Using LabView to control solenoid valve in gas system.

[pubodee]

Hello,

First, I new for LabView program don't know much about this program except it can connect and control instrument.

Second, My advisor want to move the manual system into automatic system which control through LabView by using

the temperature and pressure is a trigger for open/close the solenoid valve. (starting with 2 2-way and 1 3-way solenoid valve)

Third, this system start from zero; right now i've a trial version of LabView 2010 for testing, and temperature/pressure sensor in RS323

which easily to connect to LabView.

The problem is what module or equipment for connect solenoid valve with LabView?

thk.

[johnsold]

That depends on the characteristics of the solenoid valves.  

The way to approach a project like this is to develop a specifications document.  It will include everything the system is required to do (and should probably have an optional list of things which someone would LIKE to do as well).  It will list the equipment including the power requirements (for the valve coils for example). It will list the inputs from users or other devices (such as your pressures and temperatures). It will list outputs (valve actuations, data displayed to users, data saved to files,...). It will describe the functional and timing relationships between inputs and outputs.

From such a requirements document you can begin to determine how to put your system together.  What parts should be done in hardware and what should be done in software.  This is the system design or system architecture.

Then you proceed to more detailed design such as selecting I/O devices for the interface between the computer and the valve, or between the computer and the pressures and temperatures to be measured.  For your valves you may choose a standard DAQ device with a digital output port and some external devices like transistors or solid state relays to switch the valves or some company may offer a valve controller which uses USB or Ethernet to communicate with the computer.

While doing this you should look at the on-line tutorials for LabVIEW to begin to learn about it.

Lynn

[pubodee]

Thank.

This is because i never work with solenoid valve before and it expensive to buy for testing. So, i'm not sure it can connect and control through LabView.

Nonetheless, i'll find how to operate the solenoid valve through LabView.

Due to this system is gas system, so i use only pressure and temperature value to turn valve open/close at a given pressure or temperature.

When system running i collect data only pressure, temperature, time, valve open/close time. (for present time)

For this system running at 150psi but the expansion is 1500-2000psi then i must select valve that can withstand higher pressure before other

specification such as valve actuation, power requirement ...

About part in software and hardware, my planed is use LabView as a software that connect hardware through RS323 and USB DAQ as following:

-temp/pressure sensor via RS323 (already done)

-solenoid valve via USB DAQ (it's a problem)

So, to control solenoid valve in my system it can use only standard DAQ connect with solenoid valve. That's great!

Thank you.

[tinnitus]

Rs 323 , what is it ?

[johnsold]

You must select a valve which meets your pressure and flow requirements.  Then you can compare the power requirements for the valve coil to the power output capability of the various DAQ devices available.  It is very likely that the valve will require much more power than the DAQ device can provide.  I this case you will need to install some external circuitry between the DAQ and the coil of the valve to boost the power to the level required.

Lynn

[pubodee]

Sorry, RS232

[pubodee]

thank, i know that this kind of solenoid valve need external power because normal DAQ can't provide enough power to operate.

Normally, ASCO valve needed 4, 120, 240, 480 volts for AC, 60 Hz and 6, 12, 24, 120, 240 volts, DC.

So, right now i think the problem is solenoid valve itself because mostly in market they have 3 wire (red, black, green?)

red, black definitely is power cable(+/-), green must be control cable but how this one wire communicate with LabView?

[johnsold · Accepted solution]

I think the green wire on ASCO solenoids is earth ground.  Red and black are for power.  If you use an AC solenoid, you can switch it with a solid state relay.  Most solid state relays require 3-32 VDC at a few mA for control and the control is isolated from the power circuit.  There are DAQ devices with digital outputs which can drive the solid state relay input.

Lynn

[pubodee]

that help me a lot johnsold.

Thank.

[VeeJay]

Hi Lynn,

It's me with a different issue 🙂

Is USB 6008 good enough to control a 120VAC 1/3 HP motor using digital out using D2425 Crydom SSR?

http://forums.ni.com/t5/Multifunction-DAQ/Error-50405-USB-6008-OEM/td-p/1530316\

VJ