The burner has a main switch with ON and OFF positions. There is also a START push button. To start the burner, turn the main switch to the ON position and press the START button. Then the flue gas fan starts first. When the fan has developed a sufficient negative pressure (the contact of the pressure sensor closes), the oil burner starts. After the oil burner starts, the ignition current transformer turns on for 3 seconds. Now (within 3 s) the flame guard must see the flame (closing contact) in order for the burner to stay on. If the flame guard does not see the flame, the oil burner stops, but the flue gas blower remains on. At the same time, the "BURNER FAILURE" warning light lights up. The warning light can be turned off when the main switch is turned to the OFF position; at the same time, the flue gas fan stops. Turning the main switch to the OFF position always stops all functions of the burner.
Sounds like a homework problem. What have you tried?
Yes. It's homework. Can you please help with this. It would be great help if you help me
You didn't answer the question, "What have you tried?"
Why did you mark Phil's answer as "Solution"? That means your question has been answered and you don't need any more help!
I'm happy to help, but you have to try. Just giving a student a solution doesn't help any learning.
Lay out and show us an attempt to solve this, and we can point out flaws and offer techniques on a point by point basis.
Do it online if you don't have professionals software. I've seen PLC Fiddle recommended here before.
Edit: This PLC Simulator might be better: it appears to allow you to save and reload from files.
Here's the first rung to get you started:
He posted the same question here,
And received the same response on PLCTalk. Show some work and we will help, but we arent doing your homework for you. It teaches you nothing to be given answers.
This is a forum for Ignition - a SCADA design software. What you're asking is related to PLC programming. They are 2 completely separate things. Also, it's bad practice to ask someone else to solve your problem for you without even trying yourself.
i am sorry for asking help with trying. i am unable to reply you through my post so i am writting here. i have tried my homework. could you please check my work
Ok. You discarded my recommended first rung. You certainly will want to bring it back.
Some points:
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A two-position switch, like the main power switch, are generally only wired to a single input, for the "ON" case. A normally closed contact can reference that for the opposite without another input. Such switches, unless documented otherwise, stay in the last position set by the operator. It is a good practice to ensure the name of such signals ends with SW or Switch.
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A physical pushbutton, like the Start button, are generally momentary, meaning they are "ON" while pressed, and "OFF" when released. In my sample rung, I used a branch containing the fan control output to "seal in" around the start button, since the operator will release that and it will turn off. Again, it is good practice to ensure the name of such signals ends with PB or Button.
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Your process description indicates that the burner cannot start until the fan has developed differential pressure, but doesn't say that the burner should turn off if that goes away. You probably need a "seal in" branch around the pressure switch in the rung that drives the burner.
... More after your next draft ...
i did not get what are you saying. can you please clarify it.
What Phil is saying is you've listed both "MAIN SWITCH ON" and "MAIN SWITCH OFF" but typically these are a single "tag" in the PLC which you could name something like "MAIN_SW" or "MainSwitch". You use the XIC contact/instruction for closed/on and the XIO contact/instruction for open/off.
The same goes for the momentary pushbutton.