Reports the polarity sense of each of the IR ports. These settings will also affect the IR routing system. The bits of P represent the 8 IR ports, IR0 being the LSB, IR7 the MSB. A "1" bit indicates that the input is active-low (when the  input goes to 0 Volts), a "0" bit indicates that the input is active-high (when the   input goes to 5 Volts). All ports are active-low by default so that they will work   correctly with the IR receiver modules. If you have some other low-speed serial device which is active-high (e.g. a Control-S input) that you would like to connect, you will want to change the polarity on that port. Be careful with this option - if you set the wrong polarity for a port, the Slink-e will be locked into a constant receive state and will become unresponsive.