is there a problem on this simple code

[jrlen balane]

basically what the code does is transmit data to a hardware and then
receive data that the hardware will transmit.

import serial
import string
import time
from struct import *


ser = serial.Serial()

ser.baudrate = 9600
ser.port = 0
ser
ser.close()
ser.open()

command = 67
message_no = 1
total_data = 2

item = 12000                            #to warm-up the hardware
hexed = hex(item)
data_hi, data_lo = divmod(item, 0x100)
checksum = -(data_hi + data_lo + 0x46) & 0xff
ser.write(pack('6B', command, message_no, total_data, data_lo,
data_hi, checksum)) #serial transmit protocol
time.sleep(1)

item = 10000
no = 0
for item in range(10000, 30001, 250):
    no = no +1
    hexed = hex(item)
    data_hi, data_lo = divmod(item, 0x100)
    checksum = -(data_hi + data_lo + 0x46) & 0xff
    ser.write(pack('6B', command, message_no, total_data, data_lo,
data_hi, checksum))
    data = ser.read(10)
    (command, msg_no, no_databyte, temp1, temp2, pyra1, pyra2,
voltage, current, checksum) = unpack('10B', data)  #serial receive
protocol
    print no, command, msg_no, no_databyte, temp1, temp2, pyra1,
pyra2, voltage, current, checksum
    time.sleep(1)

ser.close()


===========================
and here is some result after running the program on Idle Python 2.3
(enthought ed.)

1 70 168 6 0 0 0 0 0 0 12
2 70 2 6 0 0 0 0 0 0 178
3 70 3 6 0 0 0 0 0 0 177
4 70 4 6 0 0 0 0 0 0 176
5 70 5 6 0 0 0 0 0 0 175
6 70 6 6 0 0 0 0 0 0 174
7 70 7 6 0 0 0 0 0 0 173
8 70 8 6 0 0 0 0 0 0 172
9 70 9 6 0 0 0 0 0 0 171
10 70 10 6 0 0 0 0 0 0 170
11 70 11 6 0 0 0 0 0 0 169
12 70 12 6 0 0 0 0 0 0 168
13 70 13 6 0 0 0 0 0 0 167
14 70 14 6 0 0 0 0 0 0 166
15 70 15 6 0 0 0 0 0 0 165

==========================

the result i am expecting is for the data bytes (bytes 4-9) to change
its value since i am able to control the sensors which the data were
based. i am just asking for your opinion if there is something wrong
with this program, otherwise, it could be a hardware problem.

thanks in advance.