Meinberg TCR LANTIME - Manual (Page 22)

Booting the Single Board Computer
The LINUX operating system is loaded from a packed file on the flash disk of the
single board computer to a RAM disk. All files of the flash disk are stored in the
RAM disk after booting. Because of that it is guaranteed that the file system is in a
defined condition after restart. This boot process takes approx. one minute. After the
LINUX system has started up already the network function is initiated and the driver
software LANTIME is started. This driver tries to get a valid time from the TCR
reference clock in order to set the LANTIMEs clock. If TCR clock is not connected
the LANTIME is waiting for a valid time.
waiting for refclock on COM1
with 9600 Baud 7E2
After starting up the LINUX system the network function is initiated and the program
for communication with the TCR510 and the NTPD (NTP daemon) is started. After
that NTPD starts synchronisation with the reference clocks (usual the hardware clock
of the single board computer and the TCR). Until synchronisation is finished the
following message is displayed:
TCR: NORMAL OPERATION Wed, 18.11.2002
NTP: Not Sync MEZ 10:04:10
For the synchronisation of the NTPD with the TCR it is necessary that the IRIG-
receiver is locked with the input signal (FAIL LED is turned off and the LOCK LED
is turned on). In this case the following message is monitored on the display:
TCR: NORMAL OPERATION Wed, 18.11.2002
NTP: Offset TCR: 1ms MEZ 10:04:10
The second line shows the user that the NTPD is synchronized with the TCR with an
offset of -1 ms. Because of the internal time of the NTP which is adjusted by a
software PLL (phase locked loop) it takes a certain time to optimise this offset. The
NTPD tries to keep the offset below ±128 ms; if the offset becomes too large the
system time is set with the IRIG-time. Typically values for the offset are +-5 ms after
the NTPD has already synchronized.
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