writing plc program

Hello;

There is a lot if help available on the web covering basic PLC programming, such as this site which I find quite well done:

https://accautomation.ca/five-steps-to-plc-program-development/

The sources of information for the different steps will dépend on your specific project. For example, electrical drawings for the machine or installation you want to control will help you define the I/Os and the symbol table. The client's functional description should guide you for the logic patterns you want to include in your program. And of course the different manuals for operation and communication for your equipment will be invaluable, especially if you take the time to study them properly when you face development issues while programing.

Hope this helps,

Daniel Chartirr

Write it out in pseudo code.  I prefer engineering graph paper for the first draft.  It let's me collect the overall architecture of the software.

I review the hardware configuration to help understand how to implement the feedback, controls, and special features like cyclic interrupts.

Once I have a general outline of the major pieces, I now have the FBs and FCs that gets called by OB1 (Main), and perhaps know about a few other OBs as well.

After that, it is generally a very good idea to export I/O tags from schematics software, and then import it into the input tags in TIA Portal for the project.  They should be named the same in both software systems (and in some situations, it is mandated they be identical).

Once the I/O tags exist, input and output parameters from some FBs/FCs can be assigned to real IO.

At this point, it is possible to download to the PLC the hardware and software and start real online development.  Inside OBs/FBs/FCs, simple logic can be temporarily stubbed in so block calls actually do something and you can watch process and data flow and look for misunderstandings in how things actually work compared to how you were told they worked.

U_2f93e501-02c0-4cab-8cfc-da7f088e631e

Hi dear experts,

Could you  please share your experience concerning any standard scenario for plc program writing for a machine from the first place? starting from where? writing symbol table, input output or ....?

I ask this since having a standard plan to organize the plc program is very important and helpful to prevent getting confused during writing or even for troubleshooting.

Thanks a lot.