Toggle safety shutter until open on Andor Laser Combiner

alc_shutter_toggle_until_open.py

"""
Toggle safety shutter until open on Andor Laser Combiner
"""

from ctypes import windll, c_ulong, byref
from time  import sleep, clock
import sys

class DeVaSys:
    """Microcontroller board in Combiner controlling laser safety interlocks
       and shutter"""
    handle = 0
    ioconfig = c_ulong(0x48000) # B7, C6 inputs, others outputs
    iodata   = c_ulong(0x84000) # B6, C7 high, others low
    B6 = 0x80000 # B6 input toggles interlock
    C7 =  0x4000 # C7 input toggles safety shutter
    B7 =  0x8000 # B7 output health ok
    ioblank = c_ulong(0) # all low
    ioread = c_ulong(0)  # initialize to zero
    lib = windll
  
    def __init__(self):
        """Instantiate DeVaSys board from library and bypass interlocks"""
        self.lib = windll.LoadLibrary("usbi2cio.dll")
        self.handle = self.lib.DAPI_OpenDeviceInstance("UsbI2cIo", 0)
        self.lib.DAPI_ConfigIoPorts(self.handle,
                                    self.ioconfig)
        self.lib.DAPI_WriteIoPorts(self.handle,
                                   self.iodata,
                                   self.B6)
    
    def shutter_open(self):
        """Open laser safety shutter"""
        self.lib.DAPI_WriteIoPorts(self.handle,
                                   self.iodata,
                                   self.C7)
        sleep(0.5) # Give the DeVaSys board time to read back the value from the Prontor shutter board
        self.lib.DAPI_ReadIoPorts(self.handle,
                                  byref(self.ioread))
        if self.ioread.value & self.B7 == 0:
            return 1 # success
        else:
            return 0
    
    def shutter_close(self):
        """Close laser safety shutter"""
        self.lib.DAPI_WriteIoPorts(self.handle,
                                   self.ioblank,
                                   self.C7)


if __name__ == '__main__':
    prog_start = clock() # assumed "0" timepoint of program execution
    
    print "[%.3f] Disengaging laser interlocks" \
          % (clock() - prog_start)
    dvs = DeVaSys()
    
    print "[%.3f] Toggling safety shutter till open" \
          % (clock() - prog_start)
    
    attempt = 1
    
    status = dvs.shutter_open()
    
    while status != 1:
        print "[%.3f] Failed to open shutter on attempt %d.  Trying again..." \
              % (clock() - prog_start, attempt)
        sleep(2) # wait 2 seconds
        dvs.shutter_close()
        sleep(2) # wait 2 seconds
        attempt = attempt + 1
        status = dvs.shutter_open()
    
    del dvs
    
    print "[%.3f] Success." \
          % (clock() - prog_start)
    raw_input("Press any enter to exit")