Top 7 Problems with Beginners using Ladder Logic

Here are the top 7 problems and concepts beginners struggle with using ladder logic (Ladder Diagram). Ladder logic is a programming language used in PLCs, and it is based on the graphical representation of electrical relay logic circuits. Many beginners struggle with ladder logic because it requires a different mindset than traditional programming languages like C++, Python, or Java.
We will look at the seven common issues beginners face due to a lack of understanding of ladder logic. Stick around until the end to see the bonus problem that is not well understood. Let's get started.
More information can be obtained at our website. This includes all of the links mentioned in this video.
accautomation.ca/top-7-proble...
Previously in this PLC Learning Series:
PLC Training Series - Tutorial for Everyone
accautomation.ca/plc-training...
• PLC Training Series - ...
What are Inputs?
accautomation.ca/plc-learning...
• PLC Learning Series - ...
What are Outputs?
accautomation.ca/plc-learning...
• PLC Learning Series - ...
Memory Backup
accautomation.ca/plc-learning...
• PLC Learning Series - ...
Understanding Number Values
accautomation.ca/plc-learning...
• PLC Learning Series - ...
Program Cyclic Scan
accautomation.ca/plc-learning...
• PLC Learning Series - ...
Programming Steps
accautomation.ca/plc-learning...
• PLC Learning Series - ...
HMI - Interfacing
accautomation.ca/plc-learning...
• PLC Learning Series - ...
00:00 Top 7 problems with beginners using ladder logic
01:04 Thinking procedurally instead of in parallel
01:37 Misinterpreting contacts and coils in ladder logic
02:16 Difficulty (problems) with timers and counters
02:49 Overlooking scan cycle considerations
03:32 Lack of knowledge about memory types
04:29 Not leveraging advanced instructions
05:07 Difficulty in troubleshooting
05:38 Bonus - Developing a PLC Program
PLC Beginner’s Guide to PLC Programming
There are many different PLC manufacturers with different hardware and software. All of the programmable logic controllers have similar basic features. Here is how I would approach learning about basic PLCs.
accautomation.ca/programming/...
Once you are familiar with the basics of the PLC, you will then learn specifics for the controller you will be programming.
This is the easiest way to learn about PLC programming.
ACC Automation
www.accautomation.ca/

[@ACCautomation]

More information can be obtained at our website. This includes all of the links mentioned in this video. accautomation.ca/top-7-problems-with-beginners-using-ladder-logic/ PLC Beginner’s Guide to PLC Programming There are many different PLC manufacturers with different hardware and software. All of the programmable logic controllers have similar basic features. Here is how I would approach learning about basic PLCs. accautomation.ca/programming/plc-beginners-guide/ Once you are familiar with the basics of the PLC, you will then learn specifics for the controller you will be programming. This is the easiest way to learn about PLC programming. ACC Automation www.accautomation.ca/

[@parelectricengineeringllc1816]

Another great video on ladder logic. Thanks !!

[@ACCautomation]

Thank you for the comment. I appreciate it. Garry

[@mikeglide1292]

This is wonderful information. Especially for folks who are coming into programming through the back door. I started with relay logic. Then learning to modify relay logic. Followed by converting simple machines from relay logic to a PLC. This information would have made that a less bumpy ride. But it really helps when you find yourself upgrading and retrofitting a machine programmed by a real programmer. Thank you for this.

[@ACCautomation]

Hi @mikeglide1292 I agree. I also learned the hard way. This information is important to beginners learning about ladder logic (ladder diagram) programming. Thank you for the comment. Garry

[@gvenagas]

I'm sorry if I'm wrong because I'm not an expert in PLCs, but as I understand the memory bits of a PLC simulate physical switches and push buttons. By their nature, the bits are in state (0), which is why a MAKE command coincides with a switch that changes from an open state (0) to (1) when the switch is pressed by user, but this does not happen with a BREAK command that in order to is valid, the PLC memory bit which, as we said, is in a normal state (0) should become (1), that is why the electrical continuity of the circuit does not coincide with the logic BREAK command of the PLC, which in order to be valid, the memory bit must from (0) to (1) when the user presses the switch. I hope I didn't make the situation worse.

[@ACCautomation]

Hi @gvenagas, Think of memory in the PLC as all bits. Yes, some are for physical inputs and outputs. We can combine these and create bytes, words, double words, etc. These bits can then be interpreted as on/off (1/0), numbers (Binary, Hex, BCD, etc.), ASCII, etc. When you are saying BREAK and MAKE commands, this is Make-Before-Break which is a way to think about how physical IO behaves in the PLC. This is due to the scan of the PLC. Inputs are read, logic is solved, communication happens, and outputs are set based on the logic all at once. Here is a post that will discuss the scan of the PLC. accautomation.ca/plc-learning-series-program-cyclic-scan/ I hope this answers your question. Regards, Garry

[@gvenagas]

@@ACCautomation Very clear explanation! Thanks for your reply! Your videos are excellent!

[@hamzakourta4509]

I am one of those who struggle from the first problem, I find it challenging to make sequences with the simultaneous nature of the language how can I solve this problem?

[@ACCautomation]

Hi @hamzakourta4509 I would start by learning more about the scan with some simple logic. Here is a post on synchronous PLC scanning. accautomation.ca/how-ladder-logic-program-scan-works/ Here is another on the cyclic nature of the PLC scan. accautomation.ca/plc-learning-series-program-cyclic-scan/ This post will give ladder logic examples to explain the PLC scan. accautomation.ca/understanding-the-plc-program-scan/ I hope this helps you out. Regards, Garry

[@hamzakourta4509]

@@ACCautomation thank you so much