added waitForField() to ips120.py

labdrivers/oxford/ips120.py

@@ -14,6 +14,7 @@
     ips120: a class for interfacing with a IPS 120-10 magnet power supply
 
 """
+import datetime as dt
 import time
 import logging
 
@@ -46,7 +47,7 @@ def __init__(self, GPIBaddr):
         """Connect to an IPS 120-10 at the specified GPIB address
 
         Args:
-            - GPIBaddr(int): GPIB address of the IPS 120-10
+            GPIBaddr(int): GPIB address of the IPS 120-10
         """
         self._visa_resource = resource_manager.open_resource("GPIB::%d" % GPIBaddr)
         self.setDisplay('tesla')
@@ -61,7 +62,7 @@ def setControl(self, state=3):
         3 - Remote & Locked
 
         Args:
-            - state(int): the state in which to place the IPS 120-10
+            state(int): the state in which to place the IPS 120-10
         """
         assert type(state) == int, 'argument must be integer'
         assert state in [0,1,2,3], 'argument must be one of [0,1,2,3]'
@@ -73,39 +74,39 @@ def readField(self):
         """Read the current magnetic field in Tesla
 
         Returns:
-            - field(float): current magnetic field in Tesla
+            field(float): current magnetic field in Tesla
         """
         return self._visa_resource.query_ascii_values('R 7')
 
 
-    def readSetpoint(self):
+    def readFieldSetpoint(self):
         """Read the current set point for the magnetic field in Tesla
 
         Returns:
-            - field(float): current set point for the magnetic field in Tesla
+            setpoint(float): current set point for the magnetic field in Tesla
         """
         return self._visa_resource.query_ascii_values('R 8')
 
 
-    def readSweepRate(self):
+    def readFieldSweepRate(self):
         """Read the current magnetic field sweep rate in Tesla/min
 
         Returns:
-            - field(float): current magnetic field sweep rate in Tesla/min
+            sweep_rate(float): current magnetic field sweep rate in Tesla/min
         """
         return self._visa_resource.query_ascii_values('R 9')
 
 
     def setActivity(self, state=1):
         """Set the field activation method
 
-        0 - Hold
-        1 - To Set Point
-        2 - To Zero
+        0 - Hold  
+        1 - To Set Point  
+        2 - To Zero  
         3 - Clamp (clamp the power supply output)
 
         Args:
-            - state(int): the field activation method
+            state(int): the field activation method
         """
         assert type(state) == int, 'argument must be integer'
         assert state in [0,1,2,3], 'argument must be one of [0,1,2,3]'
@@ -120,7 +121,7 @@ def setHeater(self, state=1):
         2 - Heater On, no checks    (open switch)
 
         Args:
-            - state(int): the switch heater activation state
+            state(int): the switch heater activation state
         """
         assert type(state) == int, 'argument must be integer'
         assert state in [0,1,2], 'argument must be one of [0,1,2]'
@@ -133,7 +134,7 @@ def setFieldSetpoint(self, field):
         """Set the magnetic field set point, in Tesla
 
         Args:
-            - field(float): the magnetic field set point, in Tesla
+            field(float): the magnetic field set point, in Tesla
         """
         MAX_FIELD = 8
         assert abs(field) < MAX_FIELD, 'field must be less than {}'.format(MAX_FIELD)
@@ -145,7 +146,7 @@ def setFieldSweepRate(self, rate):
         """Set the magnetic field sweep rate, in Tesla/min
 
         Args:
-            - rate(float): the magnetic field sweep rate, in Tesla/min
+            rate(float): the magnetic field sweep rate, in Tesla/min
         """
         self._visa_resource.write("T{}".format(i))
 
@@ -154,7 +155,7 @@ def setDisplay(self, display):
         """Set the display to show amps or tesla
 
         Args:
-            - display(str): One of ['amps','tesla']
+            display(str): One of ['amps','tesla']
         """
         assert display in ['amps','tesla'], "argument must be one of ['amps','tesla']"
 
@@ -163,3 +164,29 @@ def setDisplay(self, display):
                     }
 
         self._visa_resource.write("M{}".format(mode_dict[display]))
+
+
+    def waitForField(self, timeout=600, error_margin=0.01):
+        """Wait for the field to reach the set point
+
+        Args:
+            timeout(int): maximum time to wait, in seconds
+            error_margin(float): how close the field needs to be to the set point, in tesla
+
+        Returns:
+            (bool): whether the field set point was reached
+        """
+
+        start_time = dt.now()
+        stop_time = start_time + dt.timedelta(seconds=timeout)
+
+        while dt.now() < stop_time:
+            field = self.readField()
+            set_point = self.readFieldSetpoint()
+
+            if abs(field - set_point) < error_margin:
+                return True
+
+            time.sleep(5)
+
+        return False