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Drivers Manual

NTP Client (Network) - 18

Description

Driver for PPS (Pulse-Per-Second) support where the UTC time is determined by interrogating an NTP or SNTP Time server.

NTP stands for Network Time Protocol (S= Simple) and is the standard for computer clock synchronization on the internet.

Optionally this driver can be used in combination with a QPS PPS Adapter for increased accuracy. The driver acts as a stand alone SNTP (Simple Network Time Protocol) client that interrogates a single NTP server on the network.

Clock synchronization accuracy will depend on network load and of course the accuracy of the time server. Benchmark tests in combination with the Qinsy SNTP Server application showed that the overall clock accuracy is about 1 millisecond.

Due to historic reasons the driver will interrogate the server once per second. This rate is far too high for usage with public NTP servers! For testing you can use a public NTP server but be warned that if you use public NTP servers for a prolonged period they will kick you off the server and put your IP number on the black list.

PPS and Timing preferred

Although benchmarks showed that the accuracy is good enough for time-stamping any serial data time, it would be preferable that timing critical sensors (motion, multibeams, lasers) are PPS (Time) synchronized themselves.

Driver Information

Driver NTP Client (Network)  Interface Type UDP  Driver Class Type
UTC Driver (question) Yes Input / Output Input  Executable DrvPpsNtp.exe 
Related Systems

Related Pages



Interfacing Notes

 An example of public NTP servers (plenty more on the internet, IP numbers may be subject to change):

91.148.192.49

0.nl.pool.ntp.org

129.6.15.29

time-b.nist.gov

192.238.48.3

1.uk.pool.ntp.org

Note that the firewall of your company network may not allow EXTERNAL NTP traffic (port 123). Consult your network administrator.

In order to achieve millisecond accuracy the server should be on the local network and preferably be directly synchronized to PPS (Stratum 1). An example of such a server can be QINSy's own SNTP Server, a GPS receiver with built-in NTP server (various Trimble models) or a dedicated Hardware NTP Server (www.meinberg.de).

System Configuration

Important

Always verify in the Time Synchronization Display that the clock is stable. Note that immediately after start-up of Qinsy the stability of the clock is building until it reaches its maximum stability after 90 seconds.

Database Setup

Add a new PPS (Time Synchronization) System to the setup. Select Driver "NTP Client (Network)". Port number is by default 123, but when used in combination with the Qinsy SNTP server you can use a user-defined port number. Note that a GPS NTP server will always use port 123.
IP number should be the IP of the server computer or hardware device.  Maximum update rate is not used.

How-to SNTP Server

Please check our Knowledge Base and read the 'How-to SNTP Server'.