[foxboro] DCM showing yellow in the System Monitor? And a bad thin-net tee can wipe out a whole CP60's IO communication bus??!!

We had an interesting situation come up, thankfully only on a hot spare
CP60 system.  The remaining question is now that it is all back together
and fixed and working, why does our FCM10Ef show yellow in system
status?  All the 200 IO below it shows white.  Could it be because the
200 IO base has only primary power, there is no secondary power
connection since it is just a hot spare?  It also has only the A bus,
but that should be taken care of by running it as A, Disable Switching,
since there is no red box to indicate a network problem, only the yellow
text.
 
The original problem was complete failure of all IO.  We have this hot
spare CP60 running two enclosures with 100 IO and one with 200 IO.  So
it's thin-net from the CP to the DMC10E with a tee to the 6 port
ethernet hub along the way, then fiber from that hub to the FCM10Ef with
200 IO.  After a little trial and error, we traced it to an apparently
bad thin-net tee at the hub - we replaced that and all is well now.  But
needless to say it is disturbing that that can happen - I guess that's
why we have two buses.  It seems like every upgrade inserts more
gingerbread into the loop in the form of translator boxes, etc.  And
these things can fail, apparently with some interesting failure modes.
The hub was showing collisions with the bad tee in the system and they
went away after it was replaced.
 
 
 
 
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