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KB000352: M210/M211 Real Time Clock

The RTC can provide a one off time to the M210, only if the clock has no time since power on. Setting Valid Time Off means that when the RTC loads the clock it is marked as 'Manual Time'; when Valid Time is On it is flagged as 'Valid Time', with a 4 minute timeout on the 'Loaded' flag. Changing the Valid Time menu setting after the RTC has loaded the M210 will not change the value of the M210's flag.

If the RTC Write Switch is on, the RTC time is updated with UTC once per minute from the M210 if 'Valid Time' is flagged. The RTC time can not be manually set.

The year value entered in the IRIG menu is used only at the point when a decoded IRIG time is loaded to the clock.

Time entry through the Configuration menu is not possible if the M210 'Valid Time' flag is set.

Suggested sequence to solve this problem:

  1. Turn the RTC read valid time switches off, the write switch on, and disconnect IRIG.
  2. Repower the M210 and set the IRIG Year to 07.
  3. (optionally turn off the M210)
  4. Attatch the IRIG source
  5. (turn on the M210)
  6. allow the clock to load - the year applied now should be the current year.
  7. set the wait a couple of minutes to allow the RTC time to be corrected. This is observed on the display content for the RTC slot, by seeing that the RTC time matches the M210 time.
  8. Set the RTC read and valid time switches as required

If at point f the wrong year is applied there is one of two things going on:

  • The software is of a vintage where there was some automatic IRIG/AFNOR code recognition going on. The software has found some data at a point where there may be a date and the data at the year position is '00'. This would be confirmed by seeing an audio PC recording of the IRIG signal
  • there is a software fault and the year value set in the menu is not correctly used.
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