We will now look at the parts of a PLC system. When I was in school PLCs were just in their infancy. We were taught that the PLC consisted of the central processing unit (CPU), analog and digital inputs, and outputs. Everything was programmed with dedicated handheld devices and/or software devices on specialized hardware. We now have modern PLC systems that are capable of so much more. Let’s look at how we can now break up these modern PLC systems into the seven essential components.
CPU Inputs and Outputs (I/O) Analog I/O Specialty I/O Programming Tools HMI NetworkingContinue Reading…
Every manufacturer has there own software to program the programmable logic controller (PLC) or the human-machine interface (HMI). However, there are a few tools that are free which will help in the development of your PLC programs. We will look at three of these software tools and show how beneficial they can be to you.
Free PLC Software Tools
Synergy – Share Multiple Computer Systems
When programming, I usually will have my laptop for the ladder logic and my desktop for the screen software. Connecting the two together and using one mouse and keyboard saves me the aggravation of switching back and forth between the keyboards.
Synergy lets you easily share a single mouse and keyboard between multiple computers with different operating systems each with its own display without special hardware. It is intended for users with multiple computers on their desk since each system uses its own monitor(s). Redirecting the mouse and keyboard is as simple as moving the mouse off the edge of your screen. Synergy also merges the clipboards of all the systems into one, allowing cut-and-paste between systems. It works on Windows, Mac OS X, and Linux.
That’s right. The windows calculator can be a very helpful tool when it comes to programming PLCs. When you need to convert, hexadecimal to binary, BCD to hexadecimal or any other combination the windows calculator can do it for you.
Start the calculator. Start – All Programs – Accessories – Calculator
View the programmer calculator. View – Programmer (Alt + 3)
We can then choose Hex for our numbering system. Then Word for our length of the address. You will notice that the display will show the Bin equivalent along with the marking of bit 0 to bit 15.
7ABC base 16 = 0111 1010 1011 1100 base 2 = 31420 BCD
Note: I am using Windows 7, but all of the versions of window calculator have similar functionality.
Windows HyperTerminal – Free PLC Software Tool
Serial communication can be difficult using PLC. HyperTerminal can be used to monitor the communication being sent from or to the programmable logic controller. Just hook up to the serial port and program HyperTerminal to monitor the port. Set the correct Data Bits, Baud Rate, Parity, Stop Bits, etc. Viewing the information on the monitor will assist you in seeing the exact data being sent to, or received by the PLC.
HyperTerminal was no longer sent with windows when Windows 7 was introduced.
Hype Terminal is fully functional replacement of HyperTerminal, perfect for GSM and GPS debugging, works with AT Commands. You can use Hype Terminal to help debug source code from a remote terminal. You can also use Hype Terminal to communicate with older character-based computers. Hype Terminal is designed to be an easy-to-use tool and is not meant to replace other full-feature tools available on the market.
If you’re like most of my readers, you’re committed to learning about technology. Numbering systems used in PLC’s are not difficult to learn and understand. We will walk through the numbering systems used in PLCs. This includes Bits, Decimal, Hexadecimal, ASCII and Floating Point.
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