Normally Closed Relay

[Neka]

Hi,

Is there anybody to tell me how I can connect my Labview program to my AC machine with a normally cloed relay.

My machine has 6 VAC and 500 mAM.

Regards,

Mehdi

[smercurio_fc]

Well, you don't really "connect" LabVIEW to your machine. You connect hardware to your machine, and you have LabVIEW control that hardware through some means. In your specific case are you trying to control your relay? What kind of relay is it? What kind of DAQ hardware do you have? If you have no DAQ hardware then what else have you got?

[Dennis_Knutson]

Is this the same thing you were asking here? Don't start a new thread for the same question. As explained in the other thread, you need to pick a relay and then some kind of data acquisition card to drive it. You could even use the parallel port or RS-232 port of the pc to drive a relay.

[smercurio_fc]

Thanks for spotting the double post, Dennis. For some reason I missed the original post.

[Neka]

Hi,

Thanks for answering.

Actually, I still dont have DAQ and dont know which type relay. There are a lot external board in NI, for my case if there is an external board with a realy which connect me to my machine it will be fantastic.

I dont know anybody had tried my case. There are a lot of posted question but they did not work for me (I think).

I really tried a lot I still dont know which NI external board (USB or  ...) will work for my case.

Please could anyone help me.....................

[Dennis_Knutson]

Any DAQ board with at least one digital output will work for you. The cheapest is the USB 6008. and as I mentioned, if that is all that you need, you can use the parallel port or RS-232 port of the pc.

[Neka]

Hi

Thanks.

I just found NI USB-9472.

Its signal level is 6 to 30 V and out put current 0.75 A.

Can I connect a realy by myself to the extrenal out of  NI USB-9472?

[Dennis_Knutson]

Sure you can use it. If you've read the manual, you'll know that you'll also need an external voltage supply as well.

With the 6008, you'll spend a lot less. All you need then is a relay that operates at 5 volts and some sort of current amplifier. There's a circuit here or use a ULN series relay driver. It's up to you - either spend more money on everything off the shelf or spend a lot less and do a breadbread circuit and a little soldering.

[Neka]

I really appreciate your help. I am a mechanical eng.. to engage with circuit maybe a little difficult.

If I am able, my question is: the relay which will be connected to USB-6008 will recive max 200 mA and voltage is 5 V.

You know better, does it consistant with my machine specification (6VAC and 500 mA)?

Does it work? or I have to put an amplifier? how can I connect an amplifier to your circuit?

If I do all of them is its cost less than UBS-9472?

[Dennis_Knutson]

You are comparing apples and oranges. The voltage and current required to turn a relay on or off has nothing to do with the signal you are passing through the contacts.

The 6008 is not capable of sourcing 200ma.

You should be able to do a cost comparison. Besides the 9472, you need some exteranl power supply. Besides the 6008, you need a couple of dollars worth of parts to drive the relay coil.