i want to transmit a square pulse through USB port, is it possible?? if not then what is the best way to do that, preferable is with serial then parallel, and its compatibility with vista,XP,and @))7 windows

[sanghi]

hi froends

i want to transmit a square pulse using lab-view, please help how to do that, the preference  will be USB,SERIAL, Parallel ports, it it must be compatible with all the os versions, like 2007 windows, vista,XP and other.

please help..................

[Lucither]

Hi Sanghi,

What are the required paremeters of the pulse?? frequency, duty cyle, voltage's etc....

Rgs,

Lucither.

[sanghi]

i just want to triger some harware from that pulse, i think voltage will do with 50% duty cycle with any basic frequency...

[Lucither]

Hi,

What i meant by 'Voltage's' was what value of voltage is required. I know it will be a voltage.

I have used the parallel port in the past to implement an i2c driver using the 'In Port' 'Out Port' vi's found on the 'Connectivity' - 'Port IO' Pallete . This worked well but i think im right in saying that there may be an issue with this in windows 7?? Hopefully someone can clarify that or not.

The output voltage of the parallel port is 5v. Care must be taken though not to damage the port, i cant remember off the top of my head the exact current capacity but i know its not much. What is the input impedance of the device you want to drive. Would be best really to buffer the output with some circuitry. All i used for my circuit was a diode that only allowed the output to source voltage and not sink but i was only talking to an i2c device which drew hardly any current.

Try and give as much info as possible. Really not enough information to fully help.

Rgs,

Lucither

[Coq_Rouge]

Why do you not tell exact what you are trying to do. Any detail obvious to you may not be obvious to us. So please give us all your specs. That will work much faster. Compared to then we must drag every detail out of you.

[smercurio_fc]

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Lucither wrote: 

I have used the parallel port in the past to implement an i2c driver using the 'In Port' 'Out Port' vi's found on the 'Connectivity' - 'Port IO' Pallete . This worked well but i think im right in saying that there may be an issue with this in windows 7?? Hopefully someone can clarify that or not.

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There is decreased functionality with those VIs in recent Windows versions due to changes in what Microsoft allows users to do with hardware. You can see this article for more information.

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Lucither wrote:

The output voltage of the parallel port is 5v.

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That's only true for older computers. Most computers nowadays are 3.3V for the parallel port, assuming they even have one.

For original question:  This kind of question comes up a lot (just do a search on, say, using the parallel port as a digital I/O). Bear in mind that the serial port, parallel port, and USB ports are not designed to be DAQ devices. They're communication devices. While you can use them to do some simple stuff, this is extremely limited due to the fact that whatever you do will be software controlled, and they cannot drive much (they're low current, by design). Thus, you will not be able to guarantee any kind of duty cycle or frequency.

[sanghi]

OK I WANT TO DRIVE A RELAY.

SUGGEST SOMETHING 

[Intaris]

What switching power and voltage does your relay require?

Otherwise I suggest buying a device with TTL outputs.

Shane.

[Coq_Rouge]

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sanghi wrote:

OK I WANT TO DRIVE A RELAY.

SUGGEST SOMETHING 

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It is no reason to start writing in caps..... In order to help we need some details. That is all. If you only need to control one relay, and that relay has a somewhat static operation. You can use both serial and the parallel port. But in both cases need to boost the output current. This can be done by transistor and some external power supply. If you try drive the relay directly from the PC you may kill output device, or in worst case the mother board.

[Ray.R]

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sanghi wrote:

OK I WANT TO DRIVE A RELAY.

SUGGEST SOMETHING 

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Calm down!

People can't read your mind.  If you want help, repsect those who contribute their time for free to try to help you.

Put yourself in our shoes.  If I tell you I want to build a rocket, what information would you give me?  You would need to know if it's for a hobby, something bigger, carries a payload, carries living organism, how far does it go, where does it land (if at all), etc...  

First of all, we still don't know what you want to do with this relay.  Using a computer to generate is series of pulses is not usually the best way.  What is the frequency of the pulses that you want to transmit?  And why do you want to use a relay?  What are you driving?  Can the relay that you are using fast enough to follow the pulse train that you'll be sending?

Provide information, ask questions politely and people will help you.