Vacuum Solenoid Valve Control

[rlinklater]

Excuse me as I am fairly new to Labview and my background is in Computer Science, so hardware is not my forte.

I designed a Labview Program that will open and close a valve to a vacuum pump to simulate an object leaving earth's atmosphere. I need to figure out if opening and closing this valve would need to be analog or digital and how to determine if a solenoid is compatible with LabView.

The engineer suggests a valve that alternates opening and closing rather than opening and closing partially, which leads me to believe that it would be analog input.

[Henrik_Volkers]

Before you start to write a program, you need to know what is and how you want to solve the physical part 🙂

It could be as simple as turn a digital signal on for a certain time to create vacuum for a cretain time ... if the hardware is designed to do the rest 😉

But could be much envolved, like reading some sensors, have one ore more control loops, .. run various ramps in defined tolerances ... 

A common technique to create a mean value between 0 and 1 is pulse modulation. Usually the actors are cheaper but the price is a ripple and mechanical fatique, if involved.

Since DAQ IO is quite cheap, your problem seems to be physical part.

[rlinklater]

Yes my problem is the physical part. I've been looking at parts online (mcmaster-carr) and the part that I am confused about is how to determine if they'd work with the DAQ. Are there key words or something? Is the cable used to send the signal a standard? Do I need some sort of converter? They never seem to give information on the electronic aspect apart from it's closed when it's off and open when it's on. 

We already have all the sensors in place, so far the company has just had a guy reading the data on the screen and opening and closing the valve as needed. So I plan to do the same with the automated valve and optimize from there.

[MrJackHamilton]

There are 4 elements you need to make LabVIEW operate a solenoid valve.

1. LabVIEW DAQ device can drive a digital output that is 5VDC.

2. You need a 5VDC DC Relay that when is get the DAQ digital signal - it will open or close the relay.

3. You wire the solenoid + lines thru the relay - when the relay closes, the + Power goes thru and the solenoid/value operates.

4. You need a power supply that is at the operating voltage of the solenoid. [DC or AC - depends on your vacuum solenoid]

2. Here is a link to a 5VDC actuated relay - that can let 30VDC or even 250AC power to run thru it.

https://www.amazon.com/Tolako-Arduino-Indicator-Channel-Official/dp/B00VRUAHLE/ref=sr_1_3?ie=UTF8&qi...

The wiring is the next bit, but there is lots of content online on how to do this.

[Henrik_Volkers]

So first thing you need is a list of the IO requirements:

Solenoids: Voltage (24V?) and current ..

Ananlog outputs: voltage range , current range

Inputs:

Digital: voltage level

Ananolg: current or voltage (range)

collect all datasheets of the devices you want to connect. Have them ready when you call NI

I would go with the C-series modules .. you get them ready for most industral IO and sensors.

(no need for 5V relays if you already have  valves with a powersupply .. , there are C-series relay boards or, what I would choose, 24V DO boards to switch valves) 

Seems that it could be done with one simple multi IO USB device, however  you would need to buffer /adapt the IOs to your needs and you mentioned that you're more at the software side 😉

[rlinklater]

Here are the specifications for the valve. I've been told we need a relay, but I don't know much more than that. And I'm having difficulty finding out exactly what kind of relay (I know nothing about them)

[MrJackHamilton]

Ok, Thanks for the spec sheet.

That's a 24 volts DC relay. 

How to figure out what relay you need:

1. There are 2 sides to a relay

     A. The 'control' side - what voltage 'triggers' it to open/close.

     B. The 'power' side - what voltage is 'flowing thru' to operate your thingy.

For you:

Relay: McMaster Carr: 7456K61 [I hope its' not zero-crossing, it does not say it is, so it will work for DC]

A = 5VDC, this means an inexpensive NI-6009 would activate the relay.

B = 24VDC: McMaster Carr: 7009K18  [Although a Meanwell from Amazon is way cheaper, get at least a 2 Amp 24VDC supply, the valve is drawing 0.8 amps]

I am not sure if your budget sensitive, Amazon has the PS and relays too.

Once you get everything - wiring it is pretty straight forward...assuming you have wire cutting and strippers?

Regards

Jack Hamilton

[Henrik_Volkers]

There is no need for an additional relay!

(and switching coils with a relay without snubbers is prone for failures due to contact arcing, a solid state solution with a freewheeling diode , just like the NI9474/8 )

Do you already have LabVIEW controlable hardware or do you need to buy some new stuff?

If you need new IO hardware, just choose the right C-modules, wire them to your sensors and actors and start coding 🙂

SInce the valve is already operating, I assume a 24V powersupply is already there 😉

[MrJackHamilton]

Henrik,

You've not looked at the valve specifications, and are not recommending a correct working solution. 

The value is a solenoid, (see the spec sheet) at 24VDC drawing up to 0.84 amp of current.

The NI9474 device you are recommending is a 'Digital' module and not a relay module. It does not have the ability to pass 'current' thru it to power the vacuum solenoid. Digital modules do not output significant current to 'power' things. They are design to 'trigger'. The Digital module will either not work at all, or burn up from the current draw.

That said, the price of the module your are recommending is $375 and it still needs a cDAQ or cRIO chassis to function, which is additional cost of at least + $1,200. So I am not sure what is the problem of the option of a $200 USB-DAQ, a $100 PS and a $50 Relay. I am offering approximately $500 total solution.

I've done quite a bit to vacuum system and gas control using NI hardware. So I am not speaking out of my hat here.

Regards

Jack

[Henrik_Volkers]

Both DO moduls drive or sink 1A (or more, see spec) 😄  , however adding a freewheeling diode (best at the valve) seems appropriate.

Concerning costs..  from material one migth gain (housing ??) if your own time doesn't cost much 😉

That's why I asked what is alrady available ..

there is always a cheaper solution (Arduinoclone and relay shield, custom driver ... <50$?? even less if you heat the solder iron, an optofet at the handshake line of a COMport) , I had the impression that the thread starter is more a software guy ...

And I bet the appetite will grow, so some industrial sensors will be wanted to be added 😉