Introduction

The NTP page displays information about the network time service. There are three versions of this page, depending on the CPU firmware version and NTP mode:

  • Versions earlier than V4.01 display SNTP content.

  • Version V4.01 and later display NTPv4 content, either:

    • Client / Server mode

    • Server only mode

Configure this service in Control Expert.

Open the Page

Access the NTP page from the Diagnostics tab (Services > NTP ):

SNTP content
NOTE:

  • Click Reset Counters to reset all dynamic counters to 0.

  • This page is updated every 5 seconds.

NTP content – Client/Server mode
NTP content – Server only mode

Diagnostic Information

The Network Time Service synchronizes computer clocks over the Internet for the purposes of event recording (sequence events), event synchronization (trigger simultaneous events), or alarm and I/O synchronization (time stamp alarms):

SNTP and NTPv4 Common Data:

Field

Description

Service Status

Running

The NTP service is correctly configured and running.

Disabled

The NTP service is disabled.

Unknown

The NTP service status is unknown.

Current Date (SNTP),
Date (NTPv4)

SNTP: the current date in the selected time zone.

NTPv4:

  • System: the local CPU date.

  • UTC: the same date in UTC.

Current Time (SNTP),
Time (NTPv4)

SNTP: the current time in the selected time zone.

NTPv4:

  • System: the local CPU time.

  • UTC: the same time in UTC.

Time Zone

The time zone in terms of plus or minus Universal Time, Coordinated (UTC).

DST Status

Running

DST (daylight saving time) is configured and running.

Disabled

DST is disabled.

Unknown

The DST status is unknown.
SNTP Data Only:

Field

Description

Server Status

green

The server is connected and running.

red

A bad server connection is detected.

gray

The server status is unknown.

Server Type

Primary

A primary server polls a master time server for the current time.

Secondary

A secondary server requests the current time only from a primary server.

NTP Service Statistics

These fields show the current values for service statistics.

Number of Requests

This field shows the total number of requests sent to the NTP server.

Success Rate

This field shows the percentage of successful requests out of the total number of requests.

Number of Responses

This field shows the total number of responses received from the NTP server.

Last Error

This field contains the error code of the last error that was detected during the transmission of an e-mail message to the network.

Number of Errors

This field contains the total number of e-mail messages that could not be sent to the network or that have been sent but not acknowledged by the server.
NTPv4 Data Only:

Field

Description

Service Type

Always NTP v4

Mode

The CPU’s NTP role or roles:

  • Server only: The CPU provides time data to local NTP client devices.

  • Client / Server: The CPU receives time data from a remote NTP server, and also provides time data to local NTP client devices.

Sync

The CPU time is synchronized:

  • In Client / Server mode: to an external NTP server.

  • In Server only mode: in the CPU configuration.

Service Statistics

In Client / Server mode:

Root delay

As NTP client, the round trip request delay, in milliseconds, from a client to a stratum 1 server.

Root dispersion

A NTP client, the additional delay contributed by other factors.

Accuracy

As NTP client, the estimated difference between local (client) time and server time.

Server Status

Ref. ID

IPv4 address of the time source.

Stratum

The relative position in the hierarchy between this client and the original time source (stratum 1) reference. If the mode is:

  • Server/Client: the value equals the system peer stratum value + 1.

  • Server only (or orphan): a user-defined value.

Polling Time

As NTP client only: the polling interval, in seconds.

<NTP Peers Statuses>
(NTP clients only)

NTP client CPU can be configured with up to 8 time source peers, each a potential server to the CPU NTP client.

IP

Peer IPv4 address of the peer.

Ref. ID

IP address of the time source used by the peer.

Select

Indicates the peer used as the time source (Current) and other viable peer time sources (Candidate).

Reach count

Percentage of NTP messages successfully sent to and received from the peer.

Stratum

The relative position in the hierarchy between this client and the original time source (stratum 1) reference.

Poll

Polling interval, in seconds.

Delay

Time to send request / receive response.

Offset

The value to subtracted from received time value to obtain time value to be applied.

Jitter

Variability in delay.