Instruction manual

36 Equinox MEGAPORT Hardware Reference Manual
CS Port Full Modem Control Wiring
As discussed above, MEGAPORT CS ports regularly provide two
modem control signals per port (i.e. CNTL OUT and CNTL IN),
which may be used for either modem supervision (DTR/DCD) or
hardware flow control (RTS/CTS), under software control.
The combination of various software flags and some special signal
rerouting (the “borrowing” of two control signals from a neighboring
“donor” port) provides the additional two signals. Up to one half of
the CS ports on a board can thus be used for devices requiring full
modem control, leaving the remaining ports available for use with
terminals and printers.
Figure 3-16 shows the wiring needed to connect a donor port’s
control signals to a full modem control recipient port. Equinox offers
several full modem control wiring accessories which provide both
sets of signals. They are outlined below.
Figure 3-16. Full modem control signal rerouting