Data acquisition

[spintronic]

Dear friends,

I have a trouble with understanding the following. I have a very short
script (shown below) which works fine if I "run" step by step (or line
by line) in Python shell (type the first line/command -> press Enter,
etc.). I can get all numbers (actually, there are no numbers but a
long string, but this is not a problem) I need from a device:

'0.3345098119,0.01069121274,0.02111624694,0.03833379529,0.02462816409,0.0774275008,0.06554297421,0.07366750919,0.08122602002,0.004018369318,0.03508462415,0.04829900696,0.06383554085, ...'

However, when I start very the same list of commands as a script, it
gives me the following, which is certainly wrong:

[0.0, 0.0, 0.0, 0.0, 0.0,...]

Any ideas? Why there is a difference when I run the script or do it
command by command?

===========================
from visa import *

mw = instrument("GPIB0::20::INSTR", timeout = None)

mw.write("*RST")
mw.write("CALC1:DATA? FDATA")

a=mw.read()

print a
===========================
(That is really all!)


PS In this case I use Python Enthought for Windows, but I am not an
expert in Windows (I work usually in Linux but now I need to run this
data acquisition under Windows).