User guide

ASCOM USER GUIDE
High Speed Base Band Modems
19
• Press the SCROLL DOWN button once. The LCD will indicate the line rate, e.g. 512K:
• Press the SELECT button until the desired rate appears.
• Press the PROG button to implement your settings. The PROGRAM LED will go out.
This confirms the changes have been made to set the modem to MASTER, at the
specified data rate and in the case of the two pair modem, with either one or two pairs
in operation.
4.3.1.3 Synchronisation
If unconnected the modems should now show the message:
The green POWER LED and the red FAULT LED should also be lit.
If the modems are connected then, after approximately a minute the red FAULT LED should go
out and the LCD should show:
The modems are now synchronised and transmitting data to one another.
4.3.2 Desktop modem to desktop modem with external timing
This configuration is similar to the previous configuration. The MASTER modem however can
be set to receive an external clock source (see diagram 2.2.2). For X21 there is an additional
option of synchronising to an external byte (octet) timing signal.
Note that the user interface connector on the rear of the unit is wired such that the modem is
a DCE (Data Circuit-terminating Equipment). If the modem is required to act as a DTE (Data
Terminating Equipment) then a changeover cable will be required. The details are given in
section 8.
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18 ASCOM USER GUIDE
High Speed Base Band Modems
With your modems connected as described above, the configuration procedure is as follows.
4.3.1.1 Configuring SLAVE unit
• Press MENU LEFT and MENU RIGHT buttons until the LCD shows the message:
• Immediately press the SCROLL DOWN button once or wait for three seconds. One of the
following messages will appear:
• If the message
is already displayed then your Modem is configured correctly for slave operation.
• Otherwise press the SELECT button until the LCD shows the message:
The PROGRAM LED will be lit to show that a change has been made but not yet programmed
into the memory.
• Press the PROG button to implement the SLAVE mode. The PROGRAM LED will go out
and your modem will now be configured as SLAVE.
4.3.1.2 Configuring MASTER unit
• Repeat the above section, but instead select the master mode:
• Press the SCROLL DOWN button once. If you have a two pair modem you can now select
one or two pair working by pressing the SELECT button, e.g. for 1 pair: