How to control solenoid valves from computer

[ImGoodMan]

Dear all,

I need to control 4 solenoid valves (24V, 4W) from a personal computer, say, to open the valves in turn every 5 seconds and open each for 0.5 s.

I am looking for an "interface card" between the computer and the solenoid vavlues, based on USB, RS232, or GPIB. Moreover, I prefer to program with SCPI in Matlab.

Any hints will be highly appreciated.

[SnowMule]

sounds like you need:
-a daq/dio, usb-6501 will do
-24v power supply
-relays
-relay driver (uln2003)

[AnalogKid2DigitalMan]

Skip the relays, use the ULN2003 to drive the solenoids directly!

-AK2DM

[K C]

Don't forget the protection diode to keep he ULN alive.

Kees

[AnalogKid2DigitalMan]

They have the diodes included already in their die.

http://www.ti.com/lit/ds/symlink/uln2003a.pdf

-AK2DM

[ImGoodMan]

Your people are really helpful.

I saw some threads in which NI 9472 was used to control the solenoid valves directly. I called my local NI support and the guy told me that NI 9472 did not support SCPI. So if I turn to use Labview instead of SCPI, the hardware part will be simpler, right?

I have to control a mass flow controller (MFC) with RS485 (see below) at the same time, and also do not konw how to realize. Help, please.

--

Best,

ImGoodMan

[zakzackzachary]

Hi all, 

Sorry to revive an old thread, but it's very similar to what I'm trying to do.

I'm looking at purchasing a 24VDC solenoid valve and then controlling it via PC in order to turn it on/off to generate a pulse of water. 

So I'm trying to piece together what I'd need for this. I have:

• LabView program
• USB-6501 DAQ

I'm thinking of picking up one of these solenoid valves, which I'm hoping have some sort of +/-/signal interface for control, but I need to look into it:

• ASCO
• McMaster-Carr

Finally it looks like I'll need:

• 24VDC power supply
• ULN2003 transistor array (?)

Those last two bullets are where it gets foggy for me. I'm considering a 24VDC valve, so a 24VDC power supply makes sense, but I can't seem to find any. And I'm not entirely sure what the transistor array is for. 

It seems like a relatively simple set up, I just need to power the valve, and then either send a control signal to turn the valve on/off or maybe just control when the valve receives power from the power supply. Right? 

Any help would be great, thanks in advance!

[Buechsenschuetz]

24VDC power supplies should be easy to locate. You can even buy "wall transformers" with 24VDC/1A output off the shelf.

Usually a digital output of a PC system can handle 5VDC max and the current is limited to approx. 100mA in most cases. If your circuit runs on higher voltages and if you need more current to drive your device you need an interface which can handle these ratings on the output and can be driven with logic-level (TTL level) signals as they are supplied by the PC system. That's what this transistor array will do.

However, if you are not familiar with designing and building your own hardware, you can also buy ready-made interface devices. Look for "opto-isolators", most of them can be driven with TTL level signal and 24VDC output handling is very common.

[johnsold]

The USB-6501 can handle currents up to 8.5 mA at 0 or 5 V. The current requirements for the solenoid valves depend on which coil you choose. The 11.6 W coil will draw 483 mA at 24 V.  700 mA for the 16.8 W and over 1 A for the higher power coils.

The ULN2003 can handle up to 500 mA (but possibly not continuously, depending on package and drive). Multiple devices can be connected in parallel for higher currents but the current sharing is not perfect and some derating is necessary. The data sheet does not give any good guidelines for parallel operation. I would suggest no more than 300 to 350 mA per device. If you intend to operate this device in a multiple parallel mode, calculate the power dissipation and temperature limits carefully.

Lynn

[zakzackzachary]

Thanks both of you for your replies! I'm going to process that info and see what I can come up with.