Hi Monks,
I try to communicate with a serial device which should return 17 bytes if I send the command 0x11 0x00.
But this works only if I put a sleep between the write and read command.
Without sleep the read function return zero bytes. I also tried lookfor instead of read, but this did also not work.
How can I block during read/lookfor until I received all bytes? 
#!/usr/local/bin/perl -w

use Device::SerialPort;
use strict;

$|=1;

my %ergoCommands;

## initialize serial port
my $portname="/dev/ttyS0";
my $port = new Device::SerialPort ($portname);

$port->user_msg("ON");
$port->databits(8);
$port->baudrate(4800);
$port->parity("none");
$port->stopbits(1);
$port->handshake("xoff");

$port->write_settings() || undef $port;

my $count_out = $port->write("\x40\x0");
warn "command failed:$_[0]\n" unless ($count_out eq length($cmddata));
    
## I don't want to go asleep :(
##sleep(1);

## hmm.. does not block 
($real_in, $data_in) = $port->read(17);

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MP

In reply to read does not block by Monky Python

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