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Goal

In order to maintain accurate time in GRIDlink the network must provide a path to a Network Time Protocol (NTP) Server. This requires out going port UDP 123 to be open. This is a very common practice even on the most secure networks.

GRIDlink continuously updates its internal clock from the time server and can go for weeks or months without syncing and still maintains accurate time within a few seconds.

Logs of this update can be found on the Status report. Example:
18 Feb 15:13:58 ntpdate[19573]: adjust time server 45.33.0.93 offset 0.057035 sec

On rare occasions if a GRIDlink is rebooted and communication to the NTP Server is not available, it has been observed that the on-board clock can default to a time some months or years in the past.

This does not affect the ability of the GRIDlink to respond accurately to an Open ADR Event because the current time is given to the GRIDlink from the DRMS Top Node in the payload notification.

It may however prevent the GRIDlink from connecting to GRIDview. The GRIDview server treats a Client with incorrect time as a possible security risk.

During this period logged data in the GRIDview database may have an incorrect time stamp.

Solution

The internal clock is constantly monitored, converted into epoch and validated.

Time is validated against the last valid time recorded in non-volatile memory, the time provided by the DRMS Top Node and a hard coded time stamp in the control program.

When the internal clock epoch value departs significantly from the comparative values the Clock  Alarm becomes TRUE.

The Clock  Alarm will not reboot unless the up-time since the last reboot is greater than 3600 seconds or 1 hour. This gives the system the ability to correct itself normally and prevent instability. The process repeats every hour until the time is valid.

GRIDlink will not reboot due to a Clock Alarm if there is a Pending or Active Event in progress.

The System Information Module must be active in order for this to work.

Logic Diagram

Logic

(aa)  Permissives

Conditions which will not allow an automatic reboot:

 

  1. Run time since last reboot is less that 1 hour.
  2. Pending, Moderate or High Open ADR Signal received.
  3. Pending, Moderate or High DRES Signal received.
  4. Relay 2 and/or 3 are On manually

Test Module – GRIDview

 

A special testing template is provided to simulate an internal clock error. The user can introduce erroneous values directly into the registers which monitor the time of the internal clock. There is a 50 second window between the 1 minute updates.

Follow these steps:

  1. Check that the System Information Module is detected.
  2. Make changes to the Internal Clock and see results.
  3. Make changes to the reference clock and see results.
  4. To confirm a reboot, the record is time stamped.

The Clock Error Alarm will trigger a reboot but is limited to once per hour. Also it will not reboot during an Event or if any of (aa) Permissives are True.

TEST PROCEDURE

ClockAlarm Test Procedure r0

Test Module – Toolkit

 

Uptime

To perform the Clock Alarm test using you must first connect to the GRIDlink locally.

Connect using Ethernet more …

Connect using Serial more …

Open Test I/O to access the appropriate registers to introduce erroneous values directly in Tab L IN. There is a 50 second window to make this entry in between time updates.

Then follow these steps:

  1. Check that the System Information Module is operational by observing LI958 (Uptime) is incrementing.
  2. Make changes to the Internal Clock LI15 (epochTIME). An incorrect number will trigger a reboot.
  3. Make changes to the Reference Clock  LI19 (epochTIMEref). An incorrect number will trigger a reboot.
  4. To confirm a reboot, a loss of connection will occure. When the connection is restored LI958 (Uptime) should be lower than it was.

The Clock Error Alarm will trigger a reboot but is limited to once per hour. Also it will not reboot during an Event or if any of (aa) Permissives are True.