added attenuator

devices/attenuator.py

@@ -0,0 +1,74 @@
+from time import sleep
+from types import SimpleNamespace
+
+from slic.utils import typename
+from slic.core.task import Task
+
+
+import epics
+
+class PV(epics.PV):
+
+    def put(self, *args, wait=True, **kwargs):
+        super().put(*args, wait=wait, **kwargs)
+
+
+
+class Attenuator:
+
+    def __init__(self, name, n_motors=6):
+        if not name.endswith(":"):
+            name += ":"
+        self.name = name
+        self.pvs = SimpleNamespace(
+            energy = PV(name + "ENERGY"),
+            transmission = PV(name + "TRANS_SP"),
+            motors_done_moving = [PV(name + "MOTOR_{}.DMOV".format(i+1)) for i in range(n_motors)]
+        )
+
+
+    def get_current_value(self):
+        return self.get_transmission()
+
+    def set_target_value(self, value):
+        def changer():
+            self.set_transmission(value)
+        return Task(changer)
+
+
+    def set_transmission(self, value):
+        self.pvs.transmission.put(value)
+        self.wait_for_motors()
+
+    def get_transmission(self):
+        return self.pvs.transmission.get()
+
+    transmission = property(get_transmission, set_transmission)
+
+
+    def set_energy(self, value):
+        self.pvs.energy.put(value)
+
+    def get_energy(self):
+        return self.pvs.energy.get()
+
+    energy = property(get_energy, set_energy)
+
+
+    def motors_are_moving(self):
+        is_moving = lambda dmov: not bool(dmov.get())
+        return any(is_moving(dmov) for dmov in self.pvs.motors_done_moving)
+
+    def wait_for_motors(self):
+        while self.motors_are_moving():
+            sleep(0.01)
+
+
+    def __repr__(self):
+        tn = typename(self)
+        trans = self.get_transmission() * 100
+        energ = self.get_energy()
+        return "{}(\"{}\") at {}% transmission for {} eV".format(tn, self.name, trans, energ)
+
+
+