I think you could do both of Mark's suggestion at the same time yielding periodically scanned status records that also get scanned immediately when an associated "set" record is written to.
Yep.
Manual on-demand scanning could be implemented with an OPI button that writes to the record's PROC field.
Sometimes I have seen different scan rates being applied based (using a seq record) on device status: poll fast when things are "moving", poll slow when things are not.
BTW. This issue is not particular to StreamDevice at all.
Any readback from a device that has to be actively polled will act the same way.
Cheers,
~Ralph
