Creating a project in Twincat

[Stuartjl 0]

Hi, can anyone give me any advice on creating a project using twincat. What i need to know is the best practice/procedure in creating a project. With Siemens S7 you create a project, then can setup the hardware first or second then start programming. Create your main then function blocks, functions etc. Any advice greatly appreciated. Stu Edited 11 May 2012 by Stuartjl

[RonHowell.com 1]

I start with setting up the I/O in the Device manager. Once I have the I/O completely set up, I set up the same I/O in TwinCat PLC (all tags including I/O have to be defined in the program like in C++ or Pascal). Once the PLC tags are set up you need to map the PLC tags to the Device Manager tags. Once the I/O is set up on both sides and linked I start defining internal tags, varriables, arrays, structures, routines, subroutines, functions, etc. TwinCAT takes a bit more fore thought and planning than a typical all hardware PLC. The good thing is that it allows you to create, link and schedule I/O updates the way you want and need the system to work. The bad thing is that you have these extra setup step that are transparent to the application programmer in traditional hardware PLCs. It is more like defining variables and linking elements from a library in a C++ program than it is your traditional PLC. Once the elements are defined and linked programming and program debug are not different than most PLCs. You do however need to recomplile and reload and go through a few extra steps if you need to make significant changes to the program or add/delete defined elements to the program. Please do not get me wrong. I am a big fan of the TwiunCAT system and it can do some fantastic things, but it is not a "beginners" PLC. Great for high speed motion and machines. I would be reluctant to use it on a large process system that cannot be shut down and restarted easily.