I/O expanders may also have interrupt pins that are asserted LOW when an external change on an I/O pin is detected. For totem-pole devices, the port pin must have been configured as an input, and for devices that are interrupt-maskable, the port must not be masked. For quasi bi-directional or open drain I/O, a write sequence to the device does not generate an Interrupt. It is important to note that Input values are not latched, which means that the interrupt is de-asserted as soon as the input that generated the Interrupt goes back to its previous logic value. The I-O expander is reset in many ways. One way is that an internal POR resets the device when VDD is first applied. Additionally, devices with a hardware reset pin may be reset by momentarily holding the pin low or, finally, a software reset is achieved when a specific formatted I²C bus command is sent to the device to which the device responds by resetting to its power-up state. Multiple I/O expanders can be used on the same I²C bus by setting the device address. Up to 112 devices are available.