Devantech

This Devantech USB relay board provides 6 voltage-free contact relay outputs with a current rating of up to 16A each. Powered and controlled from any standard USB bus.

Powered and Controlled from the USB bus.

Relays - 4 with integrated snubbing of the normally open terminals
Power - Powered from standard USB bus 
Control interface - USB with a mini B connector
Relay current - Up to 16Amp @24vdc or 250vac 
Connections - Screw Terminals for N/O N/C and Common contacts.