1 / 18

Program Logic Controller

Program Logic Controller. PLCs were invented in answer to the needs of the automobile industry, and were introduced in the late 1960’s. They were designed to take the place of older, more complicated relay based equipment systems. ｩ Emil Decker, 2009. Program Logic Controller.

winona
Download Presentation

Program Logic Controller

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Program Logic Controller PLCs were invented in answer to the needs of the automobile industry, and were introduced in the late 1960’s. They were designed to take the place of older, more complicated relay based equipment systems. ｩEmil Decker, 2009

  2. Program Logic Controller Relays were invented in 1835 by Joseph Henry. Relays use an electro- magnet to close or open a switch. This circuit is isolated from the power that runs through the main circuit involved. ｩEmil Decker, 2009

  3. Program Logic Controller This allows a low voltage relay to “throw the switch” on a higher voltage line and keep the operator safe. Relays are used in many electrical systems, including automobiles. ｩEmil Decker, 2009

  4. Program Logic Controller Relays are complicated, and systems using a lot of them tended to be very costly to operate and maintain. If production requirements changed, then the control system had to change also. ｩEmil Decker, 2009

  5. Program Logic Controller The mechanical relays had a limited lifespan, and troubleshooting them were often problematic. Imagine a system using literally thousands of relays. Typical Relay ｩEmil Decker, 2009

  6. Program Logic Controller By replacing bulky mechanical components with solid state circuits under the control of a microcontroller makes a lot of sense. ｩEmil Decker, 2009

  7. Program Logic Controller The microprocessor is the brain of a PLC system. It consists of the microprocessor, memory, and circuits necessary to store and retrieve data from that memory. It also includes communications ports to other devices. ｩEmil Decker, 2009

  8. Program Logic Controller Processors vary in their capabilities to control devices. Some control as few as 6 inputs and outputs (I/O) and others control as many as 40,000 or more. ｩEmil Decker, 2009

  9. Program Logic Controller One processor can control more than one process or manufacturing line. Processors are often linked together in order to provided continuity throughout the process. ｩEmil Decker, 2009

  10. Program Logic Controller Ram, or random access memory, is necessary for PLCs. Like computers, this is the area where all instructions are stored during operations. Everything happens in RAM. ｩEmil Decker, 2009

  11. Program Logic Controller ROM, or read only memory, is important too. Instructions burned into ROM cannot be changed. This is where the basic program is stored. You load this and your routines into RAM to run them. ｩEmil Decker, 2009

  12. Program Logic Controller EEPROM, or Electrically Erasable Programmable Read Only Memory, is like ROM, but with the correct equipment, can be reprogrammed, making it more versitile. ｩEmil Decker, 2009

  13. Program Logic Controller Input modules are simply what they say they are. The input signals, whether via a push button, limit switch, electric eye, or an electrical input . ｩEmil Decker, 2009

  14. Program Logic Controller If there are input modules, then there must be output modules as well. LED readouts, solenoids, relays, DC or AC outputs to machinery, are a few options you have for output. ｩEmil Decker, 2009

  15. Program Logic Controller PLCs, at their simplest, are ON / OFF switches, sequentially operated to send signals to an output device. ｩEmil Decker, 2009

  16. Program Logic Controller Electromagnetic interference (EMI) and Radio Frequency Interference (RFI) can cause problems in most solid state control systems, and PLCs are not immune. ｩEmil Decker, 2009

  17. Program Logic Controller PLCs are used in a variety of applications from manufacturing assembly lines to equipment control in the harshest of environments. Coal mining machine controlled by PLCs ｩEmil Decker, 2009

  18. Program Logic Controller • Lamps • Relays • Motor controllers • Solenoid valves • Machine inputs • Other inputs PLC Power supply Programmable Logic controller • Switches • Sensors • Machine • outputs • Other • outputs PLC input modules PLC processor PLC Output modules Standard networks PLC Communications modules Proprietary networks Smart I/O interfaces PLC special Purpose modules Remote racks ASCII I/O interfaces ｩEmil Decker, 2009

More Related