Per default all devices get the same I2C defive address. As soon as the device is connected you should set up a new address for them. The following commands will set the device [0x2f] to address 0x31 and save this setting in the EPROM.
i2cset -y 1 0x2f 0x22 0x31
i2cset -y 1 0x2f 0x21 0x02
The following registers are used:
0x00 .. 0x08 INPUT and OUTPUT registers dependung on device