# -*- coding: utf-8 -*- """ Created on Wed Dec 13 13:40:47 2017 Base VISA driver @author: mbuel """ import visa import time # StartVoltage = 10 global rm rm = visa.ResourceManager() global rmList rmList = rm.list_resources() #Find all VISA resources #Private - completed by class #def _GetResourceList(): # global rmList # try: # #raise Exception('Test Resource fault') #used for test purposes # rmList = rm.list_resources() # return rmList # except: # return rmList # Used for Fluke45 (possibly 8845A) should probably be moved to that object # In process of deprecating #def __SerialReadLoop(resource, termChar): # returnString = "" # while (termChar not in returnString): # returnString += resource.read() # return returnString #generic reader #resource - VISA resource being written/read from #command - only required if you are iterating - command to send to resource #iterations=1 - if not sent, one measurement is taken and sent back (single) #iteration > 1 - if set to greater than 1, it will return an array of data points #prompt="" - default, don't look or wait for prompt #prompt="=>" - if set, it writes to the resource, then waits for the prompt #return data - for single point #return dataSet - for array of points def ReadData(resource, command="", iterations=1, prompt=""): '''Generic visa reader function. resource: VISA resource being read from instrument. command: required only if iterations (looped measurement). iterations: defaults to 1, if more than 1 command is required. prompt: required with certain instruments to stop read loop.''' try: data = "" dataSet = [] # print ("Before Counter") # print ("iterations: " + str(iterations)) # print ("Command: " + command) if iterations > 1 and len(command)>1: while (iterations >= 1): # print ("Inside for loop") WriteData(resource, command) if len(prompt)>1: #WriteData(resource, command) while prompt not in data: WriteData(resource,command) data += resource.read() data = data.split("/r/n")[1] else: WriteData(resource, command) data = resource.read() dataSet.append(data) iterations = iterations - 1 else: if len(prompt)>1: #WriteData(resource, command) data += resource.read() data = data.split("/r/n")[1] else: data = resource.read() dataSet.append(data) # print data except: dataSet = None #VISA TIMEOUT ERROR return dataSet #generic writer #resource - VISA resource being written to #command - command to write to VISA port #no return def WriteData(resource, command): '''Generic VISA writer. resource: VISA resource. command: command to send.''' try: resource.write(command) time.sleep(0.2) except: print("Unable to write to specified resource.") # Used to connect to resource from global filtering on instrument identifier # instIdentifier - string to compare to device output, makes sure you are grabbing the correct resource # command - command sent to device to return data # instFilter - is used to make sure you don't connect to the same instrument twice. Used for Dmm1, Dmm2 most frequently # prompt - if the device communicates slower, using this to loop until prompt is received can make sure correct data is returned. # test coverage completed # returns resource that is used to connect to the device def GetInstrument(instIdentifier, command, instFilter="Z", prompt=""): '''Used to connect to resource from global rmList defined. instIdentifier: Instrument string to filter on. command: command to query instrument with. instFilter: defaults to "Z" to skip, if you have two of the same types of isntruments this is used. prompt: used to end readLoop on older instruments.''' global rmList resource = None if instIdentifier == "" or command == "": print("Cannot continue without proper instIdentifier or iDcommand") return resource else: for resource in rmList: #print (resource) instString = "" try: newResource = OpenInstrument(resource) if ("ASRL" not in resource): WriteData(newResource, command) instString = ReadData(newResource) else: if prompt is not "": WriteData(newResource, command) instString = ReadData(newResource, 1, prompt) print instString if instIdentifier in str(instString[0]): if str(instFilter) in str(newResource ): continue else: return resource except Exception as e: #Handle error? print ("exception: " + str(e)) resource = "" finally: CloseInstrument(resource) print resource return resource def OpenInstrument(resource): '''Open VISA resource.''' internalResource = "" if str(resource) is not "": internalResource = rm.open_resource(resource, send_end=True) internalResource.write_termination = '\r\n' # if "ASRL" in resource: # internalResource = rm.open_resource(resource, send_end=True) # internalResource.write_termination = '\r' # else: # internalResource = rm.open_resource(resource, send_end=False) return internalResource else: return internalResource def CloseInstrument(resource): '''CloseInstrument - closes the VISA resource''' try: if "Instrument" in str(resource): rm.close return True else: return False except: return False #TEST FUNCTIONS #Error handler returns false, if IDN fails for any reason #May Deprecate this function def VerifyInstrument(resource, command): '''VerifyInstrument - verifies communications on VISA resource.''' try: #print (Instrument) #print (Instrument.query("*IDN?")) return len(resource.query(command)) > 0 except: return False #Used for internal system testing def InternalTest(): '''Used for internal system testing.''' if (True): PowerSupplyResource = GetInstrument("SPD","*IDN?") print PowerSupplyResource PowerSupply = OpenInstrument(PowerSupplyResource) #if (VerifyInstrument(PowerSupply)): # print(PowerSupply.query_ascii_values('*IDN?')) # PowerSupply ("INST CH1") #Select on Ch 1 # SetVoltage = "CH1:VOLT %f" %StartVoltage Dmm1Resource = GetInstrument("DM3R","*IDN?") # print(Dmm1Resource) Dmm1 = OpenInstrument(Dmm1Resource) #if (VerifyInstrument(Dmm1)): #Dmm1.query(':measure:voltage:dc:measure:auto;') #time.sleep(0.2) #print(Dmm1.read()) Dmm2Resource = GetInstrument("DM3R","*IDN?", Dmm1) # print(Dmm2Resource) #print (str(PowerSupply)) SetVoltage = "CH1:VOLT 15.0" SetCurrent = "CH1:CURRENT 0.2" #print(PowerSupply) try: # print(PowerSupply) WriteData(PowerSupply, SetVoltage) #time.sleep(0.2) print("Wrote Supply Voltage.") #debug line WriteData(PowerSupply, SetCurrent) #time.sleep(0.2) print("Wrote Supply Current.") #debug line EnableSupply = "OUTPUT CH1,ON" WriteData(PowerSupply, EnableSupply) #Turn on Ch1 #time.sleep(0.2) WriteData(PowerSupply,"*IDN?") print(ReadData(PowerSupply)) CloseInstrument(PowerSupply) except: print("Problem with Power Supply.") ## #PowerSupply.write(SetVoltage) #Set voltage to 'SetVoltage' #PowerSupply.write("*IDN?") #print(PowerSupply.readline()) #PowerSupply.write("MEAS:VOLT? CH1") ##print(PowerSupply. ()) #print(CloseInstrumentResource(PowerSupply)) # # print Dmm1 #Dmm1.write_termination = '\r' #Dmm1.write("MEAS?") #print (SerialReadLoop(Dmm1,"=>")) #CloseInstrument(Dmm1) else: print("cannot capture list of resources.") #print (CloseInstrumentResource(Dmm1)) #initialize the class #_GetResourceList() #InternalTest()