Tag: Network Protocols

  • 14.8 Practical considerations – Digital Communication

    A principal consideration for industrial control networks, where the monitoring and control of real-life processes must often occur quickly and at set times, is the guaranteed maximum communication time from one node to another. If you’re controlling the position of a nuclear reactor coolant valve with a digital network, you need to be able to…

  • 14.7 Network Protocols

    Aside from the issues of the physical network (signal types and voltage levels, connector pinouts, cabling, topology, etc.), there needs to be a standardized way in which communication is arbitrated between multiple nodes in a network, even if its as simple as a two-node, point-to-point system. When a node “talks” on the network, it is…

  • 14.6 Network Topology

    If we want to connect two digital devices with a network, we would have a kind of network known as “point-to-point:” For the sake of simplicity, the network wiring is symbolized as a single line between the two devices. In actuality, it may be a twisted pair of wires, a coaxial cable, an optical fiber,…

  • 14.5 Optical Data Communication

    A modern alternative to sending (binary) digital information via electric voltage signals is to use optical (light) signals. Electrical signals from digital circuits (high/low voltages) may be converted into discrete optical signals (light or no light) with LEDs or solid-state lasers. Likewise, light signals can be translated back into electrical form through the use of…

  • 14.4 Electrical Signal Types

    With BogusBus, our signals were very simple and straightforward: each signal wire (1 through 5) carried a single bit of digital data, 0 Volts representing “off” and 24 Volts DC representing “on.” Because all the bits arrived at their destination simultaneously, we would call BogusBus a parallel network technology. If we were to improve the…

  • 14.3 Data Flow

    Buses and networks are designed to allow communication to occur between individual devices that are interconnected. The flow of information, or data, between nodes, can take a variety of forms: With simplex communication, all data flow is unidirectional: from the designated transmitter to the designated receiver. BogusBus is an example of simplex communication, where the…

  • 14.2 Networks and Busses

    This collection of wires that I keep referring to between the tank and the monitoring location can be called a bus or a network. The distinction between these two terms is more semantic than technical, and the two may be used interchangeably for all practical purposes. In my experience, the term “bus” is usually used…

  • 14.1 Introduction to Digital Communication

    In the design of large and complex digital systems, it is often necessary to have one device communicate digital information to and from other devices. One advantage of digital information is that it tends to be far more resistant to transmitted and interpreted errors than information symbolized in an analog medium. This accounts for the…