03-08-2012 01:28 PM
I need to use labview to operate an air compressor which is hooked up to a piston-cylinder assembly to produce a desired force. I have a NI PCI 6225 card, with the required cables and 2 connector blocks. What kind of pump should I be looking for? Do I require anything other than the mentioned items?
Any help would be greatly appreciated!
03-09-2012 10:14 AM
First, how do you expect to "operate an air compressor" to produce the specified force? Compressors typically run full speed until the pressure in a reservoir reaches a pressure threshold and then shut down. When the pressure drops below some lower threshold, the compressor is turned on again. The difference in pressures between the two thresholds is often 20% to 50% of the gauge pressure or larger. This would probably produce too much variation in your force.
Second, some compressors cannot be turned back on immediately after being turned off. This would put a limit on how close you could make the two thresholds.
Third, the rate of change of pressure in the system depends on the volume of the system (which probably is at least somewhat variable), the pressure/flow characteristics of the compressor, and the amount of air being removed from the system.
Fourth, the compressor power cannot be switched directly by the PCI-6225. What kind of controller will you be using?
<Lecture Mode = On> Start by establishing the system performance parameters. What is the required pressure range for the cylinder? How fast will the pressure be required to change? How much flow is required to change the pressure? What are the allowable error limits on pressure? How much and how fast will the external load on the cyclinder change? What safety features are required? What inputs do users provide to the system while it is operating? What information does the system provide to users? What power sources are available?
Other information may be required but this gives you the idea.
After you have the system performance requirements, then you can begin to design the system. Select one or more possible configurations. Evaluate which configuration(s) will best meet the requirements. Then begin the detailed design of the system components.
<Lecture Mode = Off>
03-09-2012 01:21 PM
Thanks Lynn for your guidance, I'll begin gathering more data on the project parameters. The thing is I was just plunged into this project without any briefing, just the final result.
Thanks again, I'll be back with more specific questions
03-09-2012 02:41 PM
A correction to my earlier query, I need to know how to wire the connector block to accept up to 10V and output the same. The objective is to control the valve using labview via the NI PCI 6225. A schematic would be great
03-09-2012 04:00 PM
Do you have the manuals for the PCI-6225 and SCB-68? Those are the best places to start on the wiring.
I think you still have too many things undefined to be ready to draw a schematic. Even if I were willing to do you project for you, I definitely do not have enough information about what you are trying to do to draw a schematic.
What does the "up to 10 V" signal represent? Presuming that you will be measuring the voltage with the Analog Input channels, have you defined which channel will be connected to that signal? Similarly for the output, which AO channel will you use? What is the load for the output signal? Can the AO channel drive it or do you need a buffer?