4RF Aprisa XE User Manual - page 137
Configuring the Traffic Interfaces | 135
Aprisa XE User Manual
HSS Handshaking and Clocking Modes
This section provides detailed information on selecting the recommended HSS handshaking and clocking
modes for the HSS interface card (see ‘HSS port settings’ on page 133).
HSS Handshaking and Control Line Function
HSS X.21 Compatibility
In general X.21 usage, the C and I wires function as handshaking lines analogous to RTS/CTS handshakes.
For switched carrier applications, the I wire is used to emulate carrier indications (DCD) function.
HSS RTS / CTS Mode
Set the RTS CTS Mode as required according to the table below. This field controls the state of the
outgoing interface control line.
When the HSS interface is DCE, the outgoing control line is CTS.
When the HSS interface is DTE, the outgoing control line is RTS.
RTS CTS Mode
HSS as a DCE
HSS as a DTE
Comment
Always Off
CTS driven to off state
RTS driven to off state
Always On
CTS driven to on state
RTS driven to on state
Follows
Carrier
CTS follows the state of
the RF link
RTS follows the state
of the RF link
To follow carrier is to indicate
the state of synchronization of
the RF link
Follows
Carrier +
Remote
RTS/CTS
CTS follows the state of
the RF link and the
remote terminal RTS
input control line if the
remote is a DCE. If the
remote HSS is a DTE,
then CTS follows the
state of the RF link and
the remote HSS CTS
input.
RTS follows the state
of the RF link and the
remote terminal RTS
input control line. The
remote HSS can only be
a DCE.
Control line pass-through mode
where RTS and CTS are carried
over the link from end to end.
The carrier (as above) plus the
remote terminal input control
line must be present to output
the local control line signal.
The HSS Control bit in the Cross
Connections application must
be set for the remote signalling
to operate.
Follows
Carrier +
Remote DCD
CTS follows the state of
the RF link if the remote
HSS is a DCE. If the
remote HSS is a DTE,
then CTS follows the
state of the RF link and
the remote HSS DCD
input control line.
This setting is only applicable
when the local HSS card in the
local terminal is a DCE. The HSS
Control bit in the Cross
Connections application must
be set for the remote signalling
to operate.