'''[wiki:GraspSwControllerCmd ifconfig]'''

[[TracNav(GraspContents)]]

||Command:||'''ntp'''||
||Contexts:||Network socket, serial console.||
||Function:||Displays or sets the STARGRASP controller's experimental NTP client.||
||Required Parameters:||none.||
||Optional Parameters:||'''serverip''' | "'''stop'''"(SVN rev 5715)||

=== Usage ===

'''Note: the NTP client is currently experimental. Its performance has been tested against various local NTP servers and should work reasonably well, but some of the NTP behaviour observed means that it may not react correctly in all situations and thus isn't guaranteed. See [wiki:GraspExtrasSoftwareControllerNTP NTP client performance] for details.

The STARGRASP controller includes an experimental NTP client that attempts to sync the controller to an NTP server to provide real-world times for various events.  The ''ntp'' command is used to either display the current NTP status or configure a new server.

When invoked with no options, the ''ntp'' command displays information about the current NTP configuration and status (if previously configured to use an NTP server).

When executed with a single IP address, the NTP client is reset and configured to use that IP address as the server it should synchronize itself to. Note that an IP address is required; the STARGRASP controller does not perform any name server lookups and will reject anything that isn't an IP address.

For example, to sync the controller to the public server 0.pool.ntp.org:

{{{
ntp 66.79.167.34
}}}

Note that if NTP is used it is highly recommended that the controller should be synced to an NTP server on the local network rather than a server on the public internet.

As of SVN revision 5715, the NTP client accepts "stop" in place of an IP address to stop the client. Any existing connection to an NTP server is closed and the NTP client is unconfigured and will no longer sync against a previously-configured NTP server. Note that at this point, the controller's notion of real-world time goes open-loop. The controller retains its knowledge of the last NTP sync performed (if any) but since no more updates are performed, its time will start to drift from the server's.