A PROGRAMMABLE LOGIC CONTROLLER (PLC) is an industrial computer control system continuously monitors the state of input devices and makes decisions based upon a custom program to control the state of output devices.
Almost any production line, machine function, or process can be greatly enhanced using this type of control system. However, the biggest benefit in using a PLC is the ability to change and replicate the operation or process while collecting and communicating vital information.
Another advantage of a PLC system is that it is modular. That is, you can mix and match the types of Input and Output devices to best suit your application.
The first Programmable Logic Controllers were designed and developed by Modicon as a relay re-placer for GM and Landis.
The Central Processing Unit, the CPU, contains an internal program that tells the PLC how to perform the following functions:
The following table shows a list of commonly used Acronyms that you see when researching or using your PLC.
|ASCII||American Standard Code for Information Interchange|
|BCD||Binary Coded Decimal|
|CSA||Canadian Standards Association|
|EIA||Electronic Industries Association|
|HMI||Human Machine Interface|
|IEC||International Electrotechnical Commission|
|IEEE||Institute of Electrical and Electronic Engineers|
|I/O||Input(s) and/or Output(s)|
|ISO||International Standards Organization|
|LSB||Least Significant Bit|
|MMI||Man Machine Interface|
|MODICON||Modular Digital Controller|
|MSB||Most Significant Bit|
|PID||Proportional Integral Derivative (feedback control)|
|RTU||Remote Terminal Unit|
|SCADA||Supervisory Control And Data Acquisition|
|TCP/IP||Transmission Control Protocol / Internet Protocol|