Ladder logic programs mimic the electrical circuit diagrams used for wiring control systems in the electrical industry. The basic purpose of an electrical control system is to determine whether a load should be turned ON or turned OFF, under what circumstances and when it should happen. To understand a ladder program, just remember the concept of current flow - a load is turned ON when the current can flow to it and is turned OFF when the current could not flow to it.

Chapter 8 in the TRiLOGI Programmer's Reference Guide has a short introductory course on Ladder Logic Programming. For a little more reading, please download the Chapter below: www.tri-plc.com/appnotes/Chapter8.pdf

Read more discussions : http://www.tri-plc.com/yabbse/index.php?board=2;action=display;threadid=303  

Most PLCs in the industry are programmed by pure "Ladder Logic". Ladder Logic language has its strength in handling single bit digital I/O programming, but it is awkward to handle data processing where numerical data needs to be manipulated.

On the other hand, desktop computers are typically programmed by high-level languages such as BASIC, C, PASCAL, C++, Java etc. These powerful programming languages are designed for data processing, but they are not oriented towards flipping single bit digital I/Os.

By combining these two most important branches of programming languages into one single, seamless entity, we created the industry's first "Ladder + BASIC" language that can easily handle sophisticated tasks with just a few lines of codes. Please click on the the link below to see some examples of how simple it is to perform a fairly sophiscated job using Ladder+BASIC:

http://www.tri-plc.com/examples.htm

Because of the power and simplicity accorded the programmer, iTRiLOGI :

    * reduces a company's dependency on highly-skilled programming engineers
    * shortens programming leadtime and gets projects working sooner
    * makes troubleshooting easier due to the ability to view ALL internal variables in real time using the iTRiLOGI the On-line monitoring capability.
    * allows rapid testing of program changes using built-in offline SIMULATOR
    * allows remote troubleshooting locally or via LAN or over the INTERNET!
    * performs sophisticated communication with 3rd party MODBUS devices, HMI, SCADA, barcode reader, smart-card reader, serial printers etc.

1. Click this link : http://www.tri-plc.com/trilogiintro.htm to learn more about Ladder+BASIC.

2. You can register to download a free, fully working copy of the Educational Version of iTRiLOGI 5.xx or 6.xx & Programmer's Reference from the following link: http://www.tri-plc.com/trilogi.htm

The Educational TRiLOGI offers a fully functional offline simulator which allows you to create your own ladder+BASIC program and perform near 100% testing on your PC without purchasing any PLC hardware.

- For a quick evaluation without installing the software, you can try out an Applet version of TRiLOGI software which will run off your Java-enabled browser at the following link: http://www.tri-plc.com/TLeval/runTRiLOGI.htm

1. You can click on the "Help" menu in iTRiLOGI 5.xx or 6.xx software (a free educational version available for download from http://www.tri-plc.com/trilogi.htm). Select "Content" and you will find a "Ladder Logic Programming Tutorial" where you can follow the tutorial to create your first Ladder + BASIC program.

2. There are many well-documented example programs in your TRiLOGI installation folder: C:\TRiLOGI\TL6\usr\samples. You should open  up these sample programs and read the comments carefully, then run  simulations to test the functions described in these   programs. That is the best way of learning our Ladder and Ladder+BASIC programming method. There are also several subfolders in the ...\samples folder that provide numerous examples for interfacing to XServer, I-70xx and some pure ladder logic programs.
        
3. Professor TC Chang of Purdue University has written a TRiLOGI 5.3 Tutorial for use by his students as teaching material and he has kindly allowed us to share his work with anyone interested in TL5 Tutorial. You can click on the following link to obtain the tutorial: http://www.tri-plc.com/TCChangTL5_Tutorial.pdf

4. Kevin Collins of Institute of Technology Sligo (Ireland) has written a book named "PLC Programming For Industrial Automation". Many examples in the book were created and tested using Internet TRiLOGI simulator 5.32 and therefore you can test the topic immediately using the free TRiLOGI simulator software. The book is avaliable at Amazon.com. For more information on the book please visit www.amazon.com

TRi PLCs are programmed through a connection to any PC with an RS232 serial connection port and running on Windows or even DOS. The new F-series PLCs can also be connected by Ethernet to a network and programmed over a local network or the Internet using a PC. You will then just need a production copy of TRiLOGI and a DB9 cable* (or Ethernet cable for the F-series PLCs) to make the connection. As such, your first purchase of a TRi PLC should always be (or include) a Starter Kit, which includes both cable (DB9 only) and software as well as installation and programming manuals.

There are two basic classes of TRiLOGI software which are supplied with the respective starter kits:

1. iTRiLOGI version 5.xx or 6.xx supports LADDER+BASIC capability and is the only software needed to program any of the M-series or F-series PLC models.

2. WinTRiLOGI version 3.5x supports only pure Ladder logic programming (i.e. no BASIC) and is needed for programming any E10 or H-series PLCs.

1.  Both iTRiLOGI and WinTRiLOGI runs on Windows 98,Me,2000,NT,XP & Server2003.
      
2. A DOS version of TRiLOGI is bundled with the iTRiLOGI or WinTRiLOGI CD-ROM in the Starter Kit at no charge. This allows users who still use PC-DOS to program the PLC.
      
3. Linux - Although iTRiLOGI and WinTRiLOGI are both written in pure Java, we currently do not support them to run on Linux platform due to the subtle differences between Windows and Linux versions of Java Runtime Environment, which leads to the instability of these software when running on Linux platform.