Reset soft trigger acquisition when max frame counter is reached (#76)

* Reset soft trigger acquisition when max frame counter is reached

* Bump NUMFRAMESTOACQUIRE to maximum value

* Rename variables

Author: stefsmeets

instamatic/camera/camera_merlin.py

@@ -47,6 +47,7 @@ def MPX_CMD(type_cmd: str = 'GET', cmd: str = 'DETECTORSTATUS') -> bytes:
 class CameraMerlin:
     """Camera interface for the Quantum Detectors Merlin camera."""
     START_SIZE = 14
+    MAX_NUMFRAMESTOACQUIRE = 42_949_672_950
 
     def __init__(self, name='merlin'):
         """Initialize camera module."""
@@ -138,12 +139,12 @@ def setup_soft_trigger(self, exposure=None):
 
         self._frame_number = 0
 
-        # Set NUMFRAMESTOACQUIRE to a large number
-        # Merlin will only collect this number of frames with SOFTTRIGGER
-        self.merlin_set('NUMFRAMESTOACQUIRE', 10_000)
+        # Set NUMFRAMESTOACQUIRE to maximum
+        # Merlin collects up to this number of frames with a single SOFTTRIGGER acquisition
+        self.merlin_set('NUMFRAMESTOACQUIRE', self.MAX_NUMFRAMESTOACQUIRE)
 
-        self.merlin_set('TRIGGERSTART', '5')
-        self.merlin_set('NUMFRAMESPERTRIGGER', '1')
+        self.merlin_set('TRIGGERSTART', 5)
+        self.merlin_set('NUMFRAMESPERTRIGGER', 1)
         self.merlin_cmd('STARTACQUISITION')
 
         start = self.receive_data(nbytes=self.START_SIZE)
@@ -175,7 +176,10 @@ def getImage(self, exposure=None, binsize=None, **kwargs) -> np.ndarray:
             self.setup_soft_trigger(exposure=exposure)
         elif exposure != self._soft_trigger_exposure:
             logger.info('Change exposure to %s s', exposure)
-            self.teardown_soft_trigger()
+            self.setup_soft_trigger(exposure=exposure)
+        elif self._frame_number == self.MAX_NUMFRAMESTOACQUIRE:
+            logger.debug(('Maximum frame number reached for this acquisition, '
+                          'resetting soft trigger.') % self.MAX_NUMFRAMESTOACQUIRE)
             self.setup_soft_trigger(exposure=exposure)
 
         self.merlin_cmd('SOFTTRIGGER')