sharem

PYthon _CAN

Discussion created by sharem on Apr 2, 2014
Latest reply on Apr 2, 2014 by recurvata
Hi every one,
I am new to this python programming.
Recently, I have started working with python programming to communicate with PCAN-usb.
I was able to Initialize PCAN, write message but i am unable to receive the data from it.
__________________________
but while using the PCAN view I am able to write and read the data but not with python programming.
I am expecting the following data when a particular message is send as shown below.
[ATTACH=CONFIG]32727[/ATTACH]
____________________________________________
can you please help out to fix this issue in my programming.
                                                  
                                                         Thankingyou

_____________________________________________________________________________________________________________
import pycan.drivers.canusb as driver
from pycan.common import CANMessage
from ctypes import *
_____________________________________________________________________________________________________
# Represents a PCAN message
class TPCANMsg (Structure):
    """
    Represents a PCAN message
    """
    _fields_ = [ ("ID",c_ulong),  ("MSGTYPE", TPCANMessageType), ("LEN",     c_ubyte),("DATA",    c_ubyte * 8) ] 
____________________________________________________________________________________________________
class TPCANTimestamp (Structure):
    """
    Represents a timestamp of a received PCAN message
    Total Microseconds = micros + 1000 * millis + 0xFFFFFFFF * 1000 * millis_overflow
    """
    _fields_ = [ ("millis", c_ulong),("millis_overflow", c_ushort),("micros", c_ushort) ]
---------------------------------------------------------------------------------------------------------------------
#///////////////////////////////////////////////////////////
# PCAN-Basic API function declarations
#///////////////////////////////////////////////////////////

# PCAN-Basic API class implementation
#
class PCANBasic:
    """
      PCAN-Basic API class implementation
    """     
    def __init__(self):
        # Loads the PCANBasic.dll
        #    
        self.__m_dllBasic = windll.LoadLibrary("PCANBasic")
        if self.__m_dllBasic == None:
            print "Exception: The PCAN-Basic DLL couldn't be loaded!"

    # Initializes a PCAN Channel
    #
    def Initialize(self,Channel,Btr0Btr1,HwType = TPCANType(0),IOPort = c_uint(0),Interrupt = c_ushort(0)):
       
        """             
        Returns:
          A TPCANStatus error code
        """
        try:
            res = self.__m_dllBasic.CAN_Initialize(Channel,Btr0Btr1,HwType,IOPort,Interrupt)
            return TPCANStatus(res)
        except:
            print "Exception on PCANBasic.Initialize"
            raise
       
    #  Uninitializes one or all PCAN Channels initialized by CAN_Initialize
    #
    def Uninitialize(self,Channel):

        """     
        Returns:
          A TPCANStatus error code
        """
        try:
            res = self.__m_dllBasic.CAN_Uninitialize(Channel)
            return TPCANStatus(res)
        except:
            print "Exception on PCANBasic.Uninitialize"
            raise


#  Resets the receive and transmit queues of the PCAN Channel
#
    def Reset(self,Channel):

        """
Returns:
          A TPCANStatus error code
        """
        try:
            res = self.__m_dllBasic.CAN_Reset(Channel)
            return TPCANStatus(res)
        except:
            print "Exception on PCANBasic.Reset"
            raise
# Retrieves a PCAN Channel value
#
    def GetValue(self,Channel,Parameter):

        """
Returns:
          A touple with 2 values
        """       
        try:
            if Parameter == PCAN_API_VERSION or Parameter == PCAN_HARDWARE_NAME or Parameter == PCAN_CHANNEL_VERSION or Parameter == PCAN_LOG_LOCATION or Parameter == PCAN_TRACE_LOCATION:
                mybuffer = create_string_buffer(256)
            else:
                mybuffer = c_int(0)

            res = self.__m_dllBasic.CAN_GetValue(Channel,Parameter,byref(mybuffer),sizeof(mybuffer))
            return TPCANStatus(res),mybuffer.value
        except:
            print "Exception on PCANBasic.GetValue"
            raise           
    #  Gets the current status of a PCAN Channel
    #
    def GetStatus(self,Channel):

        """
          Gets the current status of a PCAN Channel
         
        Parameters:
          Channel  : A TPCANHandle representing a PCAN Channel
       
        Returns:
          A TPCANStatus error code
        """
        try:
            res = self.__m_dllBasic.CAN_GetStatus(Channel)
            return TPCANStatus(res)
        except:
            print "Exception on PCANBasic.GetStatus"
            raise
       
    def Read(self,Channel):

        """
          Reads a CAN message from the receive queue of a PCAN Channel

        Remarks:
          The return value of this method is a 3-touple, where
          the first value is the result (TPCANStatus) of the method.
          The order of the values are:
          [0]: A TPCANStatus error code
          [1]: A TPCANMsg structure with the CAN message read
          [2]: A TPCANTimestamp structure with the time when a message was read
         
        Parameters:
          Channel  : A TPCANHandle representing a PCAN Channel
       
        Returns:
          A touple with three values
        """
        try:
            msg = TPCANMsg()
            timestamp = TPCANTimestamp()
            print "inner function:-", msg
            res = self.__m_dllBasic.CAN_Read(Channel,byref(msg),byref(timestamp))
            return TPCANStatus(res),msg,timestamp
        except:
            print "Exception on PCANBasic.Read"
            raise          

    # Transmits a CAN message
    #
    def Write(self,Channel,MessageBuffer):

        """
          Transmits a CAN message
         
        Parameters:
          Channel      : A TPCANHandle representing a PCAN Channel
          MessageBuffer: A TPCANMsg representing the CAN message to be sent
       
        Returns:
          A TPCANStatus error code
        """
        try:
            res = self.__m_dllBasic.CAN_Write(Channel,byref(MessageBuffer))
            return TPCANStatus(res)
        except:
            print "Exception on PCANBasic.Write"
            raise
        
    def GetErrorText(self,Error,Language = 0):

        """
          Configures or sets a PCAN Channel value

        Remarks:

          The current languages available for translation are:
          Neutral (0x00), German (0x07), English (0x09), Spanish (0x0A),
          Italian (0x10) and French (0x0C)         

          The return value of this method is a 2-touple, where
          the first value is the result (TPCANStatus) of the method and
          the second one, the error text
         
        Parameters:
          Error    : A TPCANStatus error code
          Language : Indicates a 'Primary language ID' (Default is Neutral(0))
       
        Returns:
          A touple with 2 values
        """ 
        try:
            mybuffer = create_string_buffer(256)
            res = self.__m_dllBasic.CAN_GetErrorText(Error,Language,byref(mybuffer))
            return TPCANStatus(res),mybuffer.value
        except:
            print "Exception on PCANBasic.GetErrorText"
            raise

#____________________________________________________________________________________________________________
if __name__ == '__main__':
   
    msg = TPCANMsg()
    tmstamp = TPCANTimestamp()
    data = 0x22,0xF1,0x51
    msg._fields_ = [ ("ID",0x602),("MSGTYPE", PCAN_MESSAGE_STANDARD),("LEN",    3),("DATA", data) ]

#______________________________________________________________________________________________  
#----------------Initializ---------------------------  
#_______________________________________________________________________________________________   

    can = PCANBasic()
    result = can.Initialize(PCAN_USBBUS1, PCAN_BAUD_500K)
    if result == PCAN_ERROR_OK:
        print "Getstatus:-",can.GetStatus(PCAN_USBBUS1)
#______________________________________________________________________________________________
#--------------Writing/Sending _data------------------
#______________________________________________________________________________________________     
        wrtstat= can.Write(PCAN_USBBUS1,msg)
        if (wrtstat == PCAN_ERROR_OK):
            print "Message was sent"
        else:
            print "Error Occured during writing"
           
#__________________________________________________________________________________________________    
#-------------Reading----------------------------------
#_________________________________________________________________________________________________           
        status = PCAN_ERROR_QRCVEMPTY     
        print "beforeloop:-",status       
        while (status != PCAN_ERROR_OK ):
           
            status,msg,time = can.Read(PCAN_USBBUS1)
            can.FilterMessages(PCAN_USBBUS1, 0x400, 0x580, PCAN_MESSAGE_STANDARD)
            print "inside loop:-", status
            if (status == PCAN_ERROR_OK):
                print "Message received"   
#__________________________________________________________________________________________________
           
    else:
        print "Init error!"
       
    print "End"
    can.Uninitialize(PCAN_USBBUS1)

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