If desired the DIU may be configured to monitor either one of two leads
(RTS or DTR) which typically are asserted by the DTE. When this lead is not asserted
an alarm is then reported. In this way the DIU can be relied upon to report if one of
these conditions occurs:
DTE is powered down
DTE cable is disconnected
DTE goes offline
Use G1 to select the LOS lead for port 1.
Use G2 to select for port 2.