from qolab.hardware.basic import BasicInstrument from qolab.hardware.power_supply import PowerSupplySCPI import time class KeysightE3612A(PowerSupplySCPI): """ Keysight E3612A power supply """ def __init__(self, resource, *args, **kwds): super().__init__(resource, *args, **kwds) self.resource.read_termination='\n' self.config['Device model'] = 'Keysight E3612A' self.numberOfChannels = 3 self.deviceProperties = {'OpMode', }; self.channelProperties = {'IsOn', 'Regulation', 'Vout', 'Vlimit', 'Iout', 'Ilimit', 'dV', 'dI', } self.deffaultChannelR = 47; # used if no empirical way to calculate it via Vout/Iout def getChandV(self, chNum): """ Voltage precision per channel. Obtained from data sheet. Alternative estimate is by assuming 14 bit precision from the maximum reading. """ if chNum == 1: return 0.24e-3 return 1.5e-3 def getChandI(self, chNum): """ Current precision per channel. Obtained from data sheet. Alternative estimate is by assuming 14 bit precision from the maximum reading. """ if chNum == 1: return 0.2e-3 return 0.160e-3 # see specification for high current > 20mA def getOpMode(self): """ Queries power supply operation mode, returns OFF|PAR|SER|TRAC OFF stands for independent channels """ qstr = f'OUTP:PAIR?' rstr = self.query(qstr) return( rstr ) def setOpMode(self, val): """ Sets power supply operation mode, returns OFF|PAR|SER|TRAC OFF stands for independent channels """ cmnd = f'OUTP:PAIR {val}' rstr = self.write(cmnd) def setChanOn(self, chNum): """ Power up channel output """ self.write(f'OUTP ON,(@{chNum})') def setChanOff(self, chNum): """ Power down channel output """ self.write(f'OUTP OFF,(@{chNum})') @BasicInstrument.tsdb_append def getChanIsOn(self, chNum): """ Queries channel output state """ qstr = f'OUTP? (@{chNum})' rstr = self.query(qstr) return( bool(float(rstr)) ) @BasicInstrument.tsdb_append def getChanRegulation(self, chNum): """ Queries channel output regulation 0 - The output is off and unregulated 1 - The output is CC (constant current) operating mode 2 - The output is CV (constant voltage) operating mode 3 - The output has hardware failure """ qstr = f'STAT:QUES:INST:ISUM{chNum}:COND?' rstr = self.query(qstr) return( int(rstr) ) @BasicInstrument.tsdb_append def getChanVout(self, chNum): qstr = f'MEAS:VOLT? (@{chNum})' rstr = self.query(qstr) return( float(rstr) ) @BasicInstrument.tsdb_append def getChanVlimit(self, chNum): qstr = f'SOUR:VOLT? (@{chNum})' rstr = self.query(qstr) return( float(rstr) ) @BasicInstrument.tsdb_append def setChanVlimit(self, chNum, val): if chNum == 1 and val > 6.180: val = 6.180 if (chNum == 2 or chNum == 3) and val > 25.750: val = 25.750 cmnd = f'SOURCe:VOLT {val},(@{chNum})' rstr = self.write(cmnd) @BasicInstrument.tsdb_append def getChanIout(self, chNum): qstr = f'MEAS:CURR? (@{chNum})' rstr = self.query(qstr) return( float(rstr) ) def setChanIout_mA(self, chNum, val, **kwds): """ Set current in mA. Calls setChanIout with val converted from mA to A """ return self.setChanIout(chNum, val/1000.0, **kwds) @BasicInstrument.tsdb_append def setChanIout(self, chNum, val, currentHeadRoom=1e-3, dwellTime=0.3): """ Tuning Vout to achieve desired Iout. Generally setting current limit will maintain current near but not exact to desired. Since Vlimit can be set with good precision, this function will try tune Vlimit until the Idesired is reached. """ iDesired = val # self.setChanIlimit(chNum, val+currentHeadRoom) # Here, we assume that hook up is already made, so we can estimate source resistance # So the protocol is the following: # find R -> calculate required Vout for the desired Idesired # -> set Vlimit to reach desired Vout and Iout # In general, once we estimate resistance of the load + source, we do not need to # anything extra. But there is a problem: for a given Vlimit setting, the actual Vout # is slightly off. # We will assume that Vlimit = R*Iout + Vo = Vout + Vo, i.e. linear approximation for i in range(10): iOut=self.getChanIout(chNum) if abs(iOut-iDesired) <= self.getChandI(chNum): break vOut=self.getChanVout(chNum) if self.getChanRegulation(chNum) == 2: # i.e. CV mode vLimit=self.getChanVlimit(chNum) Vo = vLimit - vOut else: Vo=0 if (iOut == 0) or (vOut <= 0.001): # when vOut set to 0 the numbers are misreported R = self.deffaultChannelR # some default else: R=vOut/iOut vDesired = R*iDesired self.setChanVlimit(chNum, vDesired+Vo) time.sleep(dwellTime) @BasicInstrument.tsdb_append def getChanIlimit(self, chNum): qstr = f'SOURce:CURR? (@{chNum})' rstr = self.query(qstr) return( float(rstr) ) @BasicInstrument.tsdb_append def setChanIlimit(self, chNum, val): """ Set current limit, seems to be >=0.002 for Ch1 and >=0.001 for Ch2 and Ch3 """ if chNum == 1 and val < 0.002: val = 0.002 if chNum == 1 and val > 5.150: val = 5.150 if (chNum == 2 or chNum == 3) and val < 0.001: val = 0.001 if (chNum == 2 or chNum == 3) and val > 1.030: val = 1.030 cmnd = f'SOURCe:CURR {val},(@{chNum})' rstr = self.write(cmnd) if __name__ == '__main__': import pyvisa print("testing") rm = pyvisa.ResourceManager() print(rm.list_resources()) instr=rm.open_resource('USB0::10893::4354::MY61001869::0::INSTR') ps = KeysightE3612A(instr) print('------ Header start -------------') print(str.join('\n', ps.getHeader())) print('------ Header ends -------------')