Appears to be the same failure mode as yesterday.
We have left the Beckhoff chassis in the blown-fuse state. We have successfully restarted the frontend models (see below), but the Beckhoff will not run properly without this chassis, so we cannot continue tonight.
To bring the frontend models back: Nic shut off the PSL frontend and Sheila power cycled the IO chassis. Then Nic started the PSL frontend. This didn't work the first time, so Nic shut down the PSL frontend again, unplugged and plugged in the power cable, then turned it back on.
according to Daniel, we could have recovered partially from this last night by going into the system manager, right clicking on the bad chassis and selecting disable. Then a red X would appear over that chassis. If we redo the generate mappings, check configuration, activate confguration, the system should run again.
Attached is a screenshot of the TwinCAT System Manager. The context menu will bring up the option to disable an entire EK1100 chain. Once disabled, a red X should be visible in the overview. After disabling the offending chassis or module, one has to generate the mapping, check the configuration and activate the configuration (see second screenshot). Make sure you are in run-time mode.
Caveat: The chassis are daisy chained. Turning off a chassis will no only disable the chassis itself, but all units which are hanging off this chassis. Using an Ethernet coupler it is possible to bypass a single chassis.