Hi there. I tried thousand ways the last weeks and I am desparing.
I need to write and read to /dev/ttyUSB0 where a infrared head is attached to read an electric meter.

The settings are 300 baud 7E1, no handshake
If I do this from shell in that way: 
1. cat /dev/ttyUSB0&amp
2. stty -F /dev/ttyUSB0 300 -parodd cs7 -cstopb parenb -ixoff -crtscts
+ -hupcl -ixon -opost -onlcr -isig -icanon -iexten -echo -echoe -echoc
+tl -echoke
3. echo -n -e '\x2F\x3F\x21\x0D\x0A' > /dev/ttyUSB0
4. echo -n -e '\x06\x30\x30\x30\x0D\x0A' > /dev/ttyUSB0

[download]
I get an answer as expected:

/LOG4LK13BD202015
C.1.0(06091772)
0.0.0(001LOG0006091772)
F.F(0000)
1.8.0(021183.342*kWh)
C.7.1(00000000)
C.7.2(00000001)
C.7.3(00000002)
0.2.1(ver.02, 150228, 671A)
C.2.1(1510121019)
C.2.9(1510121019)

[download]

Now I try to realize in perl to catch this output but all ways I have gone, nothing comes back to perl.
Only using Device::SerialPort I receive the first line "/LOG4LK13BD202015" but not more.

One of many examples: 

open( com, "+<","/dev/ttyUSB0" ) || die "Cannot open serial port : 
+$!\n";
my $raw = "\x2F\x3F\x21\x0D\x0A";
print com $raw;
my $raw = "\x06\x30\x30\x30\x0D\x0A";
print com $raw;

while( 1 )
{
    my $in = <com&gt;; 
    print "$in\n";
}

[download]
gives me:
/?!
000
/LOG4LK13BD202015

[download]
Finish!

I tried system calls in different way, different ways to open an file handle on the device, some perl modules - nothing worked for me.
Has anyone an idea or realized something like that in the past and can give me some help?

2019-05-28 Athanasius added code tags

In reply to r/w attached infrared head on /dev/ttyUSB0 by stoerti

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