plc programming
plc programming
(OP)
Anybody please help me,
I am new to plc, but after learning basics i got project to work on it.I was introdced with electrical cad diagram from which i should design ladder diagram.Since I learned PLC with concepts and conditions never came across to build ladder logic with electrical diagram.Pls anyone come forward and help me with some examples so i can easily understand the concept to get logic conditions from electrical diagrams.
I am new to plc, but after learning basics i got project to work on it.I was introdced with electrical cad diagram from which i should design ladder diagram.Since I learned PLC with concepts and conditions never came across to build ladder logic with electrical diagram.Pls anyone come forward and help me with some examples so i can easily understand the concept to get logic conditions from electrical diagrams.





RE: plc programming
1) Programing a PLC requires you to fundamentally understand what the circuitry and hardware can be made to do and what it needs to do. If you cannot find a way to understand the electrical diagrams to this level you cannot proceed.
2) Once you understand the electrical diagram you need to work from a specification. The specification is a document that describes the system's expected function. Think about a dishwasher. It will have several electrical apparatus that need to work in an organized, sequential manner to realize its proper function. A specification will be a recipe that explains all the states the dishwasher needs to pass thru to accomplish its task. As the PLC programmer you would normally look to the customer. This could also be your project leader or it could be yourself - if you're expected to fully understand the system. Someone needs to develop a detailed written specification.
To summarize: A PLC programmer is not handed an electrical diagram and told, "Program the PLC". He is handed an electrical diagram or list and a detailed specification. From these he or she can then proceed to program the PLC in a deliberate, successful manner.
Keith Cress
kcress - http://www.flaminsystems.com
RE: plc programming
RE: plc programming
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RE: plc programming
RE: plc programming
Back to the dishwasher:
Prewash cycle
1) Fill
* Turn on water valve
* Turn on Prewash light
* Wait for water level to reach -full-
* Start time-out timer if fill switch or water source have failed
2) Once full
* Turn off water valve
* Run motor forward
* Do for X minutes
* Stop motor
Prewash Drain
* Run motor in reverse
* Start time-out for pump out
* Stop motor
* Turn off Prewash light
Etc etc until done with all states.
Then, you need to understand your circuit diagram to understand how you can control the various electrical apparatus with the PLC.
Keith Cress
kcress - http://www.flaminsystems.com