I want to send standard output to the file "my_output.txt" but failed.

Here's the output:

inside value loop
------------------------------------------------------------
Server listening on UDP port 5001
Receiving 1470 byte datagrams
UDP buffer size:   108 KByte (default)
------------------------------------------------------------
[  3] local 192.168.16.2 port 5001 connected with 192.168.16.1 port 3189
[ ID] Interval       Transfer     Bandwidth       Jitter   Lost/Total Datagrams
[  3]  0.0- 5.0 sec  2.14 MBytes  3.61 Mbits/sec  0.369 ms    0/ 1528 (0%)
inside value loop3
clue1
clue2
inside value loop4
one iperf completed
***************************************

When I enable the local *STDOUT; in below code then I could see the above output on command prompt display (ofcourse server is sending some data):

my $file = 'my_output.txt';
use Win32::Process;
print"inside value loop\n";
# redirect stdout to a file
#local *STDOUT;
open STDOUT, '>', $file
  or die "can't redirect STDOUT to <$file> $!";
Win32::Process::Create(my $ProcessObj,
                        "D:\\IOT_AUTOMATION_UTILITY\\_SATURDAY_09-04-10\\adb_cmd.bat",
            "adb shell /data/app/iperf -u -s -p 5001",
                       0,
                       NORMAL_PRIORITY_CLASS,
                       ".") || die ErrorReport();
#$alarm_time = $IPERF_RUN_TIME+10; #20sec              

#$ProcessObj->Wait(40);
#print"inside value loop2\n";
#sleep $alarm_time;
sleep 40;


$ProcessObj->Kill(0);

sub ErrorReport{
    print Win32::FormatMessage( Win32::GetLastError() );
}