Merge branch 'L2SS-974_ccd_alarm_fixes' into 'master'

L2SS-974 ccd alarm fixes

Closes L2SS-974

See merge request !430

tangostationcontrol/tangostationcontrol/devices/ccd.py

@@ -118,7 +118,7 @@ class CCD(opcua_device):
     def reset_hardware(self):
         """ Initialise the CCD hardware. """
 
-        # Cycle clock
+        # Cycle clock. Quickly toggling the heater should not cool the heater down too much.
         self.CCD_off()
         self.wait_attribute("CCDTR_translator_busy_R", False, self.CCD_On_Off_timeout)
         self.CCD_on()
@@ -126,16 +126,20 @@ class CCD(opcua_device):
 
         if not self.read_attribute("CCD_PLL_locked_R"):
             if self.read_attribute("CCDTR_I2C_error_R"):
-                raise Exception("I2C is not working. Maybe power cycle subrack to restart CLK board and translator?")
+                raise Exception("I2C is not working.")
             else:
-                raise Exception("CCD clock is not locked")
+                logger.warning("CCD not locked, this may indicate the clock has not yet warmed up")
 
     def _disable_hardware(self):
-        """ Disable the CCD hardware. """
+        """ Disable the CCD hardware.
+        WARNING: The CCD contains a heater that takes about 15 minutes to fully heat up from a cold start.
+        This
+        """
 
         # Turn off the CCD
         self.CCD_off()
         self.wait_attribute("CCDTR_translator_busy_R", False, self.CCD_On_Off_timeout)
+        logger.debug("Put CCD in off state")
 
     # --------
     # Commands