I retested the chronobox trigger generation:

1) Inserting moderate sized pulse into channel 8 of V1725-0.
2) Configured threshold of V1725 so that channel triggers LVDS pulse into chronobox
3) Fan-out trigger out from chronobox to all V1725s.
4) busy signal from each V1725 fed into the chronobox
5) Start run, then push trigger from 20Hz up to 200Hz
6) System running stably!  Actual trigger rate about 60.2Hz.  The almost_full condition is set to 32 on the
V1725s and the estored on each board fluctuates below 32.

https://ds-proto-daq.triumf.ca/HS/Buffers/eStored?hscale=300&fgroup=Buffers&fpanel=eStored&scale=10m

The busy light on the V1725 never comes on, good.

The next thing we need is some way to start/stop the trigger generation on the chronobox, so that at
begin-of-run triggers do not get sent before the V1725s are finished configuration.

Other notes:

a) It turned out that the register to set the V1725 channel trigger threshold was different for RAW vs ZLE
firmware (0x1080 vs 0x1060); after fixing that the channel threshold seemed to work as expected.
b) Map for chronobox NIM cables:

channel 1-4: busy IN from V1725
channel 5,7,8: trigger OUT from chronobox
channel 6: clock OUT from chronobox