Controlling SP2150i monochromator with Python/PyVisa

"""
@author: Bala Krishna Juluri
"""

from visa import *
import time
#assumes connected with USB. Drivers are installed. Needs pyvisa for communication.
# There is no need to use visa write command for SP2150. because all commands are ask type (you write something and get a confirmation back saying OK)
# filter 1 is no filter
# filter 2 is in 320 nm long pass filter
# filter 3 is 590 long pass filter cutoff
# filter 4 is 715 long pass filter
# filter 5 is 1250 long pass filter
#filter 6 is block

class SP2150i():
    def __init__(self):
        #self.m=instrument(get_instruments_list()[0])
        try:
            print get_instruments_list()
            self.m=instrument('COM7', timeout = 10) #he default timeout is 5 sec, change the timeout if needed
        except:
            print "Check if monochromotor is connected to right COM port of instrument list (see control panel, hardward devices). Cannot connect to monochromator. Check connection. Check drivers"

    def get_nm(self):
        self.curr_nm=self.m.ask_for_values('?NM')
        return self.curr_nm

    def get_nm_per_min(self):
        self.curr_nm_min=self.m.ask_for_values('?NM/MIN')
        return self.curr_nm_min

    def get_serial_model(self):
        self.serial_no=self.m.ask_for_values('SERIAL')
        self.model_no=self.m.ask_for_values('MODEL')
        return self.serial_no,self.model_no

    def goto_nm_max_speed(self,nm):
        self.m.ask('%0.2f GOTO' % nm)

    def get_turret(self):
        self.turret=self.m.ask_for_values('?TURRET')
        return self.turret

    def get_filter(self):
        self.filter=self.m.ask_for_values('?FILTER')
        time.sleep(2)
        return self.filter

    def get_grating(self):
        self.grating=self.m.ask_for_values('?GRATING')
        return self.grating

    def set_turret(self,num):
        if num <=2:
            self.m.ask(str(int(num))+ ' TURRET')
        else:
            print "There is not turret with this input"

    def set_filter(self,num):
        if num <=6:
            self.m.ask(str(int(num))+ ' FILTER')
            print "Filter changed and waiting with additional delay..."
            time.sleep(1) # Additional delay, just in case.
            print "Done waiting"
        else:
            print "There is no filter with this input"

    def set_grating(self,num):
        if num<=2:
            self.m.ask(str(int(num))+ ' GRATING')
            #time.sleep(5) # Additional delay, just in case
        else:
            print "There is no grating with this input"


    def goto_nm_with_set_nm_per_min(self,nm,nm_per_min):
       self.m.ask('%0.2f NM/MIN' % nm_per_min)
       self.m.ask('%0.2f >NM' % nm)
       char=0
       while char!=1:
           s=self.m.ask('MONO-?DONE')
           char=int(s[2])
           #print "Current wavelength is "+ self.m.ask('?NM')
           time.sleep(.2)
       print "Scan done?: "+'yes' if char == 1 else 'No'
       self.m.ask('MONO-STOP')
       return self.m.ask_for_values('?NM')

if __name__ == "__main__":
    #This part of the codes uses the SP2150i class to do a wavelength scan
    a=SP2150i()
    print a.get_serial_model()
    print a.get_grating()
    print a.get_filter()
    print a.get_nm_per_min()
    print a.get_nm()
    a.set_grating(2) # can only take 1 or 2 as input

    start_wave=500
    end_wave=1000
    delta_wave=20
    speed_nm_per_min=2000
    a.set_filter(2) # this applies the 320 nm filter in the beginning
    for i in xrange(start_wave,end_wave,delta_wave):
        print "----------------------------"
        print "Wavelength input is %0.2f nm" % i
        wave=a.goto_nm_with_set_nm_per_min(i,speed_nm_per_min)

        if i <= 370 and i+delta_wave >= 370:
            a.set_filter(2)

        if i <= 660 and i+delta_wave >= 660:
            a.set_filter(3)

        if i <= 775 and i+delta_wave >= 775:
            a.set_filter(4)

        if i <= 1300 and i+delta_wave >= 1300:
            a.set_filter(5)

        print "Wavelength output is "+str(wave[0])+ " nm"
        print "----------------------------"

    print "Resetting the monochromator to home position"
    a.goto_nm_max_speed(400)
    a.set_filter(1)
    print "Position to home at  " + str(a.get_nm()[0]) + " nm"+ ' and filter has been reset to ' + str(a.get_filter()[0])
    print "Monochromator scan done. Have a nice day!"