CERN Accelerating science

Power converter timing events

Following recent updates to the FGC and power converter gateway
software, the following three timing events are now supported and are
operational:

1. Global post-mortem - this event will trigger an external post-mortem
for all converters.  The post-mortem will consist of 1 minute 50Hz
status buffers from the gateways, centred around the time of the trigger.

2. Start FGC reference - this event will trigger FGCs that are in the
ARMED state to start running their reference functions.  There is a
200ms delay between the time of the event and the starting of the function.

3. Abort FGC reference - this event will trigger FGCs that are in the
RUNNING state to abort their references smoothly over a period defined
by the property REF.ABORT_PERIOD (10 seconds by default).  FGCs in the
ARMED state will immediately switch to the IDLE state on application of
the event.  There is a 200ms delay between the time of the event and the
start of the abort.

The low byte of the payload for a start or abort event is used to
determine which FGCs will react to the event.  The byte is known as the
"event group" and will allow several different applications to work with
different groups of power converters at the same time without
unintentionally triggering references on other FGCs to start or abort.
It is expected that there will be a piece of software acting as a
"ticket machine" issuing event groups to applications.

There are two special values for an event group:

0: An event group with a value of zero will cause all FGCs in a relevant
state to react to the event.

255: Event group 255 is reserved for PO internal use.

By default, an FGC is only sensitive to event group 0.  An FGC may be put into an event group in addition to group 0 by setting the REF.EVENT_GROUP property to the event group number.

When an FGC ceases to be in either of the ARMED or RUNNING states REF.EVENT_GROUP is cleared.