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CHAPTER 5: Operation
5.3.6 T
HE
B
ROADCAST
-M
ODE
F
LOW
-C
ONTROL
O
PTION
When the master device is transmitting to all slave ports during Concentrate
and Broadcast Mode or Broadcast Only Mode, the Terminal Eliminator Plus
sends data to the slaves one byte at a time in “round robin” fashion
[consecutively from Port 1 to Port 4 (or 8)]. Each port receiving this
broadcast data can exercise independent flow control. The TEP provides the
option of either acknowledging or ignoring incoming flow control during
broadcasting. Position 3 of system switch SWF controls this option:
ON:
With position 3 ON, the Terminal Eliminator Plus will acknowledge
a port’s flow control signal. The TEP transmits the data from the master
console to each input port one byte at a time. If it encounters a port that is
configured for hardware flow control, and DTR/CTS is inactive, the TEP will
wait for the port to raise DTR/CTS before transmitting further data to
any
port. The console data received will be buffered. The same principle applies if
the TEP encounters a port that is configured for X-ON/X-OFF flow control. If
that port receives an X-OFF, the TEP will wait for the port to receive an X-ON
character before transmitting further data to
any
port.
OFF:
With position 3 OFF, the Terminal Eliminator Plus will bypass any
port that is exercising flow control. When the TEP encounters a port that
is configured for hardware (or software) flow control, and has dropped
DTR/CTS (or sent an X-OFF character), it will not transmit that byte to the
port. Instead, the TEP continues transmitting to the other ports in
consecutive order. When the buffered port raises DTR (or sends an X-ON
character), the TEP will resume data transmission to that port. Any bytes that
were
not
transmitted to the port are lost.
The setting of SWF position 3 only affects flow control during broadcasting.
It has no effect during Concentrate Only Mode or either Conversation mode.
5.3.7 T
HE
“B
ACK TO
C
ONCENTRATE
M
ODE
” T
IMEOUT
From the initialization menu, you can set and enable, or disable, a timeout
to exit from either of the Conversation modes or Broadcast Only Mode back
to the standard Concentrate mode. This timeout is useful when the TEP is
normally used in a Concentrate mode, and is only occasionally used in a
Conversation mode to send some data to a slave device. If you forget to exit
the conversation by sending the “Disconnect” or “Abort” commands (refer to
Sections 5.2.1 and 5.2.2
), this timeout will occur and take the TEP back to its
standard Concentrate mode so other slaves’ data can be transmitted to the
master device (possibly preventing the TEP’s internal buffer from overflowing
when attached slave devices don’t respond to flow-control requests).
