
The goal of an FL-net is real-time communication between controllers, such as programmable control- lers, robot controllers, and numeric control devices, in production systems.
The FL-net constructs a token passing mechanism using an instantaneous information transfer based on Ethernet UDP/IP protocols to execute cyclic and message communications.
[8] Differences between a general-purpose Ethernet and FL-net
FL-net is a network developed specifically for the FA (Factory Automation) field. Therefore, not all general purpose Ethernet equipment can be used on the FL-net. Some items may not have suitable noise immunity in an electrically noisy environment.
FL-net is must respond immediately, to maintain real-time communication for control, and therefore only controllers and control equipment compatible with the FL-net can be connected.
FL-net employs a cyclic communication method, using the instantaneous information transfer function of UDP/IP communication on 10BASE5/10BASE-T systems. Therefore, it has the following limi- tations.
1.The devices currently available are only compatible with a 10Mbps Ethernet LAN.
2.Cannot have other general-purpose Ethernet devices connected to the network.
3.Does not support the TCP/IP communication function.
4.The use of a switching hub is not supported.
5.When a router is used, some router functions cannot be used.
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