7
Switch 3 and Switch 4:
Switch 3 turns ON, or OFF, the
gating of CTS by the DET2 data.
Normally, CTS is triggered by RTS
and in a typical “Polling” application
the FLD2SA will need no further data
routing.
However, for other applications, it
may be necessary to turn CTS off
when data is being transmitted from
an upstream FLD2. This prevents
data collisions in the downstream
fiber path.
The following waveform
shows how this works:
Normally, when RTS is
asserted, CTS is asserted
and the controller is
enabled to transmit.