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20 Sun PCI High Speed Quad Port Serial Interface Adapter User’s Guide • May 2010
If the CTS signal drops before the frame transmission is complete, the frame is
discarded and the abort error statistic is incremented. If the transmission underruns,
an abort sequence is not sent and the frame is silently discarded. The RTS signal
remains asserted until the data transmission is complete.
IBM Half-Duplex Mode
Half-duplex is a submode of the IBM mode (
mode=ibm-hdx
). Half-duplex mode
operates in the same manner as full-duplex mode except that transmission cannot
occur while receiving, and vice-versa. When a transmission is completed, the RTS
signal is dropped. Dropping the RTS signal tells the remote station to begin
transmitting if it is ready to.
IBM MultiPoint Mode
In a multipoint configuration (
mode=ibm-mpt)
, more than two stations share a link.
This configuration is accomplished by designating one station as a primary station
and the rest as secondary stations. In this mode, the port acts as a secondary station.
The primary station arbitrates traffic on the link by polling the secondary stations, to
see if they are ready to transmit.
If a secondary station has data to transmit, it will raise its RTS signal and check for
CTS signals. When a CTS signal comes up the station may begin transmitting,
following the same rules for RTS and CTS signals used in half-duplex mode. When
the transmission is complete the secondary drops the RTS signal, which enables
another station to respond to a poll and begin transmitting. The RTS signal cannot be
dropped until the transmission is complete.
hsip_loop
Utility
The
hsip_loop
utility is high-speed, synchronous, serial loopback test program for
high-speed serial interface. The utility performs several loopback tests that exercise
the components of a serial communications link. See the
hsip_loop
(1M) man page
for more information.