switch bounce

[Ajb181]

hi Im using a usb6008 to switch a relay but i seam to get a bounce effect when it switchs hi. can any one help

thanks

[Joe_H]

I would say it is the relay and not the card. What you could do to test to see if it is the relay or the card is to put 5 volts from a power supply onto the same pin (with the card disconnected) where the card used to be and see if you see the same results. I personally have not seen this card have a switch bounce effect, however this is common to some types of relays. If you do not have a power supply you might could use the 5V output from the card.

[Ajb181]

i have tested it and the switch doesnt bounce with just 5Volts

[mikeporter]

What kind of relays are you switching? If you can use ones that have "wetted" contacts that should handle most or all of the contact bounce. Also when you say that the bounce occurs when "it switches hi" do you mean when the relay is energizing (closing) or deenergizing (opening)?

Mike..

[Ajb181]

when the relay is switch on (closed). the bounce sounds software related as it a little delayed. how should the Assistant be set up. Refr picture

[mikeporter]

In terms of how to set up the Assistant, I'm afraid I can't help as I dont't use it. I've found that it is easier to start with an example VI that is shipped with LV and tweak it to do what I need. How are you detecting this contact bounce? I would be very surprised to see this be a software issue because contact bounce is a physical process. If you tell an output to go high and it doesn't right away, that is a bug. (Of course there could be noise issues or bad connections).

Mike...

[johnsold]

The USB-6008 is rated to handle 8.5 mA on the digital outputs. Does your relay draw more than that? I do not know how the digital output would behave under a moderate overload, but it might explain what you are observing. If your relay does require more current, you will need to add an amplifier or a low coil current relay as a pilot relay.

Lynn