valve actuation

[Cheebers]

Hello,

I have used Labview before but I dont consider myself to be an expert. I am trying to actuate two solenoid valves using the USB 6525 DAQ. The valves need 12Vdc for 20-30ms to actuate, once switched no additional power is required to hold the valve in position. I want to use this DAQ becuase it has internal SS relays that I want to control using LabView. I want the Labview block Diagram to let the user choose when to open and close the relay using miliseconds( this is very important). Here are my questions:

1)How do I connect the valves to the USB 6525 DAQ with the external power source.(just to make sure)

2) I need help creating the block diagram, I dont know where to start

Any help will be greatly appreciated, I have been trying to solve this problem for more than a week.

[Dennis_Knutson]

The relays are opened/closed with a digital write command. You can use the lower level DAQmx functions or the DAQ Assistant. I would recomend you check out Getting Started with NI-DAQmx.

As far as timing, the device is software timed and unless you use a real-time OS, you are going to have considerable jitter in any timing function (i.e. Delay, Wait (ms), etc) you use. You can set the write time to 30 msec and it won't be any less than that but it could be 10's of ms greater.

[Henrik_Volkers]

The USB 6525 Manual states:

Switching rate (90% duty cycle) ............5 operations per second

[Cheebers]

Thanks.....lets me try it out. I'll get back to you soon.

[Cheebers]

 I went over the Getting started with NI-DAQmx and it was very helpful. I was able to send simple analog signals to one of my DAQs and MAX is very easy to use and helpful when testing my hardware. But Im still confused on how to control the relays on my USB 6525. You mention that the relays are opened/closed with a digital write command, but is that an out put signal from labbview to the DAQ? Or do I need another DAQ to send a digital signal to the USB 6525?Which lowere level DAQmx function should I use to send the write command?

[Dennis_Knutson]

You can use the DAQ Assistant and select Generate Signals>Digital Output or use the DAQmx Write and change the polymorphic type to one of the digital output types. You change types by right clicking on the function and selecting 'Select Type'.

No, you do not need another DAQ card.

[Cheebers]

Thanks! Its works. I used an LED Light and connected it to the DAQ and I managed to turn it off and on using the SS relay. However I could only do it on demand. I would like to set a time to turn off and on ones I click Run? What are my options?

[Cheebers]

I guess my question was too vague. Ill try again. I used an example "write digital channel VI" that was in Labview, and I was able to control the SS relay in my DAQ. I could have also used the DAQ assist but I feel more comfortable with DAQmx (I could see what’s happening). When I run the VI, In the front panel, I have to manually click on the virtual button to send the signal to the SS relay. This is fine, but I would like Labview to read a Binary code to control the relays. Using the block diagram that I currently have and with a binary text file, How can I make LabView read a binary code and turn it to digital to control my valves. I have attached an image of the block diagram and the binary text file that I want to read. The reason I ask this is because I have seen it done before. Thanks

[Dennis_Knutson]

You can use something as basic as the Read From Spreadsheet File or the Read From Text File. Converting from a 0,1 array is pretty basic as well.

Message Edited by Dennis Knutson on 12-08-2009 01:08 PM

[Cheebers]

Im sorry im still confused. Im really trying to learn the software   . How do I sync the time to the binary code? Is there any examples you might suggest looking at? Im learning as we speak. I also added an attachment