Data from flow graph is not updated

Hi, all
I met a problem when I tried to read data from USRP. I hope someone
can help me. Thanks.
Here is my flow graph:
source_c --> keep_one_in_n --> g.head --> gr.complex_to_mag -->
gr.vector_sink_f

if name == ‘main’:
tb = top_block()
try:
tb.start() # start executing flow graph in
another thread…
time.sleep(1)
main_loop(tb)
except KeyboardInterrupt:
pass

In main_loop function, I read data from vector_sink_f.
def main(tb):
while(True):
time.sleep(1)
data = tb.dst.data()

But when I print data, the result shows that data doesn’t change at all.
I don’t why. In my opinion, data should be updated as the flow graph
runs. And that changing data with time is what I wanted. Does anybody
know the reason? Thanks!
Ally

what do you mean updated? Where and when do you print the data?
If you print it after the block stops, the data will not change anyway.


Yang
Sent with Sparrow

I mean data should be different at different time. I print data after it
is assigned
def main(tb):
while(True):
time.sleep(1)
data = tb.dst.data()
print data

At 2011-05-22 23:14:11��Yang [email protected] wrote:

what do you mean updated? Where and when do you print the data?
If you print it after the block stops, the data will not change anyway.


Yang
Sent withSparrow

On 2011年5月22日星期日 at 下午10:13, lishan_wh wrote:

Hi, all
I met a problem when I tried to read data from USRP. I hope someone
can help me. Thanks.
Here is my flow graph:
source_c → keep_one_in_n → g.head → gr.complex_to_mag →
gr.vector_sink_f

if name == ‘main’:
tb = top_block()
try:
tb.start() # start executing flow graph in
another thread…
time.sleep(1)
main_loop(tb)
except KeyboardInterrupt:
pass

In main_loop function, I read data from vector_sink_f.
def main(tb):
while(True):
time.sleep(1)
data = tb.dst.data()

But when I print data, the result shows that data doesn’t change at all.
I don’t why. In my opinion, data should be updated as the flow graph
runs. And that changing data with time is what I wanted. Does anybody
know the reason? Thanks!
Ally