csmstr - Omega Engineering

USING TIME MANAGEMENT
selected, the unit’s Ethernet port must be configured to use DHCP, and the
network’s DHCP server must be configured to designate a server via option 42.
• The Enable GPS property is used to instruct the time client to use a GPS unit
connected via NMEA-0183 as an alternative method of obtaining the current
time. The unit may be connected to any serial port using the appropriate driver.
• The Frequency property is used to specify how often the Master should attempt
to synchronize its time by the methods enabled above. The Master will always
attempt to sync twenty seconds after power-up, and will then sync as specified
by this property. If a given attempt to sync fails, the unit will retry every 30
seconds until it is successful. If both GPS and SNTP synchronization are
enabled, the SNTP will only be used if a GPS is not available.
LOG FILE
• The Time-Stamp Using UTC property is used to instruct Crimson to base its
event and data logging on UTC rather than on local time. This produces log files
which are more easily portable across time-zones, and which do not suffer from
discontinuities when switching in and out of Daylight Savings Time. The setting
is global, and will effect all log files within the system.
SELECTING AN SNTP SERVER
When configuring the SNTP client, you have several options when selecting a server.
If you have a Windows- or Unix-based time server as part of your network infrastructure, you
should ultimately synchronize to this source to ensure enterprise-wide synchronization. If you
have several Masters on the same network, though, you will find it better to nominate one of
these as the master device for the purpose of setting Daylight Savings Time, and then have
that Master alone synchronize to the enterprise time source. You can then configure the other
devices to synchronize to the master device, and enable the Linked DST facility to propagate
the Daylight Savings Time setting around your factory.
If you have no enterprise time source available, you may choose to nominate a single Master
as the point where an operator will set the time, and then have other Masters synchronize to
that source. Alternatively, if your installation provides TCP/IP access to the Internet via either
Ethernet or a modem connection, you may configure the SNTP client to synchronize to a
public time server. An example of this would be 192.6.15.28, which is the current IP address
of a public time server provided by NIST. A list of other servers can be found at…
http://support.microsoft.com/kb/262680
Note that since Crimson uses an IP address and not a host name to reference the SNTP server,
it will lose connection with any server that is relocated to a new network address. While such
relocations are very rare, they are beyond your control and that of Red Lion. The use of an
enterprise time source which accesses its own source via DNS is thus considered preferable!
REVISION 6 PAGE 97