The HR-4P is a programmable RS-232 device designed for control & automation of a Projector, LCD or any other device with serial or IR port. The unit has 4 configurable I/O lines that can be defined individually to act as input or output. When configured as input, they sense contact closures or Voltage levels (user defined as pull-up or pull-down). Upon detecting "Low-to-High" or "High-to-Low" transitions the unit can issue programmed Serial RS-232 Commands, as well as IR commands for controlling infrared equipped devices. When configured as output, the I/O pin can be commanded to short to ground (open collector and high voltage open circuit tolerant) perfect for controlling external relays.