Mennis (Customer) asked a question.
Creating batch controller to read flow meter and control total gallons of water into tank.
I am new to PLC work but I have an application that I am filling small tanks (120-300 gal.) with hot water. I have started with 7 batch controller from a company but am having troubles with them. When they work they work fine, durability seems to be a problem ( not sure if it is the fault of the controllers or if it is a power quality problem as we are losing boards in them??? )
- However, in my mind I would like to set up a system that would be more simplistic for them.
- I see a system that they could push a button to start a program and then have a dial ( potentiometer ?) to dial in an amount 0-300 gallons.
- Save amount and then use a second button to start the process. Which is opening a motorized ball valve. I am currently using a Sika Flow meter that reads a pulse at 400 pulses per 1 gallon. Once the amount is obtained it would stop the valve.
- I would need a display for them to see the amount and total. I hesitate to use an HMI as it is quite wet and humid conditions and the hands touching the display are usually dirty.
- I have a 4 button remote external switch box that I would like to reuse if I could.
- Any thoughts are welcome!
- .
instead of a potentiometer, you could use an up/down pushbutton set connected to I/O to set the desired level, then another pushbutton on the panel to start filling. in a humid, dirty environment you will have issues with a potentiometer. you could still use an hmi in this scenario, with a proper cover (basically using it for a display), just have push buttons connected to inputs to change parameters instead of having to use the touch screen. i could see this working quite well with a plc and some code.
Is this a washdown application where it will be deliberately sprayed with high pressure water? If not, put a spare HMI on the shelf. It's easier, cheaper, scalable and easy to change. Plus with what you describe, you wouldn't even need to worry about navigating away from a single screen. 4 or 5 buttons would cover it.
I have these in a number of non-ideal environments. Don't forget the gasket.
https://www.automationdirect.com/adc/shopping/catalog/hmi_(human_machine_interface)/c-more_micro_panels/3_inch_panels_-a-_accessories/ea3-s3ml-rn
Then a simple CLICK PLC to run your sequence.
Thank you for the idea? I will definitely dig into that!!
This is in a dairy calf raising operation. They are using the water to mix with milk replacer which is a powder. The tankers are being pulled with Kubota UTVs and when they are done feeding everything has to be washed out and down. They use the hot water to do this as everything is ice cold ( we're in northern Wisconsin ) so it gets very "tropical" in the place.
The equipment is all Nema 4x and everything is dry inside of the enclosure.
The reason I am/was trying to stay away from the touch screen or ribbon switch is wet hands with gooey milk replacer on them touching things probably would not be good for durability and they are utilizing them a lot everyday. Another point to note is there is language also which is another reason why I am trying to go this way.
Will let you know what I find out and if you have any idea's feel free to share.
Learning is good!
My family dairies in Wi so I know the lovely environment you're talking about. I have C-mores getting splashed by milk and wiped down, sitting in parlors and calf processing areas. I expect them to fail someday but at their price point, its fine.
I would still use the HMI for display(it is Nema 4 with the gasket), but possibly add physical buttons for the most used features. You'll need to use a timer in the PLC to slow down the update rate of the gallons value when they are adjusting it with that switch. I don't know what kind of resolution you need, but have it add 5 gallons every 500ms or something similar.
The CMore panels are IP65 and NEMA4/4X rated, which is dust-tight and allows for spraying directly from any angle with low-pressure water. So technically they should work fine in your application if installed correctly.
The only thing I would worry about is how high pressure are your washdowns? As MikeRector said, you may end up needing to mount the CMore in a polycarbonate box on its own and basically used as a display rather than an HMI (displaying set point and current fill level and whether the process is running or not). I think using a pair of push buttons as discrete up/down buttons would work well in this instead of a potentiometer. The Schmersal Harsh Duty 22mm are IP69K rated and so would have no problem in a full washdown environment.