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Old June 13th, 2018, 06:39 AM   #1

smithy1080 is offline
Join Date: Jun 2018
Location: Sydney
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Stir tank for 5 minutes every hour

Hello everyone,

i'm very new to PLC's.

I have a VFD hooked up to a tank agitator motor, the VFD is connected to an output on my Allen Bradley Micro850.

I need to stir the tank for 5 minutes, and then off for 55 minutes and then repeat. What is the best way to do this? Ladder logic or write a structured text program? I'm using Connected Components Workbench. I've discovered the Timer On and Timer off functional blocks and also Pulse timer. Having trouble getting it to work....


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Old June 13th, 2018, 06:48 AM   #2

gclshortt is offline
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Location: Cobourg
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It sounds like you need an on-delay timer with a pulse timer.
Here is a couple of videos that will help you out.
Pulse Time
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Old June 13th, 2018, 08:10 AM   #3
Vlad Romanov
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Vlad Romanov is offline
Join Date: Sep 2017
Location: Los Angeles
Posts: 92
I would definitely go for ladder logic for such a simple application.

As you've mentioned in your post, you should be using basic TON timers for this. (You don't even need the TOF)

Here's an implementation of this logic.
NOTE: I tested with much smaller values on the timers (so that I don't wait for one hour), you will need to change those to whatever time scale you're using.

Note2: does not seem like my image is being posted... Here's the link:

Let me know if that makes sense...
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Old June 13th, 2018, 08:42 AM   #4
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damica1 is offline
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This is how I would probably do it.
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Old June 13th, 2018, 09:10 AM   #5
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janner_10 is offline
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Keep it simple and use the tools included.

Ladder logic and use TONOFF Timer, its exactly what it was designed for.
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Old June 13th, 2018, 09:18 AM   #6
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saultgeorge is offline
Join Date: Jul 2015
Location: Detroit
Posts: 185
Hi, and welcome to the forum. I just completed a job where a slurry tank had to be stirred just as you describe, only of course with different time values. It's in 5000, but I'm sure you can get it into whatever the micro uses..500? I also had CCW and made all the keypads, readouts, etc. If the info these pros have provided for you gets you close but not a touchdown, let me know and I'll send you a few rungs and the HMI. Good luck and again welcome to the forum.
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