A small class I wrote to easily turn on and off the relay on a PiFace for the Raspberry Pi.

pifacerelayclass.py

import time
import piface.pfio as pfio

pfio.init()


# A class to controll the relay
class Bpress:
    def relayon(self):
        pfio.digital_write(1,1)
        print "Turning on relay!"
        while True:
            if pfio.digital_read(0) == 0:
                return

    def relayoff(self):
        pfio.digital_write(1,0)
        print "Turning off relay!"
        while True:
            if pfio.digital_read(1) == 0:
                return


piface = Bpress()

# Relay Test
piface.relayon()
time.sleep(3)
piface.relayoff()