Information Technology Reference
In-Depth Information
20.4.7
Discuss how WorldFIP uses bus arbitrating tables.
20.5 Notes from the author
WorldFIP is an excellent example of a well-designed bus that is simple to set up and use. It
uses many of the techniques developed in computer networks, such as the use of Manchester
coding and collision detection. It is also based on a layer approach, such as having a
physical layer, a data link layer, a management layer, and so on. This fits in well with the
OSI seven-layered model that is used in computer networks (see Chapter 25), and allows
manufacturers of different systems to interconnect their equipment through standard
interfaces. It also allows software and hardware to integrate well and be portable on
differing systems.
The layered approach also allows for different implementations on each layer. In its
current form it supports bitrates of 31.5 kbps, 1 Mbps, 2.5 Mbps and 5 Mbps, over copper and
fibre optic cables. The polling of data on a WorldFIP network is also extremely flexible
where messages can either be sent periodically or aperiodically.
Another great advantage of WorldFIP is that each parameter on the network can be
assigned a unique ID (a tag). As it is a 16-bit field, up to 65,636 of these tags can be used.
The addressing of the devices is also powerful, and over 1 million addressable devices is
possible (24-bit address).
