Endace Measurement Systems.
http://www.endace.com
EDM01.05-10r1 DAG 4.3S Card User Manual
35
Revision 6. 22 September 2005.
6.2.3 Card with Reference Time Synchronization
, continued
Using external
reference
source
To use an external clock reference source, the host PC’s clock must be
accurate to UTC to within one second. This is used to initialise the
DUCK.
Time accuracy is achieved using the host PC NTP. The time reference
source is connected to synchronization connector, the card automatically
synchronizes to a valid signal.
Connecting
time
distribution
server
The TDS 2 module connects to any DAG card with a standard RJ-45
Ethernet cable and can be placed some distance from a DAG card and
existing RJ-45 cabling infrastructure.
CAUTION: Never connect DAG and/or the TDS 2 module to active
Ethernet or telephone equipment.
Testing signal
For Linux and FreeBSD, when a synchronization source is connected the
driver outputs some messages to the console log file
/var/log/messages
.
The
dagpps
tool is used to test a signal is being received correctly and is
of correct polarity. To perform the test, run:
dagpps –d dagN
The tool measures input state many times over several seconds, displaying
polarity and length of input pulse.
Some DAG cards have LED indicators for synchronization (PPS) signals.
6.3 Synchronization Connector Pin-outs
Description
DAG cards have an 8-pin RJ45 connector with two bi-directional RS422
differential circuits, A and B. The PPS signal is carried on circuit A, and
the serial packet is connected to the B circuit.
Pin assignments
The DAG 4.3S card 8-pin RJ45 connector pin assignments are:
1. Out
A+
2. Out
A-
3. In
A+
4. In
B+
5. In
B-
6. In
A-
7. Out
B+
8. Out
B-
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