michael.cook at sfr.fr
Thu Aug 11 12:07:09 EDT 2016
> Le 11 août 2016 à 12:15, Martyn Smith <martyn at ptsyst.com> a écrit :
> I have a strange fault on a PRS10. Wondered if anyone had seen it.
> I am running a PRS10 and at the same time monitoring its FC (the frequency control value) and Status byte data values.
> So normally, the Status shows are all zeros, except 2nd from last is a 1, showing the unit is not receiving any 1 pps signals.
> What happens is the FC value suddenly jumps from its current setting (-150 for example) to zero, for no apparent reason.
if -150 is really what you saw, then it is out of bounds as the two values returned by fc? are both +ve.
if they go to zero, check the eeprom values
58,5485,1534,1434 for example
If they are reasonable then possible the eeprom is not being read correctly after reset.
> Then a short while later, the Rubidium's status bytles go crazy, mostly to FF.
This indicates a microprocessor reset . After a power cycle you can see:
255,255,255,243,162,255 ie most FF
when you read again you get the current values
0,0,0,0,130,0 for example
then if you reset the microprocessor
255,255,255,243,162,255 back to the initial state
So it looks like you are getting resets. Possibly from brown outs. Maybe a low power condition at reset prevents eprom data being read correctly.
Are the affected RBs on the same power supplies?
> Then the rubidium goes back to the previous correct state (all zeros) but the FC value is now zero.
> If you do connect a 1 pps, you get the same fault.
> The confusing thing is I've suddenly seen this on 3 or 4 different rubidium's. Some brand new, some five years old.
> Obviously suspect the power supply, but it doesn't seem to be that.
> Best Regards
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