The Seconds Between Poll field refers to how often all devices will be polled. If you enter "0", then polling will be disabled.
The Show Progress While Polling field, when checked, causes a status box to display while devices are being polled. Typically it takes less than a second to poll all devices, however, so you should typically disable this feature.
Polling is performed by querying devices starting at logical controller #0, starting with the lowest SCSI ID per controller. All SCSI devices are polled in ascending order. When all devices on a controller are polled, the next controller is polled, and the process continues. IDE drives are polled in the order primary master, primary slave, secondary master and secondary slave.
S.M.A.R.T. Disk Monitor does not attempt to discover new devices. We do, however have plans to enable discovery in the future.
The section entitled, Principles of Operation details the sequence SMART Disk Monitor performs when polling devices.