Online PLC and Controls Forums
control.com - integrator and controls forum that started with an open source project.
MrPLC forum - PLC specific forum
Automation Web - Created by a user when Rockwell forums went down. Let’s help get this one started.
Looks like Automation Web died.
plcs.net- Forum plus an online simulator
EZAutomation- Low-cost PLC/HMI/etc. Really good for small standalone projects.
Useful Reddit subs:
PLC(Programmable Logic Controllers)
ECE(Electrical and Computer Engineering)
AskElectronics(General Electronics Questions)
eebooks(Free and Legal ECE Text Books)
ECE Component exchange(ECE Parts Swap)
Manufacturing(Manufacturing Industry News)
engineering(General Engineering)
Other online PLC Forum resources are given below:
If you are interested to know about PLC course and its advantage then go through here: PLC SCADA Training in Noida |Industrial Automation Training in Noida | CETPA INFOTECH
Some posts are 15 years old. Not all of them survive. Welcome to the interwebz.
I have used LogixPro for about 5 years to teach introductory PLC programming exercises at a local university. The software's UX is laughable, but I've always been successful using it to teach the fundamentals, and haven't found a better alternative (for the price). Inexpensive automation/PLC resources are hard to find, and I would recommend this to anyone looking for a starting point to learn PLC programming.
I always recommend that people complete the first 4 exercises using only OTE instructions and stay away from OTL/OTU. Then after they have mastered the fundamentals, go back and solve them with latched and unlatched instructions.
LogixPro Allen Bradley simulator
Student documentation and reference material here