Solution:

FDF4SE LEDsThe FDF4SE LEDs indicate the activity on the MASTER Port of the unit.The flashing Transmit LED indicates data is being transmitted OUT of the Master port and is coming into the Fiber portsThe flashing Receive LED, indicates data is being received from the Master Port and is going OUT of the Fiber PortsThis seems the reverse of most of our other Serial to Fiber converters. The LEDs of the FDS4FE , work the opposite of the LEDs of the FDF4SE.The FDS4FE LEDs flash in accordance with the Fiber ports. The Transmit LED will flash when data is transmitted OUT the Fiber Port, and Receive LED will Flash when data is received FROM the fiber port.The FDS4FE functions more like the rest of our Fiber converters. Peter Fitzpatrick 7/28/11