View difference between Paste ID: VpZVuw0t and KEr1hZW9

 # Fabio Eboli 01-2013
-# functions to connect to FE5680A
+# functions useful for connecting to FE5680A
 # usage:
 # p=SetPort(portnumber)  note the in windows 0 is COM1, 1 is COM2 etc
 # value=GetOffs(p)
 # SetOffsRam(p,1000) 1000 is the new momentary offset
 # SetOffsRelRam(p,-30) the new momentary offset s 30 units less than last one i.e. 970
 # StoreOffsEE(p) stores the actual momentary offset into EEPROM
 # SetOffsEE(p,500) 500 is the new offset, and is permanently saved into EEPROM
 # ChangeFreqHz(p,1) move the output frequency 1Hz high
 # ChangeFreqP(p,-2.5e-10) move the output frequency -2.5x10^-10
 # SendCommandChar(p,0x22,'',True) check and print in readable format the result of 0x2D command
 
 import serial
 from struct import *
 import time
 
 lastcommandtime=0
 resolution_parts_per_bit=6.80789e-13
 
 # prepares the communication serial port to the FE5680A
 # portno is the port number, in win 0 for COM1 etc
 # returns the port that will be passed to the other functions
 def SetPort(portno):
     global lastcommandtime
     port=serial.Serial(portno)
     print("Connected to "+port.name)
     port.baudrate=9600
     port.timeout=.1
     port.close()
     lastcommandtime=time.time()
     return port
 
 # builds and sends a command to the FE5680A
 # port : serial port returned by SetPort()
 # ID : command code number
 # Data : command data, string
 # ReadBack : True if an answer from the FE5680A is expected
 # Returns : [rtncode,rtndata,error]
 # rtncode: -1 error in answer
 #          0 no answer expected
 #          1 correct answer received
 # rtndata: payload data returned from FE5680A, binary string
 # error: error description
 def SendCommand(port,ID,Data,ReadBack):
     global lastcommandtime
     IDstring=pack('B',ID)
     datalen=len(Data)
     if datalen>128:
         return -1
     if len(Data)>0:
         totlen=datalen+5 # total message lenght ID+Lenght(2)+Checksum1+Data Lenght+Checksum2
     else:
         totlen=datalen+4
     totlenstr=pack('<H',totlen)
     cs1str=pack('B', (ID ^ (unpack('B',totlenstr[0])[0]) ^ (unpack('B',totlenstr[1])[0])))
     cs2=0
     for chars in Data:
         cs2 ^= unpack('B',chars)[0]
     cs2str=pack('B',cs2)
 
     timefromlastcommand=(time.time())-lastcommandtime
     while timefromlastcommand<2: #wait at least 2s between communications to FE5680A
         timefromlastcommand=(time.time())-lastcommandtime
     port.open()
     port.write(IDstring+totlenstr+cs1str+Data+cs2str)
 #    print(IDstring+totlenstr+cs1str+Data+cs2str)
     ret=[0,'','']
     if ReadBack==True:
         answer=port.readall()
 #        answer=input("Answer? ")
         ansID=unpack('B',answer[0])[0]
         anslen=unpack('<H',answer[1:3])[0]
         anscs1=unpack('B',answer[3])[0]
         calccs2=0
         #check command code
         if ansID == ID:
             #check total lenght
             if len(answer) == anslen:
                 #check command checksum
                 calccs1=(unpack('B',answer[0])[0]) ^ (unpack('B',answer[1])[0]) ^ (unpack('B',answer[2])[0])
                 if anscs1 == calccs1:
                     anscs2=unpack('B',answer[anslen-1])[0]
                     # calculate data checksum
                     for d in answer[4:anslen-1] :
                         calccs2^=unpack('B',d)[0]
                     #check data checksum
                     if anscs2 == calccs2 :
                         ret=[1,answer[4:anslen-1],"No Errors"]
                     else:
                         ret=[-1,answer[4:anslen-1],"Error: wrong data checksum"]
                 else:
                     ret=[-1,answer[4:anslen-1],"Error: wrong command checksum"]
             else:
                 ret=[-1,answer[4:anslen-1],"Error: wrong packet lenght"]
         else:
             ret=[-1,'',"Error: bad command code returned"]
     port.close()
     lastcommandtime=time.time()
     return  ret
 
 # Same as SendCommand but returns the payload in readable string format
 # and prints on stdout
 def SendCommandChar(port,ID,Data,ReadBack):
     answer=SendCommand(port,ID,Dara,ReadBack)
 #    answer=input("Answer? ")
     answerstring=''
     for i in answer[1]:
         answerstring+=(hex(unpack('B',i)[0]))+ "\r\n"
     print(str(len(answer[1]))+" Elements in answer")
     print(answerstring)
     return [answer[0],answerstring,answer[2]]
 
 
 # Returns the Offset from the FE5680A
 def GetOffs(port):
     commandcode=0x2D
     data=''
     ret=SendCommand(port,commandcode,data,True)
     if ret[0]==1:
         return unpack('>i',ret[1])[0]
     else:
         print("Error code "+str(ret[0]))
         print(ret[2])
         return 0
 
 # Sets the offset, without saving the value
 def SetOffsRam(port,value):
     commandcode=0x2E
     data=pack('>i',value)
     return SendCommand(port,commandcode,data,False)[2]
 
 # Sets the offset relative to the value stored in the FE5680A,
 # without saving the value, useful for incremental changes
 def SetOffsRelRam(port,value):
     refoffs=GetOffs(port)
     newoffs=refoffs+value
     return SetOffsRam(port,newoffs)
 
 # Sets the offset, saving the value into the EEPROM of the FE5680A
 def SetOffsEE(port,value):
     commandcode=0x2C
     data=pack('>i',value)
     return SendCommand(port,commandcode,data,False)
 
 # Reads the offset from internal ram and Stores it to EEPROM
 def StoreOffsEE(port):
     value=GetOffs(port)
     return SetOffsEE(port,value)
 
 # Change the frequency output of valueHz Hz, not stored
 def ChangeFreqHz(port,valueHz):
     Offs=int(float(valueHz)/(resolution_parts_per_bit*1e7))
     print("new offset: "+str(Offs))
     return SetOffsRelRam(port,Offs)
 
 # Change the frequency output of valueP parts, not stored
 def ChangeFreqP(port,valueP):
     Offs=int(float(valueP)/resolution_parts_per_bit)
     print("Offset: "+str(Offs))
     return SetOffsRelRam(port,Offs)