usb I/O hardware ???

[metallifredd]

I want to control a relay from labview and am looking for a I/O hardware (usb) to connect to my pc.

I looked at the lowcost usb multifuncional daq device from NI (6009) but I dont think that it could control even a very small relay.

I need the same device but with a little better ratings for controlling a relay. isolated inputs is also preferable. I also looked at the ADAM 4050 modules from advantech but it I could not find the usb model in my local stores...only the rs232 was available

Anyone know ?? please.

regards Fredrik

[dpacaba]

Hello Fredrik:

The USB-6009 has 12 Digital I/O lines. So if your relays have coil voltages of 5VDC, then the USB-6009 can control it. Or if you want, you can amplify the signal to control better relays.
I hope this helps. 😉

[Buechsenschuetz]

I could not find maximum ratings for output current in open drain mode but it seems that the current should be limited to 8.5mA. Actually only small relays can be driven with such a small amount of current. You can simply add any open-collector driver ICs such as the ULN2803 (there are many similar drivers) to speed up current up to 80mA or so. If you want to drive relays with higher voltage rating I would recommend using a PhotoMOS optical relay such as the AQV212 from Matsushita. They will work with a few mA input diode current (330 ohms is a practical current limiting resistor value) and can drive up to 50V at 100mA.

When connecting relays or solenoids to a semiconductor switch don't forget the snubber diode connected in reverse direction in parallel with the coil.

[Jimmie_A.]

Hello Fredrik!

Please call National Instruments in Sweden (telephone number 08-587 895 00) and they will be able to help you out. They can answer all your questions so you can get the USB hardware best suited for your application.

Regards,
Jimmie A.
Applications Engineer, National Instruments