Communiquez avec les autres et partagez vos connaissances professionnelles

Inscrivez-vous ou connectez-vous pour rejoindre votre communauté professionnelle.

Suivre

What should be the basic knowledge to learn PLC?

user-image
Question ajoutée par MOHAMMED JAMSHED ALAM , MEP Supervisor , EI-Seif Engineering & Contracting Co. Ltd.
Date de publication: 2014/10/01
Utilisateur supprimé
par Utilisateur supprimé

What?

Why?

When?

Where?

Types?

Features, software?

How to configure?

How to program?

 

Walid Nassif
par Walid Nassif , Operation Manager , Wally Nassif Contracting

 

Learning about PLC’s is understanding  what you are trying to control, a single PLC can be programmed to replace thousands of relays. PLCs can be programmed using standards-based programming languages.  A graphical programming notation called Sequential Function Charts is available on certain programmable controllers.

 

Eyad Abbas
par Eyad Abbas , Facilities (Service) Manager , MEP , Alghanim Industries

Programming and troubleshooting skills

Bulbasa Ionel - Leon
par Bulbasa Ionel - Leon , PLC Programmer , IPTE Sibiu

First you have to understand the logic that rules the CPU - central processing unit - of an PLC.

A program for PLC is build in steps (rungs), like a ladder. This is why it is called: "ladder logic programing ".

When a program is running, the CPU first reads all the rungs and after that takes action. So, at the end of readings "he" close/open contacts or turn on/off relays based on how the process is altered in time.

 

Let's take a short example: we have a button B whit a NO (normal open) contact and a motor M. We start the program and the CPU starts to read. First it sees that B is not pressed so he decide not to turn on M.

He continue the readings and taking decisions until the CPU is turned off. So, after a while we press B. Now, CPU see B pressed, so at the end of the reading will turn M on and keeps it on as long as we keep B pressed.

When we depressed B, by removing the finger, the CPU reads that and at the end of the reading takes the decision to turn M off!!! Notice here that short delay between depressing B and turning off M?!? This can became very frustrating when programming!!!

 

Above is a simple example but the situation becomes complicated when the rungs are much more complex!

But, in essence, if you understand this logic, a PLC course, practice and time is what you need!

For more information you can read IEC61131 part3!

Good luck!

Tom Escosa
par Tom Escosa , HVAC Engineer , ADNOC

There are two basic knowledge in order to adapt the PLC, One is you must have a thorough knowledge and experience in troubleshooting MEP system and the second is, you know how to work on computer system. Without these two (2) basic knowledge, you will find yourself a hard-time working in PLC. Hope this helps give you an idea.

More Questions Like This