DETAILED OPERATING INSTRUCTIONS |
33
PDM
PDM Operator's Manual Version 2.4a • September 2019
NTP
Enables or disables PDM’s ability to update its time-of-day clock automatically from a
Network Time Protocol server
15
(see "About NTP" below). If enabled, PDM’s clock cannot be
manually set.
NTP Server
Enter the IP address of the network time server. This menu item appears only
if NTP is enabled.
Network troubleshooting
PDM’s Internet services (such as PD-Alert e-mails, Network Time Protocol, and Web remote
control) require proper Internet Protocol addressing. In many installations this is provided
automatically by your station’s data router, when you choose DHCP (
page 32
). However,
some data networks don’t support DHCP, or require fixed IP addresses. If that is the case,
you will have to manually enter the IP Address, Subnet Mask, Gateway, and DNS numbers.
About NTP
Network Time Protocol servers supply accu rate time-of-day and other data over the
Internet. PDM can use them to automatically set its internal clock. Your facility might also
have its own NTP server.
NTP servers are often identified by a domain name—a familiar-sounding “.com” or “.gov”
URL— rather than their numeric IP address. PDM requires numeric IP addresses.
You’ll find a list of US servers, with both their domain names and their IP addresses, at
the National Institute of Standards and Technology’s website
16
. International time server
domain names are listed at www.ntp.org. Please respect the access policies listed by the
server provider and IT department. PDM users should never select a Primary server for
NTP updating; use Pool or Secon dary servers instead.
The best way we have found to test whether NTP services are working is to manually
offset your PDM clock by a couple of minutes, then enable NTP. If your network con-
nections are working and your NTP address is valid, the system clock should quickly
acquire the correct time.
If your
Information
screen shows an IP address of
0.0.0.0
and DHCP has been selected,
it is likely the router isn’t supplying a valid address. Power cycling PDM may be necessary
to activate DHCP. In some cases you may need to power cycle or reset the router as well.
Note that router resets can temporarily disrupt the entire data network.
PDM’s Network Time Protocol system will also report potential network issues while it is
establishing a connection with the time server. These messages appear on the information
screen, and are described on
page 38
.
15 The factory default is 7, which takes about two minutes to fully build an eight-second delay. That’s subtle
enough to be imperceptible to most listeners. There’s a discussion of Build Speed on page 11.
16 The list itself is currently at http://tf.nist.gov/tf-cgi/servers.cgi. If NIST has moved it from that location, use the
search box on their home page, www.nist.gov, to find “Internet Time Service”.
Summary of Contents for PDM
Page 78: ......
