1

import ctypes

     3

     4

LPC_STATUS={0x01 : "Started",

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            0x02 : "Stopped"}

     6

     8

    def HandleTransaction(self, transaction):

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        self.TransactionLock.acquire()

    10

        try:

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            transaction.SetPseudoFile(self.serialPort)

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            # send command, wait ack (timeout)

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            transaction.SendCommand()

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            current_plc_status = transaction.GetCommandAck()

    15

            if current_plc_status is not None:

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                res = transaction.ExchangeData()

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            else:

    19

        finally:

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            self.TransactionLock.release()

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        return LPC_STATUS.get(current_plc_status,"Broken"), res

    22

    24

    def __init__(self, command, optdata = ""):

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        self.Command = command

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        self.OptData = optdata

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        self.pseudofile = None

    28

    29

    def SetPseudoFile(self, pseudofile):

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        self.pseudofile = pseudofile

    31

    32

    def SendCommand(self):

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        # send command thread

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        self.pseudofile.write(chr(self.Command))

    35

    36

    def GetCommandAck(self):

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        res = self.pseudofile.read(2)

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        if len(res) == 2:

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            comm_status, current_plc_status = map(ord, res)

    40

        else:

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        # LPC returns command itself as an ack for command

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        if(comm_status == self.Command):

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            return current_plc_status

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        return None 

    46

    47

    def SendData(self):

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        length = len(self.OptData)

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        # transform length into a byte string

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        # we presuppose endianess of LPC same as PC

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        lengthstr = ctypes.string_at(ctypes.pointer(ctypes.c_int(length)),4)

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        buffer = lengthstr + self.OptData

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        return self.pseudofile.write(buffer)

    54

    55

    def GetData(self):

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        lengthstr = self.pseudofile.read(4)

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        # transform a byte string into length 

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        length = ctypes.cast(ctypes.c_char_p(lengthstr), ctypes.POINTER(ctypes.c_int)).contents.value

    59

        return self.pseudofile.read(length)

    60

    61

    def ExchangeData(self): 

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        pass

    63

    65

    def __init__(self):

    67

    69

    def __init__(self):

    71

    73

    def __init__(self):

    75

    81

    def __init__(self, data):

    84

    86

    def __init__(self):

    89

    91

    def __init__(self):

    94

    95

if __name__ == "__main__":

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#    TestConnection.HandleTransaction(GET_PLCIDTransaction())

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    TestConnection.HandleTransaction(STARTTransaction())

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#    TestConnection.HandleTransaction(SET_TRACE_VARIABLETransaction(

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#           "\x03\x00\x00\x00"*200))

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#    TestConnection.HandleTransaction(STARTTransaction())

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    while True:

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        TestConnection.HandleTransaction(SET_TRACE_VARIABLETransaction(

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           "\x01\x00\x00\x00"+

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           "\x04"+

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           "\x01\x02\x02\x04"+

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           "\x01\x00\x00\x00"+

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           "\x08"+

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           "\x01\x02\x02\x04"+

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           "\x01\x02\x02\x04"+

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           "\x01\x00\x00\x00"+

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           "\x04"+

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           "\x01\x02\x02\x04"))

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    #status,res = TestConnection.HandleTransaction(GET_TRACE_VARIABLETransaction())

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    #print len(res)

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    #print "GOT : ", map(hex, map(ord, res))

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    #TestConnection.HandleTransaction(STOPTransaction())