Connects to a PC or Laptop using our USB Cable or to any other host which incorporates an RS-232 serial port. Stack multiple cards together on the same port. Provides 8 digital inputs for dry contacts, TTL level signals, or NPN type sensors, and 2 open-collector digital outputs for control. The wide range digital inputs not only provide power for dry contacts, but in many cases can be wired directly to contacts which have external voltages already present. The digital outputs are robust enough to directly control the on/off states of other electrical equipment of up to a full ampere in current.