Timer Trigger Powerdown Problems

The information provided is for help with Commtest Instruments products:

• MMS data loggers

SYMPTOMS

When the instrument is set to:

• Wake up every 5 seconds
• Take a sample
• Go to sleep for a few seconds

• Wake up, take more samples, go to sleep etc

We have found that some instruments will miss the scheduled wake up time; instead they wake up 24 hours later.

This only occurs:

• In Timer Trigger mode
• With the Log Period set to the minimum time ( 5 seconds)

• PowerDown after recording enabled

CAUSE

The instrument uses a real-time clock to schedule the wake up time. Because of the 3 second warm up time (minimum) and a 2 second 'house keeping tasks' time, some instruments miss the scheduled wake up if the clock's second counter rolls over. This causes the next wake up time to occur in 24 hours. This only happens for PowerDown periods of fewer than 7 seconds.

SOLUTION

Do not enable PowerDown for Log Periods shorter than 10 seconds.

There are two methods that allow you to gather data every 5 seconds:

• Set the Trigger to Manual Trigger.
• Set the Sample Period to 5 seconds.

OR

• Set the trigger to Timer Trigger.
• Set the Sample Period to 1 second.

• Set After Recording: Remain Awake.

No functionality is lost with these alternatives, which both avoid powering down for short times (i.e. offer no energy savings). In future releases the minimum PowerDown time will be set to 10 seconds.

FAQ ID: 11663 Last Reviewed: 27/09/2005