Q-Flex Satellite Modem Installation and Operating Handbook
13-2
13.2 Edit->Tx-Rx>Framing->Overhead Closed Screen
The
Edit->Tx-Rx->Framing->Overhead Closed
screen, shown in
Figure 13-2
controls the
overhead in Closed Network Plus ESC mode, allowing the high-rate asynchronous ESC
channel to be set up.
Figure 13-2 Edit->Tx-Rx->Framing->Overhead Closed Screen
This contains the following options:
•
ESC interface baud rate
. This can be set in the range 110 baud to 115,200 baud.
•
ESC interface character length.
This can be set to 7 or 8 bits.
•
ESC interface parity polarity.
This can be set to
None
,
Even
or
Odd
.
•
Enable backward alarm
. This controls whether a backward alarm facility is
supported as part of the ESC channel.
•
ESC interface type.
This specifies which of the modem’s physical interfaces is to
be connected through to the satellite ESC channel as described below.
Note that the rear-panel Async ESC connector provides either a high-rate asynchronous
ESC interface for IBS and Closed Network Plus ESC overhead channel data, or it
provides the Aux function. When an IDR interface card is fitted then the rear-panel shared
Async ESC port is disabled and the IDR card provides separate ESC and Aux ports.
In the case of RS232, RS422 and RS485, the relevant physical interface on the Async
ESC port is directly connected through to the ESC channel and the data is therefore
passed transparently, i.e. whatever is passed through is what comes out on the
equivalent interface on the remote modem, without being interpreted in any way by either
modem. For example, messages could be passed to control any manufacturer’s piece of
equipment that is listening on an RS485 multidrop bus at the remote modem.
An IP mode allows IP packets to be sent over the satellite ESC channel. The ESC
channel forms part of an Ethernet bridge and the modem therefore learns which IP
packets should be sent over the ESC channel. The IP packets need not be destined for
the remote modem as they will be passed onto the remote Ethernet network if they are
addressed to a device on that network. The IP packets will be interleaved with AUPC
messages when AUPC is switched on. RS485 M&C messages can be sent over the
satellite ESC channel at the same time as IP packets, provided that the M&C messages
are prefixed with
ESC
as described in the document ‘
Remote M&C Specification for
Q-
Flex™
Satellite Modem
’.