WESTERSTRAND
Document: DOK11018en02
Author: PM/CF
Analogue NTP Clock
Date: 2020-09-24
Page: 2 of 21
WESTERSTRAND URFABRIK AB
P.O. Box 133
Tel. +46 506 48000
Internet:: http://www.westerstrand.se
SE-545 23 TÖREBODA
Fax. +46 506 48051
E-mail:
General
Westerstrand Analogue NTP Clock with Power over Ethernet (PoE) connection provides the possibility to create a
time distribution system with high accuracy and high reliability.
The NTP Clock is equipped with two motors, 3 hands analogue movement. Initial setting function and error
correction is automatic. The movement starts automatically after reception of correct time.
The hour hand is sweeping, minute and second hands are stepping.
LAN connection
The NTP clock is equipped with a RJ45 (10/100BASE-T) connector for direct connection to the LAN via a Power-
Over-Ethernet switch.
Each clock has a unique IP address. The IP address, gateway, subnetmask etc can be set manually (static IP) using
a web browser (or telnet) or it can be set automatically using DHCP (dynamic IP).
The clock normal delivery mode is DHCP (dynamic IP with fallback address 192.168.3.10). Otherwise the IP
address is labelled on the clock.
Power-Over-Ethernet
Power-over-Ethernet (PoE) is a network standard based on IEEE 802.3af that provides a means of delivering power
to devices connected to the LAN. This technology eliminates AC electrical wiring, wall transformers, allows
centralised UPS backup, and is fully compatible with both powered and non-powered Ethernet devices.
In addition to providing time synchronisation and control over Ethernet, PoE enabled Ethernet cable provides
power to the clock. System installers need run only a single Ethernet cable that carries both power and data to each
clock. This allows greater flexibility placing clocks and, in most cases, significantly decreases installation costs.
Westerstrand clocks are fully compliant with the IEEE 802.3af standard for providing power over Ethernet.
NTP
To distribute correct time to different users in a Local Area Network (LAN) the Network Time Protocol (NTP) can
be used. NTP is a part of the protocol family TCP/IP. The unit that sends out the time is called NTP Server and the
clock that receives the time is called NTP Client.
There are some different ways (work modes) that can be used for distribution of time according to the NTP
standard.
The NTP clock supports three different work modes:
1. Unicast client mode (point to point). A unicast client (the NTP clock) sends a request to a designated NTP server
at its unicast address and expects a reply from which it can determine the time, the roundtrip delay and local clock
offset relative to the server. The IP address of the NTP server is to be entered manually.
2. Same as work mode 1, but the IP address of the NTP server is received automatically from the DHCP server
(option 042). The clock delivery mode is this option.
3. Broadcast/Multicast mode (point to multipoint). A multicast NTP server periodically sends a unsolicited message
to a designated local broadcast address or multicast group address (224.0.1.1) and ordinarily expects no requests
from clients. A multicast client (the NTP clock) listens on this address and ordinarily sends no requests.