scan: Approach the surface with stepper_approach() before looping

This makes the initial approach much faster if you are starting far
from the surface (e.g. after a calibcant calibration).

diff --git a/unfold_protein/scan.py b/unfold_protein/scan.py
index de1edda85d4ef87916470a4bb71bccb99cff2ebf..e511dfd48f42dc7c8a5c0b17664cec0b8efaec3f 100644 (file)
--- a/unfold_protein/scan.py
+++ b/unfold_protein/scan.py
@@ -34,6 +34,8 @@ class UnfoldScanner (object):
     def run(self):
         self._stop = False
         _signal.signal(_signal.SIGTERM, self._handle_stop_signal)
+        self.unfolder.afm.move_away_from_surface()
+        self.stepper_approach()
         for i in range(self.config['velocity']['num loops']):
             _LOG.info('on loop {} of {}'.format(
                     i, self.config['velocity']['num loops']))