How to build an XBee Hex Long address in Python

Question

I am trying to build an XBee dest_addr_long (Hex address of the XBee) but I keep getting error

ValueError: The data provided for 'dest_addr_long' was not 8 bytes long

I have tried the example:

device={
         "CO3":'\x00\x13\xa2\x00\x40\x52\x8d\x8a'
}

and this works, but I don't know the address until the device shows up on my PAN and then I get the address and store it in a database and change the Node ID.

Here is my code and how I am trying to generate the XBee Address

xbee_source_addr_long = xbee_packet['source_addr_long']
        source_addr_long= ''.join(x.encode('hex') for x in xbee_source_addr_long)
        xbee_source_addr_long_hex = (r"\x" + str(source_addr_long [0:2]) + 
             r"\x" + str(source_addr_long [2:4]) +
             r"\x" + str(source_addr_long [4:6]) +
             r"\x" + str(source_addr_long [6:8]) +
             r"\x" + str(source_addr_long [8:10]) +
             r"\x" + str(source_addr_long [10:12]) +
             r"\x" + str(source_addr_long [12:14]) +
             r"\x" + str(source_addr_long [14:16]))

This gives me a string in the correct format but the len is 32.

Question: How can I take the source_addr_long and generate a readable string that has a len of 8 and looks like this \x00\x13\xa2\x00\x40\x52\x8d\x8a

Answer 1

Take a look at Python's struct.pack() function. It can convert your array of values into a packed structure of bytes.

If you're going to be using XBee modules from Python, you might want to try the Open Source python-xbee library.

Something like:

struct.pack( "BBBBBBBB",
    xbee_source_addr_long[0],
    xbee_source_addr_long[1],
    xbee_source_addr_long[2],
    xbee_source_addr_long[3],
    xbee_source_addr_long[4],
    xbee_source_addr_long[5],
    xbee_source_addr_long[6],
    xbee_source_addr_long[7]);

Note that I'm not a Python programmer, so there might be an easier way to pull that off.

Answer 2

This post can solve your problem .

Assume, you are having following scenario .

source_addr  = ['0x8f', '0x18']

source_addr_long =  ['0x00', '0x13', '0xa2', '0x00', '0x40', '0xb5', '0xad', '0x6e']


# Coordinator transmit packet to any router .

# Decision  can be taken at run time by  coordinator.

# One to many nodes transmission is thus possible.

xbee1.tx
(
      frame='0x1' 
    , dest_addr=bytearray( int(x,16) for  x in source_addr)
    , data='Hi' 
    , dest_addr_long= bytearray( int(x,16) for  x in source_addr_long)
)

# It will Work . Go to very basic thing .

# string to int , int to hex , hex to int .

#  hex(19) => '0x13'
#  int('0x13',16)  => 19

#  x = '0x13' 
# then int(x,16) will be 19