[Gb-ccb] suggested changes to ccb library

[John Ford]

Martin Shepherd writes:
 > 
 > On Mon, 11 Aug 2003, Brian Mason wrote:
 > >...
 > > The issue is that a new scan can't start until the current integration
 > > is done. Potentially this is a longer delay than we want.
 > 
 > This can be fixed at the hardware/driver level, so there is no need
 > for a software workaround.
 > 
 > Having said this, I am wondering what you consider to be too long of a
 > delay for a new scan to start, especially given that we were planning
 > on very short, 1ms integrations? Observing scans are supposed to start
 > on one-second boundaries, so the manager needs to inform the server
 > sufficiently far in advance of the target second that the driver
 > receives the request before that second has passed. Since the request
 > is going over the ethernet, and neither the manager, nor the server
 > are to be real-time processes, getting this reliably right will
 > probably require the manager to send the message at least a second in
 > advance.

The 1 ms integrations will be summed into longer integrations,
presumably, and these longer integrations are assumed to be the units
upon which the scans are stopped and restarted.  It should be possible
for the control manager to send either a "stop" command, which will
stop the device in a sane manner, i.e. after a full cycle of phases,
and an "abort" command, which will stop the data taking immediately.

On our other backends, integrations are typically many seconds or
even minutes long.  This may not be the case here, but, ???

John