The NPort 6600 provides adjustable termination, pull high, and pull low resistors for RS-485 communication. In some critical environments, termination resistors may be needed to prevent the reflection of serial signals. Pull high and pull low resistors may also need adjustment so the electrical signal is not corrupted. Since no set of resistor values works for every environment, the NPort 6600 allows manual adjustment of the resistor values for each serial port, using built-in DIP switches.