Continuous Scans

Continuous mode scans are measurements on-the-fly: Motors are running from start to stop while the counters are read. Here are the details:

 The scan timer must be of th the type DGG or DGG2.

 The user may select a scan clock (Continuous scan options), also DGG or DGG2.

 The default number of points is 5000. It can be increased on demand.

 The user specifies start, stop, step width and Sweep time. The sample time is calculated using the number of stops and the sweep time.

 The position is read before and after the counters are busy. The current position is set to the mean of both readings and stored in the x-column of scan_name. The difference of both readings is stored in scan_name_dp. The step position is stored in scan_name_steps. It is also the mean of two readings.

 The description of the scan cycle:

 The position is read, stored in pos1.

 Wait for scan_timer.

 The counters are read.

 If scan_clock is supplied, the elapsed time is stored in scan_name_time [microseconds].

 The counts are stored after the offset has been subtracted.

 The counters are cleared.

 The current position is replaced by (pos2+pos1)*0.5.

 The current step position (steps_pos2+steps_pos1)*0.5 is stored in scan_name_steps.

 scan_name_dp is filled (pos1 - pos2).

 scan_timer is started using sample time.

 The position is read, stored in pos2.

 Display after update-cycle

Note:

i	There are restrictions on the devices that can be used in continuous scans: no MCAs or virtual counters.
ii	There is no strict relation between position reading and counter reading. The maximum difference can be found in the SCAN scan_name_dp.
iii	There is a multi channel scaler (MCS) that garantees a strict relation between the motor positions and the counter readings. Ask for an implementation, if you need it.