Owner`s manual

40
  ###
   
When information is received by a Telplex terminal port, the data is
stored in a receive buffer and is subsequently transmitted to the
remote unit through the composite port. If the receive buffer fills, the
local Telplex will make the terminal port's CTS line false (negative
voltage), signaling that it cannot receive more data. When the buffer
empties to the point where the port can accept more data, the local
Telplex will make the terminal port's CTS line true (positive voltage),
signaling that it can accept more data.
The local Telplex will also make the CTS line false for a terminal port
if the transmit buffer of the designated remote terminal port fills.
   
When the Telplex transmits data out of a terminal port, the unit will
expect to see a false (negative voltage) on the DTR line if the terminal
device is unable to accept data. When the terminal device is ready to
accept data, the Telplex will expect to see a true (positive voltage) on
the DTR line.
If the DTR line is false on a local terminal port, the transmit buffer for
that port will begin to fill. If the transmit buffer fills, the local unit will
signal the remote unit to make the CTS line false on the designated
remote terminal port.
If XON/XOFF handshaking is enabled in the transmit data direction,
the Telplex will still check the state of the DTR line when transmitting
data out of a particular terminal port. By leaving the DTR line
disconnected, the DTR line is always enabled.