help with ladder diagram

I need to draw a ladder diagram for a tank being filled three times a day but not within 6 hours after each fill. Can anyone help me? I am at a very basic level

I don't all the details of your equipment, but you have several options. You could use a 6 hour timer that starts after the tank is filled and make it where the timer has to be completed for the tank to be able to be filled again.

Timers have a slight error (probably not enough to matter in this case) but if you wanted to be fancy/more accurate, you could use a realtime clock. A realtime clock would be a better option if you wanted to fill the tanks a certian time every day, such as 8AM, 4PM, and Midnight.

It all depends on what kind of hardware you are using, the type of control system you are using, what is currently implemented, and what are the other details needed to control the system.

How about you fill it at 6:00 A.M, again at 2:00 P.M, and then the last fill at 10:00 P.M.
In order to fill the tank, do you have to open a valve, or turn on a pump?
Is there a valve that has to open to Empty the Tank?
Do you have a sensor that shows when the Tank is Full?
Do you have a sensor that shows when the Tank is Empty?
What brand of PLC is not critical, but it would help to know this.

What have you already learned in class?

State the problem as a series of statements.

Six hours is 21,600 seconds.

If (tank needs filling) AND NOT (still timing) then (fill the tank).

If (tank done filling) Then reset the timer and restart timing.

Construct a statement for how many times a day it can fill.

Next define what (tank needs filling) and (tank done filling) means. For example, if the tank has a single float switch that closes when the tank is full then (tank needs filling) = NOT FLOAT SWITCH and (tank done filling) = FLOAT SWITCH. Then write down the input address for the float.


Then define what (fill the tank) means. For example if the tank is filled by a pump then (fill the tank) means turn on the PLC output to run the pump. Write down the PLC output for the pump.

After you do that then you'll have a good idea of what needs to be done and you can convert it to PLC code. Once you have described the problem with specific statements if you need help coding the statements come back and we'll help walk you through it.

ildi2000 said:

I need to draw a ladder diagram for a tank being filled three times a day but not within 6 hours after each fill. Can anyone help me? I am at a very basic level

Click to expand...

If this is homework - be honest - and post what you have done so far, even if it is a scribble on a piece of paper!

ildi2000 said:

I need to draw a ladder diagram for a tank being filled three times a day but not within 6 hours after each fill. Can anyone help me? I am at a very basic level

Click to expand...

YES

we can all help you

I wonder how to handle a process of this kind once the power goes out.
Tank is being filled and the power goes out.
Tank fill time is missed during the power outage.
?
Guess I not too much of help to your solution.

Adam303 said:

I wonder how to handle a process of this kind once the power goes out.
Tank is being filled and the power goes out.
Tank fill time is missed during the power outage.
?
Guess I not too much of help to your solution.

Click to expand...

you could employ some people with straws to stop the tank from overflowing

Adam303 said:

I wonder how to handle a process of this kind once the power goes out.
Tank is being filled and the power goes out.
Tank fill time is missed during the power outage.
?
Guess I not too much of help to your solution.

Click to expand...

UPS

Nuff said

you could employ some people with straws to stop the tank from overflowing

Click to expand...

Funny

straws? as in straws so they could drink from the tank to stop it from filling?

(facepalm)

jommunar said:

straws? as in straws so they could drink from the tank to stop it from filling?

(facepalm)

Click to expand...

Yes
even the type with the spoon shape on the end.
that way you can also spoon it out