Experimental Physics and
Industrial Control System

[email protected] (John R. Winans) · Thu, 23 Mar 1995 21:17:09 -0600

>It is interesting to hear you might want to do it. If you do, use a
>Bancomm 635/637 since that is what we all have.

I think the choice has been made for me already.  And from what I can tell,
it has IRIG-B (what I call to myself irate-B) commin' into it.  So I think
I am SOL on the year thing.

>>       The device ONLY provided the number of milliseconds into the current
>>       calander year.  Therefore I could not figure out what year it is.  A 
>>       rather nasty problem for an IOC that should otherwise be self contained.>       I figure that I could always ask a Unix box for the time and assume it is
>>       close ehough to get the year right.
>
>This is a problem which is very common and arises because the standard
>way for ditributing time is IRIG B, which is a serial BCD format which
>doesn't understand years. However, most GPS boards have an on board
>RTC, (most IOC's do too) which can give a guess at the year. I am
>trying to ensure that Bancomm uses this clock to provide the year.

*SIGH*  I had hope that someone would tell me I am nuts and that I missed 
something obvious.

>What I am going to do is run the whole network on GPS time and provide
>the 10 second time error as an interesting conversation piece. Anyone
>who really needs UTC can convert easily - GPS->UTC is easy, it is only
>the other way round that is hard.

Recently, someone told me that my frustrations in life come from the fact that 
I am a perfectionist.  I laughed and then thought about it for a minuite (one
of those 61 second jobbers at that) and then realized that perhaps I have been
a tad hard on defining the success point of my work.  Perhaps the temporary
inaccuracy in time stamps is simply something that I should not care about.  
I mean, the IOCs of the APS will only be out of sync with eachother for a few 
seconds (between the leap and the next resync rondezvous... a 15 second tunable 
default) anyway.  

*SIGH* I just don't know.  What does everyone else think?

--John

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System