At the moment EigerTriggerInfo is defined here to be the standard TriggerInfo, but with energy too, so that it can be done all in one go.

This means we can't use it in standard plans.

The desired sequence for setting up detectors should be:

• Set individual settings for detector via a custom detector plan, for Eiger this should set all the parameters (including energy and MX settings), but not wait for the detector to respond (i.e. don't wait for the stale parameters light to go out)
• In EigerController.prepare then set the exposure time and number of triggers, and wait for the stale parameters light to go out
• In EigerContrller.arm then actually arm the detector

The idea is that the plans cannot be parallelized, so need to be fast, but prepare can be parallelized with things like motor moves, so it's better to put the waiting there.