Controls communications
Communications today are mainly with the help of electronic networks and equipment suppliers have built a number of proprietary protocols, which allows certain devices to communicate. Industry moves away from your own schemas management and centralized systems. Manufacturers use open operating systems and parts for the creation of products that have improved the reliability, flexibility, system cost and performance. LON (Local Operating Network) and MODBUS protocols are examples of open access protocols intended for General use network control solutions. The protocols refer to the structure of signals, which are used in communication. These structures can be passed on through many different media. Examples
- Voltage of power network, as a rule, 230 V, but sometimes 115 V
- Low voltage, mainly, 24 V D.C.
- Low voltage electronic circuits
- Telephone cable
- Pneumatic
- Optical fibers
- Optical infrared
- Radio
- Internet
The input signals, the controllers can be transmitted in several ways.
They include:
- Mechanical tools - rods, levers and cables
- Pressure of a liquid
- Low voltage, thermocouple (Mac)
Mechanical devices require careful installation to ensure that there is no distortion of details. This is especially true in the case of a flap mechanisms that need maintenance and periodic checks to make sure that they work properly.
Where the pressure of the liquid is carried out using a capillary tube, for example, with thermo-static expansion valve or a pressure switch, the pipes should be established with regard to risk his irritation against the metal edges and wiping. Tube pressure gauges usually in plastic, but can be copper. They should be carefully inspected for leaks because they are carriers of very low pressures.
Voltage network communications shall be in accordance with the IEE Wiring or the relevant safety regulations. In particular, they may interfere with the telephone, computer and other electronic signals is in or near the same channel. Similarly, electronic control signals can suffer interference. Thermocouple signals are very low DC voltage and must be met as far as possible with unbroken conductors. Terminal boxes should be compact and isolated from sudden temperature changes. Terminals must be tight.
Pneumatic controls are used widely in dangerous situations, such as chemical plants and oil refineries. The same risk in irritation of the acts of the capillaries. Pneumatic tube systems, as a rule, in copper and safe.
Optical fiber is still very much in use, but there is no interference between them and the electrical signals of any kind. For this reason their use is likely to become more common. Line-of-sight optical signals that require intervention is not inserted at any time. Such points are easy to notice during installation and commissioning, but not so obvious if a malfunction occurs at a later date.
Remote plant sometimes controlled by, or are controlled by radio communication. It is now largely forced out of Internet systems. On-line systems allow users to display the control panel for remote systems in your browser to monitor or control adjustments...
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