What
Is A Programmable Logic Controller (PLC)? (continued
from page
1)
What Do I Need To Consider When Choosing A PLC?
There are many PLC systems on the market today. Other than
cost, you must consider the following when deciding which
one will best suit the needs of your application.
- Will the system be powered by AC or DC voltage?
- Does the PLC have enough memory to run my user program?
- Does the system run fast enough to meet my application’s
requirements?
- What type of software is used to program the PLC?
- Will the PLC be able to manage the number of inputs and
outputs that my application requires?
- If required by your application, can the PLC handle analog
inputs and outputs, or maybe a combination of both analog
and discrete inputs and outputs?
- How am I going to communicate with my PLC?
- Do I need network connectivity and can it be added to
my PLC?
- Will the system be located in one place or spread out
over a large area?
PLC Acronyms
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 |
| DIO |
Distributed I/O |
| EIA |
Electronic Industries
Association |
| EMI |
ElectroMagnetic Interference |
| 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 |
| LL |
Ladder Logic |
| LSB |
Least Significant Bit |
| MMI |
Man Machine Interface |
| MODICON |
MOdular DIgital CONtoller |
| MSB |
Most Significant Bit |
| PID |
Proportional Integral
Derivative (feedback control) |
| RF |
Radio Frequency |
| RIO |
Remote I/O |
| RTU |
Remote Terminal Unit |
| SCADA |
Supervisory Control
And Data Acquisition |
| TCP/IP |
Transmission Control Protocol / Internet
Protocol |
| |
portions of this tutorial contributed
by www.modicon.com and www.searcheng.co.uk |
