Paradise Datacom P300-VSAT Installation & Operating Handbook page 165

Eurocom D/1 interface `D` operation
The Eurocom `D` interface uses transformer coupled differential clock and data signals. The data signal
is AMI coded, and the amplitude of both clock and data signals is ±0.5V (ie 1.0 V peak to peak). The
differential lines are of 130
be grounded, or left floating.
The Eurocom `D` interface will operate from <16kbps to >2048kbps, although the Eurocom specification
call for only 256, 512, and 1024kbps. In addition to the clock and data lines in and out (four lines), a fifth
line is implemented over and above the Eurocom specification which carries the modems internal clock
out when the Tx clock is set to internal.
Min
Signal Description
Req
DATA CIRCUIT TOWARDS MODEM (TX)
&
Clock In
&
Data In
Int' Tx Clock Out
DATA CIRCUIT FROM MODEM (RX)
&
Clock Out
&
Data Out
COMMON LINES
&
Ground to Activate Eurocom `D`
Do Not Connect
&
Signal Ground
&
Shield/Protective ground
* Links
All links settings are:
Centre tap grounded: 1-2 (link `up` with the PCB legend the right way up)
Centre tap floating 2-3 (link `down` with the PCB legend the right way up)
The typical configuration would normally be to ground the outputs, and leave the inputs floating ie:
Links 4, 5, and 7 in pos 1-2 (up), and links 1 and 2 in pos 2-3 (down)
This provides protection by ensuring the signal levels remain close to ground potential (as might happen
if both inputs and outputs were floating), but avoid any ground currents between distant locations (as might
happen if both inputs and outputs were grounded).
The modem will detect and display the `Data Marginal` warning if the Tx input clock and data phase is
incorrect, and will automatically flip the clock phase to correct this. If repeated `Data Marginal` alarms occur
then it is likely the Tx clock and data are not from the same clock course and are `slipping past` each other.
P300H
$
impedance, and the centre tap of the line coupling transformers may either
RS422
Name
SD
ST
RT
RD
SG
PG
P300 Modem Installation and Operating Handbook
Circuit
Number
TT 113
103
114
115
104
102 2, 7, 13, 15, 22, 25
101
25 pin Link to ground
centre tap of
A B
transformer
19 6
18 5
21 8
4 17
16 3
14
12, 20
1
LK 1 *
LK 2 *
LK 7 *
LK 4 *
LK 5 *
n/a
n/a
n/a
n/a
Page 165