NOLAND ENGINEERING "DX28" NMEA 0183 Dual Expander

The DX28 Expander is a 2-channel signal splitter/amplifier for NMEA 0183 data signal distribution. It can be configured as one 1-in x 8-out expander, two 1-in x 4-out expanders, or an auto-switching expander. The two inputs are completely independent and can operate at the same or different baud rates up to 38,400. The selectable Auto-switching feature enables automatic switchover to the AUXILIARY input when signal is lost from the PRIMARY input. A bicolor (green/red) status LED on each input shows data activity and a third LED (yellow) provides “overcurrent” fault indication

Each input drives four independent RS-422 outputs. The inputs use differential detectors, which are isolated from Power and Ground. The outputs are independent so that shorting one output does not affect the others. The two channels (PRIMARY & AUXILIARY) are identical and completely independent of each other except in “Autoswitch” mode. For a single 8-way expander, the two inputs are strapped together. In "Autoswitch" mode a loss of PRIMARY data for 3 seconds automatically switches to the AUXILIARY input. When the PRIMARY signal returns, the DX28 immediately switches back to it.